140 results on '"Robert G. Palgrave"'
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2. Challenges in High-Throughput Inorganic Materials Prediction and Autonomous Synthesis
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Josh Leeman, Yuhan Liu, Joseph Stiles, Scott B. Lee, Prajna Bhatt, Leslie M. Schoop, and Robert G. Palgrave
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Production of electric energy or power. Powerplants. Central stations ,TK1001-1841 ,Renewable energy sources ,TJ807-830 - Abstract
Materials discovery lays the foundation for many technological advancements. The prediction and discovery of new materials are not simple tasks. Here, we outline some basic principles of solid-state chemistry, which might help to advance both, and discuss pitfalls and challenges in materials discovery. Using the recent work of Szymanski et al. [Nature 624, 86 (2023)], which reported the autonomous discovery of 43 novel materials, as an example, we discuss problems that can arise in unsupervised materials discovery and hope that by addressing these, autonomous materials discovery can be brought closer to reality. We discuss all 43 synthetic products and point out four common shortfalls in the analysis. These errors unfortunately lead to the conclusion that no new materials have been discovered in that work. We conclude that there are two important points of improvement that require future work from the community, as follows. (i) Automated Rietveld analysis of powder x-ray diffraction data is not yet reliable. Future improvement of such, and the development of a reliable artificial-intelligence-based tool for Rietveld fitting, would be very helpful, not only for autonomous materials discovery but also for the community in general. (ii) We find that disorder in materials is often neglected in predictions. The predicted compounds investigated herein have all their elemental components located on distinct crystallographic positions but in reality, elements can share crystallographic sites, resulting in higher-symmetry space groups and—very often—known alloys or solid solutions. This error might be related to the difficulty of modeling disorder in a computationally economical way and needs to be addressed both by computational and experimental material scientists. We find that two thirds of the claimed successful materials in Szymanski et al. are likely to be known compositionally disordered versions of the predicted ordered compounds. We highlight important issues in materials discovery, computational chemistry, and autonomous interpretation of x-ray diffraction. We discuss concepts of materials discovery from an experimentalist point of view, which we hope will be helpful for the community to further advance this important new aspect of our field.
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- 2024
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3. Reply to 'Inconsistencies in the specific nucleobase pairing motif prone to photodimerization in a MOF nanoreactor'
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Samantha L. Anderson, Peter G. Boyd, Andrzej Gładysiak, Tu N. Nguyen, Robert G. Palgrave, Dominik Kubicki, Lyndon Emsley, Darren Bradshaw, Matthew J. Rosseinsky, Berend Smit, and Kyriakos C. Stylianou
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Science - Published
- 2022
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4. Nucleobase pairing and photodimerization in a biologically derived metal-organic framework nanoreactor
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Samantha L. Anderson, Peter G. Boyd, Andrzej Gładysiak, Tu N. Nguyen, Robert G. Palgrave, Dominik Kubicki, Lyndon Emsley, Darren Bradshaw, Matthew J. Rosseinsky, Berend Smit, and Kyriakos C. Stylianou
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Science - Abstract
Metal-organic frameworks have shown promise as nanoreactors, facilitating the synthesis of molecules that are otherwise difficult to isolate. Here, the authors design a framework featuring unobstructed adenine linkers to which thymine molecules can base-pair, allowing for thymine dimerization in the pores upon UV irradiation.
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- 2019
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5. Optimized Atmospheric-Pressure Chemical Vapor Deposition Thermochromic VO2 Thin Films for Intelligent Window Applications
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Delphine Malarde, Michael J. Powell, Raul Quesada-Cabrera, Rachel L. Wilson, Claire J. Carmalt, Gopinathan Sankar, Ivan P. Parkin, and Robert G. Palgrave
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Chemistry ,QD1-999 - Published
- 2017
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6. Accelerated optimization of transparent, amorphous zinc-tin-oxide thin films for optoelectronic applications
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Matthew J. Wahila, Zachary W. Lebens-Higgins, Keith T. Butler, Daniel Fritsch, Robert E. Treharne, Robert G. Palgrave, Joseph C. Woicik, Benjamin J. Morgan, Aron Walsh, and Louis F. J. Piper
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Biotechnology ,TP248.13-248.65 ,Physics ,QC1-999 - Abstract
In the last decade, transparent amorphous oxide semiconductors (TAOS) have become an essential component of many electronics, from ultra high resolution displays to solar cells. However, these disordered oxides typically rely on expensive component metals like indium to provide sufficient charge carrier conduction, and their optoelectronic properties are not as predictable and well-described as those of traditional, crystalline semiconductors. Herein we report on our comprehensive study of the amorphous zinc-tin-oxide (a-ZTO) system for use as an indium-free, n-type TAOS. Using a combination of high-throughput co-deposition growth, high resolution spectral mapping, and atomistic calculations, we explain the development of disorder-related subgap states in SnO2-like a-ZTO and optical bandgap reduction in ZnO-like a-ZTO. In addition, we report on a composition-induced electronic and structural transition in ZnO-like a-ZTO resulting in an exceptionally high figure of merit, comparable to that of amorphous indium-gallium-zinc-oxide. Our results accelerate the development of a-ZTO and similar systems as indium-free TAOS materials.
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- 2019
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7. Mixed valence Sn doped (CH3NH3)3Bi2Br9 produced by mechanochemical synthesis
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Xiaohan Jia, Yuhan Liu, Prajna Bhatt, Robin S. Perry, Ivan P. Parkin, and Robert G. Palgrave
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General Physics and Astronomy ,Physical and Theoretical Chemistry - Abstract
Mechanochemical synthesis leads to mixed valence Sn(ii)/Sn(iv) doping of the triple vacancy ordered perovskite MA3Bi2Br9.
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- 2023
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8. Computational Prediction and Experimental Realization of Earth-Abundant Transparent Conducting Oxide Ga-Doped ZnSb2O6
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Adam J. Jackson, Benjamin J. Parrett, Joe Willis, Alex M. Ganose, W. W. Winnie Leung, Yuhan Liu, Benjamin A. D. Williamson, Timur K. Kim, Moritz Hoesch, Larissa S. I. Veiga, Raman Kalra, Jens Neu, Charles A. Schmuttenmaer, Tien-Lin Lee, Anna Regoutz, Tung-Chun Lee, Tim D. Veal, Robert G. Palgrave, Robin Perry, and David O. Scanlon
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Fuel Technology ,Renewable Energy, Sustainability and the Environment ,Chemistry (miscellaneous) ,Materials Chemistry ,Energy Engineering and Power Technology - Abstract
Transparent conducting oxides have become ubiquitous in modern optoelectronics. However, the number of oxides that are transparent to visible light and have the metallic-like conductivity necessary for applications is limited to a handful of systems that have been known for the past 40 years. In this work, we use hybrid density functional theory and defect chemistry analysis to demonstrate that tri-rutile zinc antimonate, ZnSb2O6, is an ideal transparent conducting oxide and to identify gallium as the optimal dopant to yield high conductivity and transparency. To validate our computational predictions, we have synthesized both powder samples and single crystals of Ga-doped ZnSb2O6 which conclusively show behavior consistent with a degenerate transparent conducting oxide. This study demonstrates the possibility of a family of Sb(V)-containing oxides for transparent conducting oxide and power electronics applications.
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- 2022
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9. Phase transitions and optical properties of the trigonal perovskite (CH3NH3)2TeCl6
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Yuhan Liu, Jeremy K. Cockcroft, Zizhen Chen, Michael A. Hayward, Paul F. Henry, Robin S. Perry, and Robert G. Palgrave
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Materials Chemistry ,Materialkemi ,General Chemistry - Abstract
Vacancy-ordered double perovskites A2BX6are attracting attention due to the isolated octahedra making them an ideal playground for studying perovskite structure-property relationships. MA2TeCl6single crystals have been successfully grown from solution. X-ray structure experiments as a function of temperature have demonstrated two structural phase transitions: from cubicFm3̄m(high temperature, phase I) to trigonalP3̄m1 (intermediate temperature, phase II) at 460 K and then to trigonalP3̄1c(low temperature, phase III) at 200 K. Intriguingly, we observe a negative thermal expansion for thec-axis in phase II believed to caused by dynamic tilting of the C–N bond in the MA+ion. We have modified and extended the calculation of the Brown radii ratio in the perovskites to include hybrid A2BX6compounds by selecting the shortest A–X distance for the ratio equation. We find that for ratios between 0.89 and 1.17, typically theFm3̄mcubic structure is observed, while for ratios above 1.17, mostly distorted structures are found.
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- 2023
10. Physico‐Chemical Properties of Magnetic Dicationic Ionic Liquids with Tetrahaloferrate Anions
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Anham Zafar, null Imtiaz‐ud‐Din, Robert G. Palgrave, Haji Muhammad, Sammer Yousuf, and Tim Evans
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General Chemistry - Abstract
A series of imidazolium-based symmetrical and asymmetrical dicationic ionic liquids (DcILs) with alkyl spacers of different length and with [FeCl
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- 2023
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11. 2023 roadmap for potassium-ion batteries
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Yang Xu, Magda Titirici, Jingwei Chen, Furio Cora, Patrick L Cullen, Jacqueline Sophie Edge, Kun Fan, Ling Fan, Jingyu Feng, Tomooki Hosaka, Junyang Hu, Weiwei Huang, Timothy I Hyde, Sumair Imtiaz, Feiyu Kang, Tadhg Kennedy, Eun Jeong Kim, Shinichi Komaba, Laura Lander, Phuong Nam Le Pham, Pengcheng Liu, Bingan Lu, Fanlu Meng, David Mitlin, Laure Monconduit, Robert G Palgrave, Lei Qin, Kevin M Ryan, Gopinathan Sankar, David O Scanlon, Tianyi Shi, Lorenzo Stievano, Henry R Tinker, Chengliang Wang, Hang Wang, Huanlei Wang, Yiying Wu, Dengyun Zhai, Qichun Zhang, Min Zhou, Jincheng Zou, Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM), Université de Montpellier (UM), Advanced Lithium Energy Storage Systems - ALISTORE-ERI (ALISTORE-ERI), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Chalmers University of Technology [Göteborg], Réseau sur le stockage électrochimique de l'énergie (RS2E), Aix Marseille Université (AMU)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Collège de France (CdF (institution))-Université de Picardie Jules Verne (UPJV)-Ecole Nationale Supérieure de Chimie de Paris - Chimie ParisTech-PSL (ENSCP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Pau et des Pays de l'Adour (UPPA)-Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Université Grenoble Alpes (UGA)-Nantes Université (Nantes Univ)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM), and ANR-10-LABX-0076,STORE-EX,Laboratory of excellency for electrochemical energy storage(2010)
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General Energy ,Materials Science (miscellaneous) ,Materials Chemistry ,[CHIM]Chemical Sciences ,[CHIM.MATE]Chemical Sciences/Material chemistry - Abstract
The heavy reliance of lithium-ion batteries (LIBs) has caused rising concerns on the sustainability of lithium and transition metal and the ethic issue around mining practice. Developing alternative energy storage technologies beyond lithium has become a prominent slice of global energy research portfolio. The alternative technologies play a vital role in shaping the future landscape of energy storage, from electrified mobility to the efficient utilization of renewable energies and further to large-scale stationary energy storage. Potassium-ion batteries (PIBs) are a promising alternative given its chemical and economic benefits, making a strong competitor to LIBs and sodium-ion batteries for different applications. However, many are unknown regarding potassium storage processes in materials and how it differs from lithium and sodium and understanding of solid–liquid interfacial chemistry is massively insufficient in PIBs. Therefore, there remain outstanding issues to advance the commercial prospects of the PIB technology. This Roadmap highlights the up-to-date scientific and technological advances and the insights into solving challenging issues to accelerate the development of PIBs. We hope this Roadmap aids the wider PIB research community and provides a cross-referencing to other beyond lithium energy storage technologies in the fast-pacing research landscape.
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- 2023
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12. Electro‐Oxidation of Titanium Carbide Nanoparticles in Aqueous Acid Creates TiC@TiO 2 Core‐Shell Structures
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Pranati Nayak, Richard G. Compton, Robert G. Palgrave, and Ruo-Chen Xie
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Materials science ,Aqueous solution ,Titanium carbide ,Shell (structure) ,Nanoparticle ,Electrolyte ,Electrochemistry ,Catalysis ,chemistry.chemical_compound ,Chemical engineering ,chemistry ,Titanium dioxide ,Cyclic voltammetry - Abstract
Titanium carbide (TiC) is an attractive support material used in electro-catalysis and sensing. We report the electrochemistry of TiC nanoparticles (NPs, 35–50 nm in diameter) in different electrolytes in the pH range of 0 to 8. The TiC NPs undergo irreversible oxidation in acidic, basic, and neutral media, attributed to the partial conversion into titanium dioxide (TiO2) with the amount of oxidation highly dependent on the pH of the solution. In H2SO4 (pH 0), multiple voltammetric scans revealed the conversion to be partial but repeated scans allowed a conversion approaching 100% to be obtained with 20 scans generating a ca 60% level of oxidation. The process is inferred to lead to the formation of TiC@TiO2 core-shell nanoparticles (~12.5 nm core radius and ~5 nm shell width for a 60% conversion) and this value sharply decreases with an increase of pH. Independent measurements were conducted at a single NP level (via nano-impact experiments) to confirm the oxidation of the NPs, showing consistent agreement with the bulk measurements.
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- 2021
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13. Advanced XPS characterization: XPS-based multi-technique analyses for comprehensive understanding of functional materials
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Roxy Lee, Robert G. Palgrave, Mark A. Isaacs, Philip Rosser Davies, Josh A. Davies-Jones, Shaoliang Guan, and David J. Morgan
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Materials science ,Electron energy ,X-ray photoelectron spectroscopy ,Analytical technique ,Materials Chemistry ,General Materials Science ,Nanotechnology ,Characterization (materials science) - Abstract
X-ray photoelectron spectroscopy (XPS) has achieved maturity as an analytical technique in that it is a ubiquitous tool in the materials community, however as made apparent by recent reviews highlighting it's misuse as a means of chemical deduction, it is a practice which is greatly misunderstood even in its simplest form. Advanced XPS techniques, or a combination of XPS and a complementary surficial probe may elicit auxiliary information outside of the scope of the standard sphere of appreciation. This review aims to bring to the attention of the general materials audience a landscape of some atypical applications of lab-based XPS and combinatorial approaches of related surface analysis, such as ion scattering, ultraviolet photoelectron, electron energy loss and auger emission spectroscopies found on many lab-based instrument set-ups.
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- 2021
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14. Geometric Analysis and Formability of the Cubic A2BX6 Vacancy-Ordered Double Perovskite Structure
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Robert G. Palgrave, Warda Rahim, Chenyang Lyu, Anjie Cheng, Tianyi Shi, Ziheng Wang, and David O. Scanlon
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Materials science ,Geometric analysis ,Condensed matter physics ,General Chemical Engineering ,Structure (category theory) ,02 engineering and technology ,General Chemistry ,Radius ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Ion ,chemistry.chemical_compound ,Metal halides ,chemistry ,Vacancy defect ,Materials Chemistry ,Formability ,SPHERES ,0210 nano-technology - Abstract
A geometric analysis of the cubic A2BX6 structure commonly formed by metal halides is presented. Using the “hard-sphere” approximation, where the ions are represented by spheres of a fixed radius, ...
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- 2020
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15. LaSrCo0.5Rh0.5O3.25 and LaSrNi0.5Rh0.5O3.25:Topochemically Reduced, Mixed Valence Rh(I)/Rh(III) Oxides
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Michael A. Hayward, Zheying Xu, and Robert G. Palgrave
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Inorganic Chemistry ,Magnetization ,Crystallography ,Valence (chemistry) ,X-ray photoelectron spectroscopy ,chemistry ,Oxidation state ,chemistry.chemical_element ,Disproportionation ,Physical and Theoretical Chemistry ,Rhodium - Abstract
Topochemical reduction of the n = 1 Ruddlesden-Popper phases LaSrCo0.5Rh0.5O4 and LaSrNi0.5Rh0.5O4 with Zr yields LaSrCo0.5Rh0.5O3.25 and LaSrNi0.5Rh0.5O3.25, respectively. Magnetization and XPS data reveal that while the rhodium centers in LaSrCo0.5Rh0.5O3.25 and LaSrNi0.5Rh0.5O3.25 have an average oxidation state of Rh2+, these are actually mixed valence Rh(I,III) compounds, with the disproportionation of Rh2+ driven by the favorability of locating d8 Rh1+ and d6 Rh3+ cations within square-planar and square-based pyramidal coordination sites, respectively.
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- 2020
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16. Demonstration of Visible Light-Activated Photocatalytic Self-Cleaning by Thin Films of Perovskite Tantalum and Niobium Oxynitrides
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Robert G. Palgrave, Antonio Iborra-Torres, Geoffrey Hyett, and Alexander N. Kulak
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Materials science ,010405 organic chemistry ,Tantalum ,Oxide ,chemistry.chemical_element ,Chemical vapor deposition ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Photocatalysis ,General Materials Science ,Thin film ,Cobalt oxide ,Perovskite (structure) ,Visible spectrum - Abstract
Metal oxynitrides adopting the perovskite structure have been shown to be visible light-activated photocatalysts, and therefore, they have potential as self-cleaning materials where surface organic pollutants can be removed by photomineralization. In this work, we establish a route for the deposition of thin films for seven perovskite oxynitrides, CaTaO2N, SrTaO2N, BaTaO2N, LaTaON2, EuTaO2N, SrNbO2N, and LaNbON2, on quartz and alumina substrates using dip-coating of a polymer gel to form an amorphous oxide precursor film, followed by ammonolysis. The initially deposited oxide films were annealed at 800 °C, followed by ammonolysis at temperatures from 850 to 1000 °C. The perovskite oxynitride thin films were characterized using XRD and EDX, with band gaps determined using Tauc plots derived from UV-vis spectroscopic data. A cobalt oxide co-catalyst was deposited onto each film by drop casting, and the photocatalytic activity assessed under visible light using dichloroindophenol dye degradation in the presence of a sacrificial oxidant. The light source used was a solar simulator equipped with a 400 nm cut-off filter. The dye degradation test demonstrated photocatalytic activity in all samples except EuTaO2N and BaTaO2N. The three most active samples were SrNbO2N, CaTaO2N, and SrTaO2N. The cobalt oxide loading was optimized for these three films and found to be 0.3 μg cm-2. Further, catalytic tests were conducted using stearic acid degradation, and this found the film of SrNbO2N with the cobalt oxide co-catalyst to be the most active for complete mineralization of this model pollutant.
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- 2020
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17. Structure and magnetism of the Rh4+-containing perovskite oxides La0.5Sr0.5Mn0.5Rh0.5O3and La0.5Sr0.5Fe0.5Rh0.5O3
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Robert G. Palgrave, Nijat Hasanli, Michael A. Hayward, Alex Scrimshire, and Paul A. Bingham
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Materials science ,Magnetism ,media_common.quotation_subject ,Frustration ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Inorganic Chemistry ,Magnetization ,Crystallography ,Transition metal ,Ferromagnetism ,Oxidation state ,0210 nano-technology ,Powder diffraction ,media_common ,Perovskite (structure) - Abstract
Synchrotron X-ray powder diffraction data indicate that La0.5Sr0.5Mn0.5Rh0.5O3and La0.5Sr0.5Fe0.5Rh0.5O3adopt distorted perovskite structures (space groupPnma) withA-site andB-site cation disorder. A combination of XPS and57Fe Mössbauer data indicate the transition metal cations in the two phases adopt Mn3+/Rh4+and Fe3+/Rh4+oxidation state combinations respectively. Transport data indicate both phases are insulating, withρ vs.Tdependences consistent with 3D variable-range hopping. Magnetisation data reveal that La0.5Sr0.5Mn0.5Rh0.5O3adopts a ferromagnetic state belowTc∼ 60 K, which is rationalized on the basis of couplingviaa dynamic Jahn–Teller distortion mechanism. In contrast, magnetic data reveal La0.5Sr0.5Fe0.5Rh0.5O3undergoes a transition to a spin-glass state atT∼ 45 K, attributed to frustration between nearest-neighbour Fe–Rh and next-nearest-neighbour Fe–Fe couplings.
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- 2020
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18. Patterning of metal oxide thin films using a H2/He atmospheric pressure plasma jet
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Robert G. Palgrave, Raul Quesada Cabrera, Daren J. Caruana, Sanjayan Sathasivam, and M. Emre Sener
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Auger electron spectroscopy ,Materials science ,Oxide ,Analytical chemistry ,chemistry.chemical_element ,Atmospheric-pressure plasma ,02 engineering and technology ,equipment and supplies ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Tin oxide ,01 natural sciences ,Pollution ,Copper ,0104 chemical sciences ,Titanium oxide ,chemistry.chemical_compound ,symbols.namesake ,X-ray photoelectron spectroscopy ,chemistry ,symbols ,Environmental Chemistry ,0210 nano-technology ,Raman spectroscopy - Abstract
A hydrogen-doped helium atmospheric pressure plasma jet (APPJ) is shown to be effective for the chemical reduction of metal oxides. Copper and tin oxide films (CuO and SnO2) show rapid (
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- 2020
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19. Mixed valence Sn doped (CH3NH3)3Bi2Br9 produced by mechanochemical synthesis
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R. S. Perry, Ivan P. Parkin, Robert G. Palgrave, Xiaohan Jia, and Yuhan Liu
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chemistry.chemical_classification ,Crystallinity ,Valence (chemistry) ,Materials science ,X-ray photoelectron spectroscopy ,chemistry ,Doping ,Iodide ,Halide ,Physical chemistry ,chemistry.chemical_element ,Luminescence ,Bismuth - Abstract
Bismuth halides with formula A3Bi2X9, where A is an inorganic or organic cation, show desirable properties as solar absorbers and luminescent materials. Control of structural and electronic dimensionality of these compounds is important to yield materials with good light absorption and charge transport. Here we report mechanochemical reaction of (CH3NH3)3Bi2Br9 with SnBr2 at room temperature in air, yielding a material with strong absorption across the visible and near-infrared (NIR) region. We attribute this to mixed valence doping of Sn(II) and Sn(IV) on the Bi site. X-ray diffraction shows no secondary phases, even after heating at 200oC to improve crystallinity. X-ray photoelectron spectroscopy suggests the presence of Sn(II) and Sn(IV) states. A similar approach to dope Sn into the iodide analogue (CH3NH3)3Bi2I9 was unsuccessful.
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- 2021
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20. Enhanced visible light absorption in layered Cs3Bi2Br9 through mixed-valence Sn(ii)/Sn(iv) doping
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Lina Zhang, Seán R. Kavanagh, Samuel D. Stranks, Robert G. Palgrave, Clare P. Grey, Dominik J. Kubicki, David O. Scanlon, Krishanu Dey, Krzysztof Galkowski, Aron Walsh, Chantalle J Krajewska, Grey, Clare [0000-0001-5572-192X], Stranks, Samuel [0000-0002-8303-7292], and Apollo - University of Cambridge Repository
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Materials science ,INITIO MOLECULAR-DYNAMICS ,Band gap ,Chemistry, Multidisciplinary ,CS3SB2I9 ,BAND-GAP ,02 engineering and technology ,Intervalence charge transfer ,010402 general chemistry ,01 natural sciences ,7. Clean energy ,ENERGY ,CHARGE-TRANSFER ,X-ray photoelectron spectroscopy ,Perovskite (structure) ,3403 Macromolecular and Materials Chemistry ,Science & Technology ,Valence (chemistry) ,34 Chemical Sciences ,Doping ,OPTICAL-PROPERTIES ,General Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,3. Good health ,3402 Inorganic Chemistry ,Chemistry ,Crystallography ,PEROVSKITES ,Physical Sciences ,LUMINESCENCE ,PHASE-TRANSITION ,3406 Physical Chemistry ,PHOTOLUMINESCENCE ,Density functional theory ,03 Chemical Sciences ,0210 nano-technology ,Visible spectrum - Abstract
Lead-free halides with perovskite-related structures, such as the vacancy-ordered perovskite Cs3Bi2Br9, are of interest for photovoltaic and optoelectronic applications. We find that addition of SnBr2 to the solution-phase synthesis of Cs3Bi2Br9 leads to substitution of up to 7% of the Bi(III) ions by equal quantities of Sn(II) and Sn(IV). The nature of the substitutional defects was studied by X-ray diffraction, 133Cs and 119Sn solid state NMR, X-ray photoelectron spectroscopy and density functional theory calculations. The resulting mixed-valence compounds show intense visible and near infrared absorption due to intervalence charge transfer, as well as electronic transitions to and from localised Sn-based states within the band gap. Sn(II) and Sn(IV) defects preferentially occupy neighbouring B-cation sites, forming a double-substitution complex. Unusually for a Sn(II) compound, the material shows minimal changes in optical and structural properties after 12 months storage in air. Our calculations suggest the stabilisation of Sn(II) within the double substitution complex contributes to this unusual stability. These results expand upon research on inorganic mixed-valent halides to a new, layered structure, and offer insights into the tuning, doping mechanisms, and structure–property relationships of lead-free vacancy-ordered perovskite structures.
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- 2021
21. Experimental measurement and prediction of ionic liquid ionisation energies
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Alexander Large, Kevin R. J. Lovelock, Richard M. Fogarty, Coby J. Clarke, Pilar Ferrer, Roger A. Bennett, Ekaterina Gousseva, Peter Licence, David A. Duncan, Jake M. Seymour, Robert G. Palgrave, and Federica Venturini
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Valence (chemistry) ,Materials science ,General Physics and Astronomy ,Electronic structure ,Electrochemistry ,Ion ,chemistry.chemical_compound ,X-ray photoelectron spectroscopy ,chemistry ,Chemical physics ,Ionic liquid ,Ionization energy ,Physical and Theoretical Chemistry ,HOMO/LUMO - Abstract
Ionic liquid (IL) valence electronic structure provides key descriptors for understanding and predicting IL properties. The ionisation energies of 60 ILs are measured and the most readily ionised valence state of each IL (the highest occupied molecular orbital, HOMO) is identified using a combination of X-ray photoelectron spectroscopy (XPS) and synchrotron resonant XPS. A structurally diverse range of cations and anions were studied. The cation gave rise to the HOMO for nine of the 60 ILs presented here, meaning it is energetically more favourable to remove an electron from the cation than the anion. The influence of the cation on the anion electronic structure (and vice versa) were established; the electrostatic effects are well understood and demonstrated to be consistently predictable. We used this knowledge to make predictions of both ionisation energy and HOMO identity for a further 516 ILs, providing a very valuable dataset for benchmarking electronic structure calculations and enabling the development of models linking experimental valence electronic structure descriptors to other IL properties, e.g. electrochemical stability. Furthermore, we provide design rules for the prediction of the electronic structure of ILs.
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- 2021
22. Enhanced visible light absorption in layered Cs3Bi2Br9 through mixed-valence Sn(II) / Sn(IV) doping
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Seán R. Kavanagh, David O. Scanlon, Robert G. Palgrave, Samuel D. Stranks, Aron Walsh, Clare P. Grey, Krishanu Dey, Chantalle J Krajewska, Dominik J. Kubicki, Lina Zhang, and Krzysztof Galkowski
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Crystallography ,Materials science ,Valence (chemistry) ,X-ray photoelectron spectroscopy ,Band gap ,Doping ,Density functional theory ,Intervalence charge transfer ,Visible spectrum ,Perovskite (structure) - Abstract
Lead-free halides with perovskite-related structures, such as the vacancy-ordered perovskite Cs3Bi2Br9, are of interest for photovoltaic and optoelectronic applications. We find that addition of SnBr2 to the solution-phase synthesis of Cs3Bi2Br9 leads to substitution of up to 7% of the Bi(III) ions by equal quantities of Sn(II) and Sn(IV). The nature of the substitutional defects was studied by X-ray diffraction, 133Cs and 119Sn solid state NMR, X-ray photoelectron spectroscopy and density functional theory calculations. The resulting mixed-valence compounds show intense visible and near infrared absorption due to intervalence charge transfer, as well as electronic transitions to and from localised Sn-based states within the band gap. Sn(II) and Sn(IV) defects preferentially occupy neighbouring B-cation sites, forming a double-substitution complex. Unusually for a Sn(II) compound, the material shows minimal changes in optical and structural properties after 12 months storage in air. Our calculations suggest the stabilisation of Sn(II) within the double substitution complex contributes to this unusual stability. These results expand upon research on inorganic mixed-valent halides to a new, layered structure, and offer insights into the tuning, doping mechanisms, and structure-property relationships of lead-free vacancy-ordered perovskite structures.
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- 2021
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23. Enhanced visible light absorption in layered Cs
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Chantalle J, Krajewska, Seán R, Kavanagh, Lina, Zhang, Dominik J, Kubicki, Krishanu, Dey, Krzysztof, Gałkowski, Clare P, Grey, Samuel D, Stranks, Aron, Walsh, David O, Scanlon, and Robert G, Palgrave
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Chemistry - Abstract
Lead-free halides with perovskite-related structures, such as the vacancy-ordered perovskite Cs3Bi2Br9, are of interest for photovoltaic and optoelectronic applications. We find that addition of SnBr2 to the solution-phase synthesis of Cs3Bi2Br9 leads to substitution of up to 7% of the Bi(iii) ions by equal quantities of Sn(ii) and Sn(iv). The nature of the substitutional defects was studied by X-ray diffraction, 133Cs and 119Sn solid state NMR, X-ray photoelectron spectroscopy and density functional theory calculations. The resulting mixed-valence compounds show intense visible and near infrared absorption due to intervalence charge transfer, as well as electronic transitions to and from localised Sn-based states within the band gap. Sn(ii) and Sn(iv) defects preferentially occupy neighbouring B-cation sites, forming a double-substitution complex. Unusually for a Sn(ii) compound, the material shows minimal changes in optical and structural properties after 12 months storage in air. Our calculations suggest the stabilisation of Sn(ii) within the double substitution complex contributes to this unusual stability. These results expand upon research on inorganic mixed-valent halides to a new, layered structure, and offer insights into the tuning, doping mechanisms, and structure–property relationships of lead-free vacancy-ordered perovskite structures., Mixed valence Sn doping of Cs3Bi2Br9 leads to broad visible light absorption.
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- 2021
24. An experimental and theoretical study into NaSbS2 as an emerging solar absorber
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W. W. Winnie Leung, David O. Scanlon, Robert G. Palgrave, and Christopher N. Savory
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Materials science ,Band gap ,business.industry ,Earth abundant ,02 engineering and technology ,General Chemistry ,Electronic structure ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Engineering physics ,0104 chemical sciences ,Renewable energy ,Photovoltaics ,Thermoelectric effect ,Materials Chemistry ,0210 nano-technology ,business ,Absorption (electromagnetic radiation) ,Solar absorber - Abstract
As photovoltaics have grown to become one of the dominant renewable energy generating technologies, attention has fallen upon thin-film materials as a route to lightweight, flexible and portable solar cells. NaSbS2 has recently been proposed as a non-toxic, earth abundant solar absorber for thin-film cells. In this study, we use a combined theoretical and experimental approach to characterize and assess the electronic and optical properties of NaSbS2 as an emerging solar absorber. Our results, utilising two theoretical efficiency metrics, demonstrate that NaSbS2 may be limited for use in single-junction cells by a forbidden band gap and slow absorption onset. Other features of its electronic structure, however, indicate that the material may still be promising in thermoelectric applications.
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- 2019
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25. Indium Gallium Oxide Alloys: Electronic Structure, Optical Gap, Surface Space Charge, and Chemical Trends within Common-Cation Semiconductors
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Joel B. Varley, Philip A. E. Murgatroyd, Michael Lorenz, Marius Grundmann, A. Hassa, Tim D. Veal, Robert G. Palgrave, Holger von Wenckstern, Jack E. N. Swallow, and Anna Regoutz
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010302 applied physics ,Surface (mathematics) ,Materials science ,business.industry ,Physics::Optics ,chemistry.chemical_element ,02 engineering and technology ,Electronic structure ,021001 nanoscience & nanotechnology ,01 natural sciences ,Space charge ,Semiconductor ,Gallium oxide ,X-ray photoelectron spectroscopy ,chemistry ,0103 physical sciences ,Optoelectronics ,General Materials Science ,0210 nano-technology ,business ,Indium ,Transparent conducting film - Abstract
The electronic and optical properties of (InxGa1–x)2O3 alloys are highly tunable, giving rise to a myriad of applications including transparent conductors, transparent electronics, and solar-blind ...
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- 2021
26. 2021 roadmap for sodium-ion batteries
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John T. S. Irvine, Emma Kendrick, Valerie R. Seymour, Aamod V. Desai, Edmund J. Cussen, Peter Gross, Andrew J. Naylor, Maria-Magdalena Titirici, Jake M. Brittain, Rebecca Boston, Ruth Sayers, Stewart A. M. Dickson, Sudeshna Sen, Sara I. R. Costa, Zhuangnan Li, Ashish Rudola, Heather Au, Dominic S. Wright, Nuria Tapia-Ruiz, Yongseok Choi, Hande Alptekin, John M. Griffin, Martin O. Jones, Marco Amores, Shahin Nikman, Eun Jeong Kim, A. Robert Armstrong, Reza Younesi, Maria Crespo Ribadeneyra, Laure Monconduit, William I. F. David, Christopher I Thomas, Patrik Johansson, Serena A. Cussen, Grant S. Stone, Jincheng Tong, Russell E. Morris, Clare P. Grey, Alexandre Ponrouch, Oleg Kolosov, Emmanuel I. Eweka, Darren M. C. Ould, Robert G. Palgrave, Thomas J. Wood, Yue Chen, Jerry Barker, Ronnie Mogensen, Stijn F. L. Mertens, Philippe Poizot, Juan Forero-Saboya, David O. Scanlon, Manish Chhowalla, Lorenzo Stievano, Emily M. Reynolds, Xiao Hua, Moulay Tahar Sougrati, William R. Brant, Martin Karlsmo, Stéven Renault, Christopher A. O’Keefe, Begoña Silván, Lancaster University, Harwell Science and Innovation Campus, Imperial College London, University of Sheffield [Sheffield], Faradion Limited, University of Virginia [Charlottesville], University of Oxford [Oxford], University of Cambridge [UK] (CAM), University College of London [London] (UCL), University of St Andrews [Scotland], AUTRES, Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Chalmers University of Technology [Gothenburg, Sweden], Science and Technology Facilities Council (STFC), University of Birmingham [Birmingham], Uppsala University, Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC), Réseau sur le stockage électrochimique de l'énergie (RS2E), Université de Picardie Jules Verne (UPJV)-Institut de Chimie du CNRS (INC)-Aix Marseille Université (AMU)-Université de Pau et des Pays de l'Adour (UPPA)-Université de Nantes (UN)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Ecole Nationale Supérieure de Chimie de Paris - Chimie ParisTech-PSL (ENSCP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Collège de France (CdF (institution))-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Université Grenoble Alpes (UGA)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM), Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN), Alistore, European Commission, Swedish Research Council, Swedish Energy Agency, Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning, Ministerio de Economía, Industria y Competitividad (España), Faraday Institution, Austrian Science Fund, Innovate UK, Tapia-Ruiz, Nuria [0000-0002-5005-7043], Armstrong, A Robert [0000-0003-1937-0936], Alptekin, Hande [0000-0001-6065-0513], Au, Heather [0000-0002-1652-2204], Barker, Jerry [0000-0002-8791-1119], Brant, William R [0000-0002-8658-8938], Choi, Yong-Seok [0000-0002-3737-2989], Costa, Sara I R [0000-0001-8105-207X], Crespo Ribadeneyra, Maria [0000-0001-6455-4430], Cussen, Serena A [0000-0002-9303-4220], Desai, Aamod V [0000-0001-7219-3428], Forero-Saboya, Juan D [0000-0002-3403-6066], Griffin, John M [0000-0002-8943-3835], Irvine, John T S [0000-0002-8394-3359], Johansson, Patrik [0000-0002-9907-117X], Karlsmo, Martin [0000-0002-0437-6860], Kendrick, Emma [0000-0002-4219-964X], Kolosov, Oleg V [0000-0003-3278-9643], Mertens, Stijn F L [0000-0002-5715-0486], Monconduit, Laure [0000-0003-3698-856X], Naylor, Andrew J [0000-0001-5641-7778], Poizot, Philippe [0000-0003-1865-4902], Renault, Stéven [0000-0002-6500-0015], Rudola, Ashish [0000-0001-9368-0698], Sayers, Ruth [0000-0003-1289-0998], Seymour, Valerie R [0000-0003-3333-5512], Silván, Begoña [0000-0002-1273-3098], Sougrati, Moulay Tahar [0000-0003-3740-2807], Stievano, Lorenzo [0000-0001-8548-0231], Thomas, Chris I [0000-0001-8090-4541], Titirici, Maria-Magdalena [0000-0003-0773-2100], Tong, Jincheng [0000-0001-7762-1460], Wood, Thomas J [0000-0002-5893-5664], Younesi, Reza [0000-0003-2538-8104], Apollo - University of Cambridge Repository, Kim, Eunjeong [0000-0002-2941-068], Kim, Eunjeong [0000-0002-2941-0682], University of Virginia, University of Oxford, Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM), Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Aix Marseille Université (AMU)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Collège de France (CdF (institution))-Université de Picardie Jules Verne (UPJV)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Ecole Nationale Supérieure de Chimie de Paris - Chimie ParisTech-PSL (ENSCP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Pau et des Pays de l'Adour (UPPA)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Université Grenoble Alpes (UGA), Université de Nantes (UN)-Université de Nantes (UN)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Tapia-Ruiz, N [0000-0002-5005-7043], Armstrong, AR [0000-0003-1937-0936], Alptekin, H [0000-0001-6065-0513], Au, H [0000-0002-1652-2204], Barker, J [0000-0002-8791-1119], Brant, WR [0000-0002-8658-8938], Choi, YS [0000-0002-3737-2989], Costa, SIR [0000-0001-8105-207X], Ribadeneyra, MC [0000-0001-6455-4430], Cussen, SA [0000-0002-9303-4220], Desai, AV [0000-0001-7219-3428], Forero-Saboya, JD [0000-0002-3403-6066], Griffin, JM [0000-0002-8943-3835], Irvine, JTS [0000-0002-8394-3359], Johansson, P [0000-0002-9907-117X], Karlsmo, M [0000-0002-0437-6860], Kendrick, E [0000-0002-4219-964X], Kolosov, OV [0000-0003-3278-9643], Mertens, SFL [0000-0002-5715-0486], Monconduit, L [0000-0003-3698-856X], Naylor, AJ [0000-0001-5641-7778], Poizot, P [0000-0003-1865-4902], Renault, S [0000-0002-6500-0015], Rudola, A [0000-0001-9368-0698], Sayers, R [0000-0003-1289-0998], Seymour, VR [0000-0003-3333-5512], Silván, B [0000-0002-1273-3098], Sougrati, MT [0000-0003-3740-2807], Stievano, L [0000-0001-8548-0231], Thomas, CI [0000-0001-8090-4541], Titirici, MM [0000-0003-0773-2100], Tong, J [0000-0001-7762-1460], Wood, TJ [0000-0002-5893-5664], Younesi, R [0000-0003-2538-8104], The Faraday Institution, University of St Andrews. School of Chemistry, University of St Andrews. Centre for Energy Ethics, University of St Andrews. Centre for Designer Quantum Materials, and University of St Andrews. EaSTCHEM
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Chemical process ,Technology ,Computer science ,PAIR DISTRIBUTION FUNCTION ,HIGH-ENERGY DENSITY ,ELECTROCHEMICAL PROPERTIES ,Materialkemi ,02 engineering and technology ,01 natural sciences ,7. Clean energy ,Materials Chemistry ,QD ,LITHIUM-ION ,Energy demand ,Scope (project management) ,anodes ,NA2TI3O7 NANOSHEETS ,[CHIM.MATE]Chemical Sciences/Material chemistry ,sodium ion ,021001 nanoscience & nanotechnology ,Variety (cybernetics) ,General Energy ,Roadmap ,T-DAS ,Lithium ,0210 nano-technology ,Battery (electricity) ,energy materials ,Energy & Fuels ,HIGH-CAPACITY ANODE ,batteries ,Materials Science (miscellaneous) ,Materials Science ,chemistry.chemical_element ,Materials Science, Multidisciplinary ,electrolytes ,010402 general chemistry ,Energy storage ,MECHANISTIC INSIGHTS ,SDG 7 - Affordable and Clean Energy ,STRUCTURAL EVOLUTION ,SOLID-ELECTROLYTE INTERPHASE ,Science & Technology ,QD Chemistry ,0104 chemical sciences ,chemistry ,13. Climate action ,Sustainability ,HIGH-PERFORMANCE CATHODE ,Biochemical engineering ,cathodes - Abstract
Tapia-Ruiz, Nuria et al., Increasing concerns regarding the sustainability of lithium sources, due to their limited availability and consequent expected price increase, have raised awareness of the importance of developing alternative energy-storage candidates that can sustain the ever-growing energy demand. Furthermore, limitations on the availability of the transition metals used in the manufacturing of cathode materials, together with questionable mining practices, are driving development towards more sustainable elements. Given the uniformly high abundance and cost-effectiveness of sodium, as well as its very suitable redox potential (close to that of lithium), sodium-ion battery technology offers tremendous potential to be a counterpart to lithium-ion batteries (LIBs) in different application scenarios, such as stationary energy storage and low-cost vehicles. This potential is reflected by the major investments that are being made by industry in a wide variety of markets and in diverse material combinations. Despite the associated advantages of being a drop-in replacement for LIBs, there are remarkable differences in the physicochemical properties between sodium and lithium that give rise to different behaviours, for example, different coordination preferences in compounds, desolvation energies, or solubility of the solid–electrolyte interphase inorganic salt components. This demands a more detailed study of the underlying physical and chemical processes occurring in sodium-ion batteries and allows great scope for groundbreaking advances in the field, from lab-scale to scale-up. This roadmap provides an extensive review by experts in academia and industry of the current state of the art in 2021 and the different research directions and strategies currently underway to improve the performance of sodium-ion batteries. The aim is to provide an opinion with respect to the current challenges and opportunities, from the fundamental properties to the practical applications of this technology., The authors gratefully acknowledge RS2E and Alistore-ERI for funding their research into Na-ion batteries. The funding received from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No. 646433 (NAIADES), the Swedish Research Council, the Swedish Energy Agency (#37671-1), and the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS), are all gratefully acknowledged. The many fruitful discussions within ALISTORE-ERI, and especially with M Rosa Palacín, have been most valuable. P J is also grateful for the continuous support from several of the Chalmers Areas of Advance: Materials Science and Energy. Funding from the European Union’s innovation program H2020 is acknowledged: H2020-MSCA-COFUND-2016 (DOC-FAM, Grant Agreement No. 754397). A Ponrouch is grateful to the Spanish Ministry for Economy, Industry and Competitiveness Severo Ochoa Programme for Centres of Excellence in R&D (SEV-2015-0496).
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- 2021
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27. LaSrCo
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Zheying, Xu, Robert G, Palgrave, and Michael A, Hayward
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Topochemical reduction of the
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- 2020
28. Structure and magnetism of the Rh
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Nijat, Hasanli, Alex, Scrimshire, Paul A, Bingham, Robert G, Palgrave, and Michael A, Hayward
- Abstract
Synchrotron X-ray powder diffraction data indicate that La0.5Sr0.5Mn0.5Rh0.5O3 and La0.5Sr0.5Fe0.5Rh0.5O3 adopt distorted perovskite structures (space group Pnma) with A-site and B-site cation disorder. A combination of XPS and 57Fe Mössbauer data indicate the transition metal cations in the two phases adopt Mn3+/Rh4+ and Fe3+/Rh4+ oxidation state combinations respectively. Transport data indicate both phases are insulating, with ρ vs. T dependences consistent with 3D variable-range hopping. Magnetisation data reveal that La0.5Sr0.5Mn0.5Rh0.5O3 adopts a ferromagnetic state below Tc ∼ 60 K, which is rationalized on the basis of coupling via a dynamic Jahn-Teller distortion mechanism. In contrast, magnetic data reveal La0.5Sr0.5Fe0.5Rh0.5O3 undergoes a transition to a spin-glass state at T ∼ 45 K, attributed to frustration between nearest-neighbour Fe-Rh and next-nearest-neighbour Fe-Fe couplings.
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- 2020
29. Bandgap lowering in mixed alloys of Cs2Ag(SbxBi1−x)Br6 double perovskite thin films
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Zahra Andaji-Garmaroudi, Jaakko Julin, Zewei Li, Daniel W. Davies, David O. Scanlon, Robert L. Z. Hoye, Robert G. Palgrave, Richard H. Friend, Mojtaba Abdi-Jalebi, Seán R. Kavanagh, Aron Walsh, Mikko Laitinen, Mark A. Isaacs, Mari Napari, Downing College, Cambridge, Royal Academy of Engineering, Royal Academy Of Engineering, and Isaac Newton Trust
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Work (thermodynamics) ,Materials science ,Band gap ,FOS: Physical sciences ,Halide ,02 engineering and technology ,0915 Interdisciplinary Engineering ,010402 general chemistry ,01 natural sciences ,Atomic orbital ,General Materials Science ,Thin film ,0912 Materials Engineering ,Condensed Matter - Materials Science ,Range (particle radiation) ,Condensed matter physics ,Renewable Energy, Sustainability and the Environment ,Bowing ,Materials Science (cond-mat.mtrl-sci) ,0303 Macromolecular and Materials Chemistry ,General Chemistry ,021001 nanoscience & nanotechnology ,cond-mat.mtrl-sci ,0104 chemical sciences ,Pairing ,0210 nano-technology - Abstract
Halide double perovskites have gained significant attention, owing to their composition of low-toxicity elements, stability in air and long charge-carrier lifetimes. However, most double perovskites, including Cs2AgBiBr6, have wide bandgaps, which limit photo conversion efficiencies. The bandgap can be reduced through hallowing with Sb3+, but Sb-rich alloys are difficult to synthesise due to the high formation energy of Cs2AgSbBr6, which itself has a wide bandgap. We develop a solution-based route to synthesis phase-pure Cs2Ag(SbxBi1-x)Br6 thin films, with the mixing parameter x continuous varying over the entire composition range. We reveal that the mixed alloys (x between 0.5 and 0.9) demonstrate smaller bandgaps (as low as 2.08 eV) than the pure Sb- (2.18 eV) and Bi-based (2.25 eV) compounds, with strong deviation from Vegard's law. Through in-depth computations, we propose that bandgap lowering arises from the Type II band alignment between Cs2AgBiBr6 and Cs2AgSbBr6. The energy mismatch between the Bi and Sb s and p atomic orbitals, coupled with their non-linear mixing, results in the alloys adopting a smaller bandgap than the pure compounds. Our work demonstrates an approach to achieve bandgap reduction and highlights that bandgap bowing may be found in other double perovskite alloys by pairing together materials forming a Type II band alignment., Comment: 28 pages, 4 figures
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- 2020
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30. An X-ray photoelectron spectroscopy study of ionic liquids based on a bridged dicationic moiety
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Anham Zafar, Tim Evans, Robert G Palgrave, and Imtiaz- ud-Din
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General Chemistry - Abstract
A series of imidazolium and pyridinium-based bridged dicationic ionic liquids have been analysed using X-ray photoelectron spectroscopy. The different electronic environments of the dications have been investigated and a robust fitting model for the carbon C1s region has also been developed. The relative positions of different C1s components and N1s of dications have been determined and their complex C1s photoemission spectra produced from both aromatic and aliphatic carbon states giving photoemission peaks in the binding energy range of 289.0–283.9 eV. A contemporary fitting approach has been applied to a different set of environments which allowing comparison of the binding energies of cationic components of imidazolium and pyridinium-based dicationic ionic liquids. The experimental stoichiometry of all the carbons and nitrogens have also been calculated from XP spectra of the dicationic ionic liquids.
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- 2022
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31. Facile synthesis of mesoporous VO2 nanocrystals by a cotton-template method and their enhanced thermochromic properties
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Gopinathan Sankar, Xiujian Zhao, Shouqin Tian, Baoshun Liu, Robert G. Palgrave, Haizheng Tao, Shaowen Wu, and Ivan P. Parkin
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Spin coating ,Nanocomposite ,Renewable Energy, Sustainability and the Environment ,Nanoparticle ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Hydrothermal circulation ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Chemical engineering ,Thin film ,0210 nano-technology ,Mesoporous material ,human activities ,circulatory and respiratory physiology ,Monoclinic crystal system ,Template method pattern - Abstract
As a very promising thermochromic material, VO2 (M/R) (Monoclinic/Rutile) has not been widely applied in smart windows due to its intrinsic low solar modulation (ΔTsol) and low luminous transmission (Tlum). To address this issue, porous structures have been introduced into the VO2 film. Herein, mesoporous VO2 powders with pore size of about 2–10 nm were synthesized using cotton as template by hydrothermal methods. The pore and crystal size of the synthesized VO2 powders can be reliably controlled by the hydrothermal temperature. The mesoporous VO2 powders were mixed with PVP to prepare the VO2-based nanocomposite films by spin coating. The VO2-based films show a better performance between ΔTsol and Tlum than that appeared in previous reports. Especially, a larger pore size could lead to a higher visible transmittance and a larger crystal size would facilitate the enhancement in the solar modulation. In this sense, the VO2-based film obtained at the hydrothermal temperature of 180 °C exhibits an outstanding thermochromic performance with ΔTsol of 12.9% and Tlum up to 56.0% due to a larger crystal size and pore size. Therefore, this synthetic route shows a potential method for the application of mesoporous VO2 powders for solar control coatings.
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- 2018
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32. Shedding Light on the Protonation States and Location of Protonated N Atoms of Adenine in Metal–Organic Frameworks
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Tu N. Nguyen, Samantha L. Anderson, John Bacsa, Berend Smit, Matthew J. Rosseinsky, Andrzej Gładysiak, Kyriakos C. Stylianou, Robert G. Palgrave, and Peter G. Boyd
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chemistry.chemical_classification ,Denticity ,Protonation ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Article ,0104 chemical sciences ,Coordination complex ,Inorganic Chemistry ,Metal ,Crystallography ,Molecular geometry ,chemistry ,X-ray photoelectron spectroscopy ,Transition metal ,visual_art ,visual_art.visual_art_medium ,Metal-organic framework ,Physical and Theoretical Chemistry ,0210 nano-technology - Abstract
We report the syntheses and structures of five metal–organic frameworks (MOFs) based on transition metals (NiII, CuII, and ZnII), adenine, and di-, tri-, and tetra-carboxylate ligands. Adenine, with multiple N donor sites, was found to coordinate to the metal centers in different binding modes including bidentate (through N7 and N9, or N3 and N9) and tridentate (through N3, N7, and N9). Systematic investigations of the protonation states of adenine in each MOF structure via X-ray photoelectron spectroscopy revealed that adenine can be selectively protonated through N1, N3, or N7. The positions of H atoms connected to the N atoms were found from the electron density maps, and further supported by the study of C–N–C bond angles compared to the literature reports. DFT calculations were performed to geometrically optimize and energetically assess the structures simulated with different protonation modes. The present study highlights the rich coordination chemistry of adenine and provides a method for the determination of its protonation states and the location of protonated N atoms of adenine within MOFs, a task that would be challenging in complicated adenine-based MOF structures., The protonation states and positions of hydrogen atoms in five adenine-based metal−organic frameworks were revealed using geometrical studies based on single-crystal XRD data supported by XPS spectra and DFT calculations.
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- 2018
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33. Degradation of Layered Oxide Cathode in a Sodium Battery: A Detailed Investigation by X‐Ray Tomography at the Nanoscale
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Vittorio Marangon, Daniele Di Lecce, Jusef Hassoun, Mark A. Isaacs, Paul R. Shearing, and Robert G. Palgrave
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Materials science ,layered cathodes ,FOS: Physical sciences ,Applied Physics (physics.app-ph) ,02 engineering and technology ,Electrolyte ,tomography ,010402 general chemistry ,Electrochemistry ,7. Clean energy ,01 natural sciences ,Na-ion batteries ,law.invention ,X-ray photoelectron spectroscopy ,intercalation ,law ,Physics - Chemical Physics ,XPS ,General Materials Science ,Polarization (electrochemistry) ,Chemical Physics (physics.chem-ph) ,cathode degradation ,X-ray imaging ,Ambientale ,Physics - Applied Physics ,General Chemistry ,021001 nanoscience & nanotechnology ,Microstructure ,Cathode ,0104 chemical sciences ,Chemical engineering ,Electrode ,Particle size ,0210 nano-technology - Abstract
The degradation mechanism in a sodium cell of a layered Na0.48Al0.03Co0.18Ni0.18Mn0.47O2 (NCAM) cathode with P3/P2 structure is investigated by revealing the changes in microstructure and composition upon cycling. The work aims to rationalize the gradual performance decay and the alteration of the electrochemical response in terms of polarization, voltage signature, and capacity loss. Spatial reconstructions of the electrode by X-ray computed tomography at the nanoscale supported by quantitative and qualitative analyses show fractures and deformations in the cycled layered metal-oxide particles, as well as inorganic side compounds deposited on the material. These irreversible morphological modifications reflect structural heterogeneities across the cathode particles due to formation of various domains with different Na+ intercalation degrees. Besides, X-ray photoelectron spectroscopy data suggest that the latter inorganic species in the cycled electrode are mainly composed of NaF, Na2O, and NaCO3 formed by parasitic electrolyte decomposition. The precipitation of these insulating compounds at the electrode/electrolyte interphase and the related structural stresses induced in the material lead to a decrease in cathode particle size and partial loss of electrochemical activity. The retention of the NCAM phase after cycling suggests that electrolyte upgrade may improve the performance of the cathode to achieve practical application for sustainable energy storage.
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- 2021
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34. Phase quantification by X-ray photoemission valence band analysis applied to mixed phase TiO2 powders
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Andrew C. Breeson, Gopinathan Sankar, Robert G. Palgrave, and Gregory K. L. Goh
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Anatase ,Materials science ,Analytical chemistry ,General Physics and Astronomy ,Fraction (chemistry) ,02 engineering and technology ,Surfaces and Interfaces ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Spectral line ,0104 chemical sciences ,Surfaces, Coatings and Films ,Condensed Matter::Materials Science ,Rutile ,Phase (matter) ,Photocatalysis ,Valence band ,Mixed phase ,0210 nano-technology - Abstract
A method of quantitative phase analysis using valence band X-ray photoelectron spectra is presented and applied to the analysis of TiO2 anatase-rutile mixtures. The valence band spectra of pure TiO2 polymorphs were measured, and these spectral shapes used to fit valence band spectra from mixed phase samples. Given the surface sensitive nature of the technique, this yields a surface phase fraction. Mixed phase samples were prepared from high and low surface area anatase and rutile powders. In the samples studied here, the surface phase fraction of anatase was found to be linearly correlated with photocatalytic activity of the mixed phase samples, even for samples with very different anatase and rutile surface areas. We apply this method to determine the surface phase fraction of P25 powder. This method may be applied to other systems where a surface phase fraction is an important characteristic.
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- 2017
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35. Identification of the Mechanism of Electrocatalytic Ozone Generation on Ni/Sb-SnO2
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David A. C. Manning, Pierrot S. Attidekou, Russell G. Egdell, Paul A. Christensen, Robert G. Palgrave, and S. Maneelok
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Ozone ,Analytical chemistry ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Ion ,chemistry.chemical_compound ,Nickel ,General Energy ,chemistry ,X-ray photoelectron spectroscopy ,Antimony ,Organic chemistry ,Crystallite ,Physical and Theoretical Chemistry ,0210 nano-technology ,Thermal analysis ,BET theory - Abstract
This paper reports a systematic study of the codoping of SnO2 with Sb and Ni to identify the mechanism responsible for the electrocatalytic generation of ozone on Ni/Sb-SnO2. On the basis of interpretation of a combination of X-ray diffraction, BET surface area measurements (N2), and thermal analysis, the formation of ozone appears to take place on particle surfaces of composite Sb-SnO2 grains and is controlled by diffusion of OH along internal crystallite surfaces within the grain. Sb-doped SnO2 is inactive with respect to ozone evolution in the absence of Ni, demonstrating a synergic interaction between nickel and antimony. From X-ray photoelectron spectroscopy (XPS) investigations, Sb(V) ions substitute for Sn(IV) in the lattice with a preference for centrosymmetric coordination sites, while the Sb(III) ions occur at grain surfaces or boundaries. Ni was not detected by XPS, being located in the subsurface region at concentrations below the detection limit of the instrument. In addition to identificatio...
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- 2017
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36. Particle size, morphology and phase transitions in hydrothermally produced VO2(D)
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Robert G. Palgrave, Ivan P. Parkin, Raul Quesada-Cabrera, Gopinathan Sankar, Gregory K. L. Goh, Michael Powell, and Diana Teixeira
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Chemistry ,Annealing (metallurgy) ,musculoskeletal, neural, and ocular physiology ,Transition temperature ,Analytical chemistry ,Nanoparticle ,Vanadium ,chemistry.chemical_element ,Nanotechnology ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,Ammonium metavanadate ,Materials Chemistry ,Hydrothermal synthesis ,Pentoxide ,Particle size ,0210 nano-technology ,human activities ,circulatory and respiratory physiology - Abstract
Different morphologies and sizes of VO2(D) particles were synthesised via hydrothermal synthesis using ammonium metavanadate (NH4VO3) or vanadium pentoxide (V2O5) as a vanadium precursor. By adjusting the concentration of vanadium precursors and the pH of the starting solution, a variety of morphologies and sizes of VO2(D) particles from 20 nm to 3 μm could be produced. A flower-shape morphology was obtained under strongly acidic conditions, passing through star-shape particles of 1 μm at pH 2.5 and finally obtaining homogeneous round balls of around 3 μm at pH 6.9. Nanoparticles were produced hydrothermally using V2O5 as a precursor and hydrazine as a reducing agent. The transition from VO2(D) to thermochromic VO2(R) in micron scale particles occurred at 350 °C under vacuum. However, the nanoparticles of VO2(D) had a significantly lower VO2(D) to thermochromic VO2(R) transition temperature of 165 °C after annealing for only a few minutes. This is, to our knowledge, the lowest annealing temperature and time reported in the literature in order to obtain a thermochromic VO2 material via another VO2 phase. After the conversion of VO2(D) microparticles to thermochromic VO2(R), the metal to insulator transition temperature is 61 ± 1 °C for the heating cycle and 53 ± 1 °C for the cooling cycle. However, VO2(R) nanoparticles showed a significantly reduced metal insulator transition temperature of 59 ± 1 °C and 42 ± 1 °C for the cooling cycle lower than that reported in the literature for bulk VO2. This is important due to the need for having a compound with a switching temperature closer to room temperature to be used in smart window devices for energy consumption. W-VO2(D) star shape microparticle samples were prepared using 2–7 at% of the dopant (using ammonium metavanadate as a precursor), although unexpectedly this does not seem to be a viable route to a reduced metal to insulator transition in this system.
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- 2017
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37. Quantifying the Polymeric Capping of Nanoparticles with X-Ray Photoelectron Spectroscopy
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Stanislav V. Sokolov, Eden E. L. Tanner, Richard G. Compton, Kamonwad Ngamchuea, and Robert G. Palgrave
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Tetrafluoroborate ,Materials science ,Ethylene ,technology, industry, and agriculture ,chemistry.chemical_element ,Nanoparticle ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Oxygen ,Atomic and Molecular Physics, and Optics ,Silver nanoparticle ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,X-ray photoelectron spectroscopy ,PEG ratio ,Ionic liquid ,Physical and Theoretical Chemistry ,0210 nano-technology ,Nuclear chemistry - Abstract
X-ray photoelectron spectroscopy was used to characterise silver nanoparticles capped with poly(ethylene) glycol (PEG) in a room-temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4 ]). The amounts of oxygen and silver present in nanoparticles capped with different molecular weight thiolated PEG chains were monitored, and the number of thiolated PEG chains per nanoparticle was calculated, an in situ characterisation not previously possible.
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- 2018
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38. Bioinspired Polymerization of Quercetin to Produce a Curcumin-Loaded Nanomedicine with Potent Cytotoxicity and Cancer-Targeting Potential in Vivo
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Suhair Sunoqrot, Khuloud T. Al-Jamal, Eveen Al-Shalabi, Lina Hasan Ibrahim, Tahany Al-Debsi, Adam A. Walters, Robert G. Palgrave, and Farid N. Faruqu
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cancer targeting ,0206 medical engineering ,Biomedical Engineering ,02 engineering and technology ,quercetin ,Biomaterials ,chemistry.chemical_compound ,In vivo ,bioinspired nanoparticles ,medicine ,curcumin ,Cytotoxicity ,green chemistry ,technology, industry, and agriculture ,Cancer ,021001 nanoscience & nanotechnology ,medicine.disease ,020601 biomedical engineering ,Polymerization ,chemistry ,Cancer research ,Curcumin ,Nanomedicine ,0210 nano-technology ,Quercetin ,Drug carrier - Abstract
Nanomedicine has had a profound impact on the treatment of many diseases, especially cancer. However, synthesis of multifunctional nanoscale drug carriers often requires multistep coupling and purification reactions, which can pose major scale-up challenges. Here, we leveraged bioinspired oxidation-triggered polymerization of catechols to synthesize nanoparticles (NPs) from the plant polyphenol quercetin (QCT) loaded with a hydrophobic anticancer drug, curcumin, and functionalized with poly(ethylene glycol) (PEG) for steric stabilization in one reaction step. NPs were formed by base-catalyzed oxidative self-polymerization of QCT in the presence of curcumin and thiol-terminated PEG upon mixing in a universal solvent (dimethyl sulfoxide), followed by self-assembly with the gradual addition of water. Dynamic light scattering and X-ray photoelectron spectroscopy were used to confirm NP PEGylation. Drug loading was verified by UV-vis spectroscopy. Curcumin-loaded NPs were efficiently internalized by CT26 murine colon cancer cells as determined by flow cytometry and confocal microscopy. NPs also demonstrated sustained release and potent cytotoxicity in vitro. Moreover, in vivo imaging of CT26 tumor-bearing Balb/c mice following tail vein injection of DiR-labeled QCT NPs showed steady tumor accumulation of the NPs up to 24 h. This was further supported by significant tumor uptake of curcumin-loaded QCT NPs as measured by flow cytometry analysis of tumor homogenates. Our findings present a greener synthetic route for the fabrication of drug-loaded surface-functionalized NPs from poorly water-soluble plant polyphenols such as QCT as promising anticancer delivery systems.
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- 2019
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39. Electron spectroscopy of ionic liquids: experimental identification of atomic orbital contributions to valence electronic structure
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Kevin R. J. Lovelock, Patricia A. Hunt, Ignacio J. Villar-Garcia, Richard A. Bourne, Richard M. Fogarty, Karsten Handrup, David J. Payne, and Robert G. Palgrave
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CORE EXCITATIONS ,PHOTOELECTRON-SPECTROSCOPY ,SURFACE ,General Physics and Astronomy ,02 engineering and technology ,Electronic structure ,RESONANT AUGER-SPECTROSCOPY ,Physics, Atomic, Molecular & Chemical ,010402 general chemistry ,01 natural sciences ,Electron spectroscopy ,Ion ,chemistry.chemical_compound ,Condensed Matter::Materials Science ,Atomic orbital ,PHOTOIONIZATION ,Physics::Atomic and Molecular Clusters ,Physical and Theoretical Chemistry ,PHOTOEMISSION ,HOMO/LUMO ,IMIDAZOLIUM ,Valence (chemistry) ,Science & Technology ,Chemical Physics ,02 Physical Sciences ,Chemistry, Physical ,Physics ,Cationic polymerization ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Chemistry ,chemistry ,X-RAY-ABSORPTION ,Ionic liquid ,Physical Sciences ,Physical chemistry ,Condensed Matter::Strongly Correlated Electrons ,0210 nano-technology ,03 Chemical Sciences ,DECAY ,HYBRIDIZATION - Abstract
The atomic contributions to valence electronic structure for 37 ionic liquids (ILs) are identified using a combination of variable photon energy XPS, resonant Auger electron spectroscopy (RAES) and a subtraction method. The ILs studied include a diverse range of cationic and anionic structural moieties. We introduce a new parameter for ILs, the energy difference between the energies of the cationic and anionic highest occupied fragment orbitals (HOFOs), which we use to identify the highest occupied molecular orbital (HOMO). The anion gave rise to the HOMO for 25 of the 37 ILs studied here. For 10 of the ILs, the energies of the cationic and anionic HOFOs were the same (within experimental error); therefore, it could not be determined whether the HOMO was from the cation or the anion. For two of the ILs, the HOMO was from the cation and not from the anion; consequently it is energetically more favourable to remove an electron from the cation than the anion for these two ILs. In addition, we used a combination of area normalisation and subtraction of XP spectra to produce what are effectively XP spectra for individual ions; this was achieved for seven cations and 14 anions.
- Published
- 2019
40. Solvothermal water-diethylene glycol synthesis of LiCoPO4 and effects of surface treatments on lithium battery performance
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Samantha Soulé, Nuria Garcia-Araez, Robert G. Palgrave, John Owen, Andrew L. Hector, Michael G. Palmer, Min Zhang, Department of Chemistry, University of Southampton, University of Southampton, Department of Chemistry, University College London, and University College of London [London] (UCL)
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Materials science ,General Chemical Engineering ,Solvothermal synthesis ,Diethylene glycol ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,Thermal treatment ,[CHIM.MATE]Chemical Sciences/Material chemistry ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Lithium battery ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Coating ,Chemical engineering ,engineering ,Particle size ,0210 nano-technology ,Tin ,Carbon ,ComputingMilieux_MISCELLANEOUS - Abstract
Olivine-structured LiCoPO4 is prepared via a facile solvothermal synthesis, using various ratios of water/diethylene glycol co-solvent, followed by thermal treatment under Ar, air, 5%H2/N2 or NH3. The diethylene glycol plays an important role in tailoring the particle size of LiCoPO4. It is found that using a ratio of water/diethylene glycol of 1 : 6 (v/v), LiCoPO4 is obtained with a homogenous particle size of ∼150 nm. The bare LiCoPO4 prepared after heating in Ar exhibits high initial discharge capacity of 147 mA h g−1 at 0.1C with capacity retention of 70% after 40 cycles. This is attributed to the enhanced electronic conductivity of LiCoPO4 due to the presence of Co2P after firing under Ar. The effects of carbon, TiN and RuO2 coating are also examined. Contrary to other studies, it is found that the solvothermally synthesised LiCoPO4 samples produced here do not require conductive coatings to achieve good performance.
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- 2019
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41. Plasma Surface Modification of Polyhedral Oligomeric Silsequioxane-Poly(carbonate-urea) Urethane with Allylamine Enhances the Response and Osteogenic Differentiation of Adipose-Derived Stem Cells
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Deepak M. Kalaskar, Feras Alshomer, Camilo Chaves, and Robert G. Palgrave
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Materials science ,Scanning electron microscope ,Carbonates ,Adipose tissue ,Pilot Projects ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Allylamine ,Nanocomposites ,chemistry.chemical_compound ,Osteogenesis ,Polymer chemistry ,Urea ,Organosilicon Compounds ,General Materials Science ,chemistry.chemical_classification ,Polycarboxylate Cement ,Stem Cells ,Polymer ,021001 nanoscience & nanotechnology ,Plasma polymerization ,0104 chemical sciences ,chemistry ,Chemical engineering ,Cell culture ,Ninhydrin ,Surface modification ,0210 nano-technology - Abstract
This study present amino functionalization of biocompatible polymer polyhedral oligomeric silsequioxane-poly(carbonate-urea) urethane (POSS-PCU) using plasma polymerization process to induce osteogenic differentiation of adipose derived stem cells (ADSCs). Optimization of plasma polymerization process was carried out keeping cell culture application in mind. Thus, samples were rigorously tested for retention of amino groups under both dry and wet conditions. Physio-chemical characterization was carried out using ninhydrin test, X-ray photon spectroscopy, scanning electron microscopy, and static water contact analysis. Results from physio chemical characterization shows that functionalization of the amino group is not stable under wet conditions and optimization of plasma process is required for stable bonding of amino groups to the POSS-PCU polymer. Optimized samples were later tested in vitro in short and long-term culture to study differentiation of ADSCs on amino modified samples. Short-term cell culture shows that initial cell attachment was significantly (p0.001) improved on amine modified samples (NH2-POSS-PCU) compared to unmodified POSS-PCU. NH2-POSS-PCU samples also facilitates osteogenic differentiation of ADSCs as confirmed by immunological staining of cells for extracellular markers such as collagen Type I and osteopontin. Quantification of total collagen and ALP activity also shows significant (p0.001) increase on NH2-POSS-PCU samples compared to unmodified POSS-PCU. A pilot study also confirms that these optimized amino modified POSS-PCU samples can further be functionalized using bone inducing peptide such as KRSR using conventional wet chemistry. This further provides an opportunity for biofunctionalization of the polymer for various tissue specific applications.
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- 2016
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42. Intelligent Multifunctional VO2/SiO2/TiO2 Coatings for Self-Cleaning, Energy-Saving Window Panels
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Raul Quesada-Cabrera, Gopinathan Sankar, Ioannis Papakonstantinou, Robert G. Palgrave, Alaric Taylor, Diana Teixeira, Ivan P. Parkin, and Michael Powell
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Materials science ,business.industry ,General Chemical Engineering ,Oxide ,Vanadium ,chemistry.chemical_element ,Nanotechnology ,02 engineering and technology ,General Chemistry ,Chemical vapor deposition ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Air conditioning ,Physical vapor deposition ,Materials Chemistry ,Deposition (phase transition) ,Thin film ,0210 nano-technology ,business ,Monoclinic crystal system - Abstract
Monoclinic vanadium(IV) oxide (VO2) has received much attention for applications as intelligent solar control coatings, with the potential to reduce the need for both heating and air conditioning loads within building infrastructure. Chemical vapor deposition, a high-throughput industrially scalable method, is an ideal technology for the deposition of VO2 thin films on window panels. However, these films suffer from poor adhesion and are chemically susceptible to attack. In addition, the VO2 films with optimum solar modulation are unfortunately translucent, restraining their commercial use in energy-efficient fenestration. In this work, multifunctional, robust, layered VO2/SiO2/TiO2 films were quickly deposited on glass substrates using atmospheric-pressure chemical vapor deposition and fully characterized using structural, vibrational spectroscopy, and electron microscopy techniques. The VO2/SiO2/TiO2 thin films were designed to exhibit excellent solar modulation properties as well as high transparency a...
- Published
- 2016
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43. Probing the chemical structure of monolayer covalent-organic frameworks grown via Schiff-base condensation reactions
- Author
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Matthew O. Blunt, Alex M. Ganose, Niall Goodeal, Hugo Bronstein, Ying Chen, Ya Hu, Robert G. Palgrave, Bronstein, Hugo [0000-0003-0293-8775], and Apollo - University of Cambridge Repository
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Chemical structure ,02 engineering and technology ,010402 general chemistry ,Photochemistry ,0305 Organic Chemistry ,01 natural sciences ,Catalysis ,law.invention ,chemistry.chemical_compound ,X-ray photoelectron spectroscopy ,law ,Monolayer ,Materials Chemistry ,Organic chemistry ,0306 Physical Chemistry (incl. Structural) ,Schiff base ,Metals and Alloys ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensation reaction ,Porphyrin ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry ,Covalent bond ,Ceramics and Composites ,Scanning tunneling microscope ,0210 nano-technology - Abstract
Two-dimensional covalent-organic frameworks (2D-COFs) on surfaces offer a facile route to new 2D materials. Schiff-base condensation reactions have proven to be an effective fabrication route for such materials. We present scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) studies of porphyrin 2D-COFs grown at a solid-vapour interface. XPS shows that covalent links between porphyrins consist of a mixture of imines and hemiaminals, a non-conjugated intermediate in the Schiff-base condensation reaction. These results demonstrate that environmental conditions during growth can have an important impact on the chemical composition of Schiff-base 2D-COFs.
- Published
- 2016
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44. Solvothermal water-diethylene glycol synthesis of LiCoPO
- Author
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Min, Zhang, Nuria, Garcia-Araez, Andrew L, Hector, John R, Owen, Robert G, Palgrave, Michael G, Palmer, and Samantha, Soulé
- Abstract
Olivine-structured LiCoPO
- Published
- 2018
45. Singlet oxygen and the origin of oxygen functionalities on the surface of carbon electrodes
- Author
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Richard G. Compton, Christopher Batchelor-McAuley, Korbua Chaisiwamongkhol, and Robert G. Palgrave
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010405 organic chemistry ,Chemistry ,Singlet oxygen ,chemistry.chemical_element ,General Medicine ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,Photochemistry ,01 natural sciences ,Oxygen ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,Electrode ,Light sensitive ,0210 nano-technology ,Carbon - Abstract
The generation of oxygen-containing functionalities on pristine carbon surfaces is investigated and shown to be light sensitive, specifically to infra-red radiation. A mechanistic route involving singlet oxygen, 1 O2 , is proposed and evidenced.
- Published
- 2018
46. Aerosol-assisted chemical vapor deposition of V2O5 cathodes with high rate capabilities for magnesium-ion batteries
- Author
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Chenglin Jia, Shiny Mathew, Andreas Kafizas, Charalampos Drosos, Benjamin Moss, Dimitra Vernardou, and Robert G. Palgrave
- Subjects
Battery (electricity) ,Technology ,Materials science ,Energy & Fuels ,Materials Science ,Mg-ion battery ,Energy Engineering and Power Technology ,Vanadium ,chemistry.chemical_element ,Materials Science, Multidisciplinary ,02 engineering and technology ,Electrolyte ,Chemical vapor deposition ,engineering.material ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,09 Engineering ,CARBON ,V2O5 ,Aqueous electrolyte ,Coating ,Pentoxide ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Magnesium ion ,INTERCALATION PROPERTIES ,Science & Technology ,Energy ,Renewable Energy, Sustainability and the Environment ,Chemistry, Physical ,ELECTROCHEMICAL INSERTION ,PERFORMANCE ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Chemistry ,chemistry ,Chemical engineering ,Aerosol-assisted chemical vapor deposition (AACVD) ,Physical Sciences ,engineering ,Cathode ,0210 nano-technology ,03 Chemical Sciences ,BEHAVIOR ,ELECTROLYTE - Abstract
The growth of orthorhombic vanadium pentoxide nanostructures was accomplished using an aerosol-assisted chemical vapor deposition process. These materials showed excellent electrochemical performance for magnesium-ion storage in an aqueous electrolyte; showing specific discharge capacities of up to 427 mAh g−1 with a capacity retention of 82% after 2000 scans under a high specific current of 5.9 A g−1. The high rate capability suggested good structural stability and high reversibility. We believe the development of low-cost and large-area coating methods, such as the technique used herein, will be essential for the upscalable fabrication of next-generation rechargeable battery technologies.
- Published
- 2018
47. A Nature-Inspired Conjugated Polymer for High Performance Transistors and Solar Cells
- Author
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Raja Shahid Ashraf, Nilushi Wijeyasinghe, David M.E. Freeman, Hugo Bronstein, Tobin J. Marks, Mohammed Al-Hashimi, Robert G. Palgrave, Kealan J. Fallon, Iain McCulloch, Thomas D. Anthopoulos, Nir Yaacobi-Gross, Fallon, Kealan [0000-0001-6241-6034], Bronstein, Hugo [0000-0003-0293-8775], and Apollo - University of Cambridge Repository
- Subjects
chemistry.chemical_classification ,Organic electronics ,3403 Macromolecular and Materials Chemistry ,Organic field-effect transistor ,Polymers and Plastics ,34 Chemical Sciences ,business.industry ,Ambipolar diffusion ,Organic Chemistry ,Nanotechnology ,Polymer ,Chromophore ,4016 Materials Engineering ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Photovoltaics ,Materials Chemistry ,Thiophene ,business ,Absorption (electromagnetic radiation) ,40 Engineering - Abstract
A novel, highly soluble chromophore for use in organic electronics based on an indigoid structure is reported. Copolymerization with thiophene affords an extremely narrow band gap polymer with a maximum absorption at ∼800 nm. The novel polymer exhibits high crystallinity and high ambipolar transport in OFET devices of 0.23 cm2 V–1 s–1 for holes and 0.48 cm2 V–1 s–1 for electrons. OPV device efficiencies up to 2.35% with light absorbance up to 950 nm demonstrate the potential for this novel chromophore in near-IR photovoltaics.
- Published
- 2018
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48. Atomic charges of sulfur in ionic liquids: experiments and calculations
- Author
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Kevin R. J. Lovelock, Paul Thompson, Rebecca Rowe, Matthew T. Clough, Agnieszka Brandt, Richard P. Matthews, Emily F. Smith, Richard A. Bourne, Thomas W. Chamberlain, Paul J. Corbett, Claire R. Ashworth, Richard M. Fogarty, Patricia A. Hunt, and Robert G. Palgrave
- Subjects
0306 Physical Chemistry (Incl. Structural) ,Binding energy ,Analytical chemistry ,0904 Chemical Engineering ,OXIDATION-STATE ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,BINDING-ENERGIES ,Ion ,DENSITY-FUNCTIONAL THEORY ,AUGER-PARAMETER ,Physics::Atomic and Molecular Clusters ,Physics::Atomic Physics ,Physical and Theoretical Chemistry ,CATION-ANION INTERACTIONS ,Auger electron spectroscopy ,Science & Technology ,Chemical Physics ,Chemistry ,Chemistry, Physical ,Atoms in molecules ,GAUSSIAN-BASIS SETS ,021001 nanoscience & nanotechnology ,XANES ,0104 chemical sciences ,MOLECULAR-ORBITAL METHODS ,ELECTRONIC-STRUCTURE ,13. Climate action ,Physical Sciences ,RAY PHOTOELECTRON-SPECTROSCOPY ,FORCE-FIELD ,0210 nano-technology ,CHELPG ,Effective atomic number ,Natural bond orbital - Abstract
Experimental near edge X-ray absorption fine structure (NEXAFS) spectra, X-ray photoelectron (XP) spectra and Auger electron spectra are reported for sulfur in ionic liquids (ILs) with a range of chemical structures. These values provide experimental measures of the atomic charge in each IL and enable the evaluation of the suitability of NEXAFS spectroscopy and XPS for probing the relative atomic charge of sulfur. In addition, we use Auger electron spectroscopy to show that when XPS binding energies differ by less than 0.5 eV, conclusions on atomic charge should be treated with caution. Our experimental data provides a benchmark for calculations of the atomic charge of sulfur obtained using different methods. Atomic charges were computed for lone ions and ion pairs, both in the gas phase (GP) and in a solvation model (SMD), with a wide range of ion pair conformers considered. Three methods were used to compute the atomic charges: charges from the electrostatic potential using a grid based method (ChelpG), natural bond orbital (NBO) population analysis and Bader’s atoms in molecules (AIM) approach. By comparing the experimental and calculated measures of the atomic charge of sulfur, we provide an order for the sulfur atoms, ranging from the most negative to the most positive atomic charge. Furthermore, we show that both ChelpG and NBO are reasonable methods for calculating the atomic charge of sulfur in ILs, based on the agreement with both the XPS and NEXAFS spectroscopy results. However, the atomic charges of sulfur derived from ChelpG are found to display significant, non-physical conformational dependence. Only small differences in individual atomic charge of sulfur were observed between lone ion (GP) and ion pair IL(SMD) model systems, indicating that ion–ion interactions do not strongly influence individual atomic charges.
- Published
- 2018
49. Electronic and surface properties of Ga-doped In2O3 ceramics
- Author
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Anna Regoutz, Stephen J. Skinner, David J. Payne, Helena Téllez, David O. Scanlon, Graeme W. Watson, Russell G. Egdell, David J. Morgan, and Robert G. Palgrave
- Subjects
Chemistry ,Band gap ,Doping ,Analytical chemistry ,General Physics and Astronomy ,Surfaces and Interfaces ,General Chemistry ,Condensed Matter Physics ,Molecular physics ,Surfaces, Coatings and Films ,Band bending ,X-ray photoelectron spectroscopy ,Low-energy ion scattering ,Density functional theory ,Spectroscopy ,Lone pair - Abstract
The limit of solubility of Ga2O3 in the cubic bixbyite In2O3 phase was established by X-ray diffraction and Raman spectroscopy to correspond to replacement of around 6% of In cations by Ga for samples prepared at 1250 °C. Density functional theory calculations suggest that Ga substitution should lead to widening of the bulk bandgap, as expected from the much larger gap of Ga2O3 as compared to In2O3. However both diffuse reflectance spectroscopy and valence band X-ray photoemission reveal an apparent narrowing of the gap with Ga doping. It is tentatively concluded that this anomaly arises from introduction of Ga+ surface lone pair states at the top of the valence band and structure at the top of the valence band in Ga-segregated samples is assigned to these lone pair states. In addition photoemission reveals a broadening of the valence band edge. Core X-ray photoemission spectra and low energy ion scattering spectroscopy both reveal pronounced segregation of Ga to the ceramic surface, which may be linked to both relief of strain in the bulk and the preferential occupation of surface sites by lone pair cations. Surprisingly Ga segregation is not accompanied by the development of chemically shifted structure in Ga 2p core XPS associated with Ga+. However experiments on ion bombarded Ga2O3, where a shoulder at the top edge of the valence band spectra provide a clear signature of Ga+ at the surface, show that the chemical shift between Ga+ and Ga3+ is too small to be resolved in Ga 2p core level spectra. Thus the failure to observe chemically shifted structure associated with Ga+ is not inconsistent with the proposal that band gap narrowing is associated with lone pair states at surfaces and interfaces.
- Published
- 2015
- Full Text
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50. Experimental validation of calculated atomic charges in ionic liquids
- Author
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Agnieszka Brandt-Talbot, Robert G. Palgrave, Richard A. Bourne, Richard M. Fogarty, Richard P. Matthews, Kevin R. J. Lovelock, Claire R. Ashworth, Tom Vander Hoogerstraete, and Patricia A. Hunt
- Subjects
Population ,General Physics and Astronomy ,OXIDATION-STATE ,02 engineering and technology ,Physics, Atomic, Molecular & Chemical ,010402 general chemistry ,01 natural sciences ,09 Engineering ,DENSITY-FUNCTIONAL THEORY ,ABSORPTION-SPECTROSCOPY ,MOLECULES ,XPS ,Physical and Theoretical Chemistry ,education ,Spectroscopy ,CATION-ANION INTERACTIONS ,IMIDAZOLIUM ,education.field_of_study ,Science & Technology ,ANALOGS ,02 Physical Sciences ,Chemical Physics ,Chemistry, Physical ,Physics ,Atoms in molecules ,Charge density ,021001 nanoscience & nanotechnology ,Electrostatics ,0104 chemical sciences ,Chemistry ,ELECTRONIC-STRUCTURE ,Chemical physics ,Physical Sciences ,RAY PHOTOELECTRON-SPECTROSCOPY ,Density functional theory ,0210 nano-technology ,03 Chemical Sciences ,CHELPG ,Natural bond orbital - Abstract
A combination of X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy have been used to provide an experimental measure of nitrogen atomic charge in nine ionic liquids (ILs). These experimental results are used to validate charges calculated with three computational methods: charges from electrostatic potentials using a grid-based method (ChelpG), natural bond orbital (NBO) population analysis and the atoms in molecules (AIM) approach. By combining these results with those from a previous study on sulfur, we find that ChelpG charges provide the best description of charge distribution in ILs. However, we find that ChelpG charges can lead to significant conformational dependence and therefore advise that small differences in ChelpG charges (
- Published
- 2017
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