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The Copper oxide (CuO) NPs sensing film has been synthesized on glass substrate by using catalyst free thermal evaporation of the Cu powder followed by annealing in air atmosphere at 700°C temperature and further characterization with X-ray diffraction, scanning electron microscopy and EDAX analysis for confirming its structure, morphology and composition. The chemoresistive gas sensing performance of CuO NPs were studied towards various oxidizing and reducing gases. The experimental results reveal that, CuO NPs were vastly sensitive and selective towards NO2 gas than other test gases. CuO NPs exhibit maximum response of 29% for 100ppm NO2 gas with very fast response time at optimal 1500C temperature. The CuO NPs sensor manifests remarkably enhanced sensing performance, including good response and recovery time suggestive of the promising application of the CuO NPs in the gas sensing.

Gas sensing properties of metal oxide semiconductors draw high attention due to their simple fabricating methods, and low cost, chemical, and physical properties. In general, a high bandgap (>2 eV) can cause them to react in the UV region through the electromagnetic spectrum. Controlling the UV-photodetection and gas sensing ability of MoO2-MoO3 thin film through tungsten (W) doping of different ratios have been reported here. The preparation of these films was grown using a reactive magnetron sputtering system with different power sputtering of W-content. The bandgap calculations showed that the samples have a wide bandgap value. A small particle size of 8nm was observed through high W doping concentration which enhanced these materials toward high efficient gas sensing and UV photodetector applications. The UV optical sensor exhibits a high responsivity value of 2500A/W and an external quantum efficiency (EQE) value of 5x109 at 365nm. Also, an increase in the photocurrent gain value with increasing the W amount with a maximum value of 0.13, while a photocurrent of 1mA was observed. On the other hand, a fast-response/recovery time-based CO2 gas sensor of less than 10 sec was observed. The thin-film sensors showed well-defined adsorption and desorption kinetics in a CO2 environment with a p-type chemisorption behavior., Metal oksit yarı iletkenlerin gaz algılama özellikleri, basit üretim yöntemleri ve düşük maliyeti, kimyasal ve fiziksel özellikleri nedeniyle büyük ilgi görmektedir. Genel olarak, yüksek bir bant aralığı (>2 eV), elektromanyetik spektrum yoluyla UV bölgesinde reaksiyona girmelerine neden olabilir. Farklı oranlarda tungsten (W) dopingi yoluyla MoO2-MoO3 ince filmin UV foto algılama ve gaz algılama yeteneğinin kontrol edilmesi burada rapor edilmiştir. Bu filmlerin hazırlanması, W içeriğinin farklı güç püskürtmeli reaktif magnetron püskürtme sistemi kullanılarak büyütüldü. Bant aralığı hesaplamaları, örneklerin geniş bir bant aralığı değerine sahip olduğunu göstermiştir. Bu malzemeleri yüksek verimli gaz algılama ve UV fotodetektör uygulamalarına doğru geliştiren yüksek W katkı konsantrasyonu yoluyla 8 nm'lik küçük bir parçacık boyutu gözlemlendi. UV optik sensör, 365nm'de 2500A/W'lik yüksek bir duyarlılık değeri ve 5x109'luk bir harici kuantum verimliliği (EQE) değeri sergiler. Ayrıca, 1mA'lık bir fotoakım olurken, maksimum 0.13 değerinde W miktarı arttıkça fotoakım kazanç değerinde bir artış gözlemlendi. Öte yandan, 10 saniyeden kısa bir hızlı yanıt/kurtarma süresine dayalı CO2 gaz sensörü gözlendi. İnce film sensörleri, p-tipi kimyasal adsorpsiyon davranışına sahip bir CO2 ortamında iyi tanımlanmış adsorpsiyon ve desorpsiyon kinetiği gösterdi.

Driving oxygen evolution reaction (OER) at extremely low overpotential and the blockage of oxygen gas inside the catalytic material leads to the deactivation of catalytic activity, therefore it is an essential step in electrochemical energy conversion systems, but still very challenging task. The clay minerals including bentonite and kaolinite are rich with plenty of active centers and favorable chemical composition for the catalysis applications but limited by the insulating properties, thus they cannot be used as an electrode material for the water splitting. The unique presence of clay minerals in the form of pencil graphite rod (PGR) and its attractive architecture enabled us to exploit advantageous features and use them as an in situ electrode for growth of metal oxide nanostructures for the electrolysis applications. The naturally inherent presence of SiO2 favors the catalytic properties and durability of the electrode whereas the MgO produces the abundant oxygen vacancies and Co3+ ions for OER process. Herein, we present a facile approach of using PGR as host substrate and co-catalyst for the loading of Co3O4, NiCo2O4 and NiO nanostructures and the modified electrode carried high porosity for easily bubbling of oxygen gas, plenty of intrinsic active centers coming from both clay minerals and metal oxides for excellent OER process. The fabricated electrode is physically well-characterized, and it has a natural ability to sustain a long term stability even at higher current densities and industrial electrolyzer conditions. The NiCo2O4/PGR, Co3O4/PGR, and NiO/PGR electrodes exhibit an overpotential of 234, 242 and 272 mV respectively at a current density of 100 mAcm−2 in 1.0 M KOH electrolytic solution. The presence of large number of oxygen vacancies through SiO2 and MgO, high Ni2+/Ni3+ and Co3+/Co2+ ratios, multi metal centers, large specific surface area, high pore volume, high electrochemical active surface area and fast charge transport within the NiCo2O4/PGR are the main reasons for its superfast OER kinetics. Thus, the proposed method of electrode design will pave a potential way for high performance electrochemical devices like metal air batteries, fuel cell and supercapacitors.

In this work, we identify the importance of C60 and compact-TiO2 (cTiO2) as electron transport layers on the device performance of coevaporated n–i–p perovskite solar cells. We found (1) a synergetic effect between both layers when extracting the charges and (2) that optimization of the C60 layer is essential for obtaining devices with enhanced device performance. In particular, we found that a C60 layer of an optimum thickness (20 nm), an additional charge transport resistance is observed by impedance analysis, indicating that devices with nonoptimized C60 thickness could limit the fabrication of highly efficient perovskite solar cells. N.K., C.M., A.O.A., and F.F.-S. thank the European Union′s Horizon 2020 research nos. 764787 and 763977. H.K. acknowledges the support of the H2020 program for Solar-ERANET funding of the BOBTANDEM (2019-2022) A.A.S. and C.I. acknowledge the Swiss National Science Foundation (SNSF) funding through Synergia Grant EPISODE (grant no. CRSII5_171000). The authors thank the project German Research Foundation (DFG) (Projekt number 424101351)–Swiss National Foundation (SNF) (200021E_186390). A.O.A. and F.F.-S. acknowledge Ministerio de Economía y Competitividad (MINECO) from Spain under the project ENE2017-85087-C3-1-R and Generalitat Valenciana under the project PROMETEO/2020/028 for financial support.

Metal oxides are ideal for the fabrication of gas sensors: they are sensitive to many gases while allowing the device to be simple, tiny, and inexpensive. Nonetheless, their lack of selectivity remains a limitation. In order to achieve good selectivity in applications with many possible interfering gases, the sensors are inserted into an electronic nose that combines the signals from nonselective sensors and analyzes them with multivariate statistical algorithms in order to obtain selectivity. This review analyzes the scientific articles published in the last decade regarding electronic noses based on metal oxide nanowires. After a general introduction, Section 2 discusses the issues related to poor intrinsic selectivity. Section 3 briefly reviews the main algorithms that have hitherto been used and the results they can provide. Section 4 classifies the recent literature into fundamental research, agrifood, health, security. In Section 5, the literature is analyzed regarding the metal oxides, the surface decoration nanoparticles, the features that differentiate the sensors in a given array, the application for which the device was developed, the algorithm used, and the type of information obtained. Section 6 concludes by discussing the present state and points out the requirements for their use in real-world applications.

BackgroundAcute phase response (APR) is characterized by a change in concentration of different proteins, including C-reactive protein and serum amyloid A (SAA) that can be linked to both exposure to metal oxide nanomaterials and risk of cardiovascular diseases. In this study, we intratracheally exposed mice to ZnO, CuO, Al2O3, SnO2 and TiO2 and carbon black (Printex 90) nanomaterials with a wide range in phagolysosomal solubility. We subsequently assessed neutrophil numbers, protein and lactate dehydrogenase activity in bronchoalveolar lavage fluid, Saa3 and Saa1 mRNA levels in lung and liver tissue, respectively, and SAA3 and SAA1/2 in plasma. Endpoints were analyzed 1 and 28 days after exposure, including histopathology of lung and liver tissues.ResultsAll nanomaterials induced pulmonary inflammation after 1 day, and exposure to ZnO, CuO, SnO2, TiO2 and Printex 90 increased Saa3 mRNA levels in lungs and Saa1 mRNA levels in liver. Additionally, CuO, SnO2, TiO2 and Printex 90 increased plasma levels of SAA3 and SAA1/2. Acute phase response was predicted by deposited surface area for insoluble metal oxides, 1 and 28 days post-exposure.ConclusionSoluble and insoluble metal oxides induced dose-dependent APR with different time dependency. Neutrophil influx, Saa3 mRNA levels in lung tissue and plasma SAA3 levels correlated across all studied nanomaterials, suggesting that these endpoints can be used as biomarkers of acute phase response and cardiovascular disease risk following exposure to soluble and insoluble particles Background: Acute phase response (APR) is characterized by a change in concentration of different proteins, including C-reactive protein and serum amyloid A (SAA) that can be linked to both exposure to metal oxide nanomaterials and risk of cardiovascular diseases. In this study, we intratracheally exposed mice to ZnO, CuO, Al2O3, SnO2 and TiO2 and carbon black (Printex 90) nanomaterials with a wide range in phagolysosomal solubility. We subsequently assessed neutrophil numbers, protein and lactate dehydrogenase activity in bronchoalveolar lavage fluid, Saa3 and Saa1 mRNA levels in lung and liver tissue, respectively, and SAA3 and SAA1/2 in plasma. Endpoints were analyzed 1 and 28 days after exposure, including histopathology of lung and liver tissues. Results: All nanomaterials induced pulmonary inflammation after 1 day, and exposure to ZnO, CuO, SnO2, TiO2 and Printex 90 increased Saa3 mRNA levels in lungs and Saa1 mRNA levels in liver. Additionally, CuO, SnO2, TiO2 and Printex 90 increased plasma levels of SAA3 and SAA1/2. Acute phase response was predicted by deposited surface area for insoluble metal oxides, 1 and 28 days post-exposure. Conclusion: Soluble and insoluble metal oxides induced dose-dependent APR with different time dependency. Neutrophil influx, Saa3 mRNA levels in lung tissue and plasma SAA3 levels correlated across all studied nanomaterials, suggesting that these endpoints can be used as biomarkers of acute phase response and cardiovascular disease risk following exposure to soluble and insoluble particles.

A main challenge on the way to viable photoelectrochemical (PEC) technologies is to develop inexpensive photoelectrodes that can deliver a stable performance with reasonable solar-to-fuel conversion efficiency on a timescale of years. Semiconductor photoelectrodes are at the core of PEC technologies, as they are responsible for harvesting light and for the generation of charge carriers that drive surface redox reactions. High-performance, durable photoelectrodes are typically composed not only of semiconductor light absorbers but also of additional materials that are necessary to provide complementary functionalities, e.g., conductive substrates (charge collectors), protection (or passivation) layers, cocatalysts, and photosensitizers, among others. In this chapter, we describe structure, materials, preparation and performance of photoelectrodes, focusing on metal oxide semiconductors.

Increasing the performance of heat exchangers is one of industry’s most pressing challenges. Pulsating heat pipes (PHPs), as a novel technology with high-performance, are broadly used in solar distilled water and systems solar water heaters. In the present work, the impact of three nanofluids including zirconium dioxide (ZrO2), bismuth ferrite (BiFeO3)/ZrO2 (ZBF), and ZrO2/SiO2composites under concentrations of 0.25, 0.5, and 1.0 g/L was investigated on the PHPs performance. The thermal resistance of the base fluid and the produced nanofluids was compared under a constant filling ratio of 50% and different input powers to the evaporator. The obtained results revealed that the use of working fluid such as nanofluids increased the heat transfer of PHPs in comparison to the base fluid and reduced the thermal resistance. Among the nanofluids used, the concentration of 0.25 g/L of the prepared nanocomposites provided the best performance. The resistance of the PHPs at some fluxes was reduced by up to 40%. In general, from the point of view of materials engineering, the structure of compounds used in nanofluids should have low thermal resistance, high thermal conductivity, and low viscosity. From a chemical point of view, using metals and compounds with high thermal conductivity is essential due to significant electron exchange.

Title: Metal oxide thin film transistors for CMOS applications Author: N.C.A. van Fraassen CMOS technology based on oxide thin film transistors (TFTs) is essential to reduce the power consumption and increase the complexity of low-cost (flexible) processors. These processors have the potential to create ultralow-cost (~1 pence) chips that can turn everyday objects into smart-objects. This thesis presents research on the development of all-oxide CMOS technology. N-type amorphous indium-silicon-oxide (a-ISO) and p-type tin monoxide (SnO) TFTs were fabricated and studied in detail. Both these oxides are excellent candidates for low-cost, low-power, flexible CMOS technology which is essential to reduce the power consumption of flexible processors. All oxide CMOS inverters were created by connecting n-type a-ISO and p-type SnO TFTs. By carefully tuning the geometric aspect ratio of the inverter, a rail-to-rail voltage swing was demonstrated for supply voltages as low as 1 V. We investigated how changing the width-to-length ratio (W/L) of p-type SnO TFTs affects the characteristics of the all-oxide CMOS inverter. Typically, W/L of the lower mobility p-type TFT (n-type for organics) is scaled up (inversely with mobility) to match the higher on-current of the n-type (p-type); this is also common for silicon CMOS technology. In this work it is shown that this method is unsuitable for transistors where not only the on-current, but also the off-current, scales with W/L - including flexible p-type metal-oxide and n-type organic TFTs. The concept of an optimal geometric aspect ratio is introduced that can be applied universally to silicon, metal-oxide and organic complementary inverters. This ratio determines the W/L of the p-type (n-type) transistor that maximises the inverter efficiency represented by the average switching current divided by the static currents. Notably, this work shows that reducing W/L of metal-oxide p-type TFTs increases the inverter efficiency, while reducing the area compared to simply scaling up W/L inversely with mobility. A high inverter efficiency is critical to reduce static power consumption and increase the gate density of flexible processors. Lastly, we investigated a novel memristor-transistor inverter, where the p-type TFT in the standard CMOS configuration is replaced by a memristor. We looked in detail at the fabrication method and inverter design of the memristor-transistor combination. The required switching characteristics of the memristor are investigated by modelling a current- and voltage-controlled ‘reset’ as well as a voltage-swept ‘set’. The results show it is critical that the memristor can be set by sweeping the input voltage across a small range in the reverse direction. To achieve this, precise control and excellent repeatability of the memristor set (and reset) voltage are required., Tis work was supported by the UKRI Engineering and Physical Sciences Research Council through the Centre of Doctoral Training in Integrated Photonic and Electronics Systems (EP/L015455/1) and grant EP/P027032/1.

Water plays pivotal roles in tailoring reaction pathways in many important reactions, including cascade C-C bond formation and oxygen elimination. Herein, a kinetic study combined with complementary analyses (DRIFTS, isotopic study, 1H solid-state magic angle spinning nuclear magnetic resonance) and density functional theory (DFT) calculations are performed to elucidate the roles of water in cascade acetone-to-isobutene reactions on a Zn x Zr y O z mixed metal oxide with balanced Lewis acid-base pairs. Our results reveal that the reaction follows the acetone-diacetone alcohol-isobutene pathway. Isobutene is produced through an intramolecular rearrangement of the eight-membered ring intermediate formed via the adsorption of diacetone alcohol on the Lewis acid-base pairs in the presence of cofed water. OH adspecies, formed by the dissociative adsorption of water on the catalyst surface, were found to distort diacetone alcohol's hydroxyl functional group toward its carbonyl functional group and facilitate the intramolecular rearrangement of diacetone alcohol to form isobutene. In the absence of water, diacetone alcohol binds strongly to the Lewis acid site, e.g., at a Zr4+ site, via its carbonyl functional group, leading to its dramatic structural distortion and further dehydration reaction to form mesityl oxide as well as subsequent polymerization reactions and the formation of coke. The present results provide insights into the cooperative roles of water and Lewis acid-base pairs in catalytic upgrading of biomass to fuels and chemicals.

Perovskite solar cells (PSCs) are a promising area of research among different new generations of photovoltaic technologies. Their manufacturing costs make them appealing in the PV industry compared to their alternatives. Although PSCs offer high efficiency in thin layers, they are still in the development phase. Hence, optimizing the thickness of each of their layers is a challenging research area. In this paper, we investigate the effect of the thickness of each layer on the photoelectric parameters of n-ZnO/p-CH3NH3PbI3/p-NiOx solar cell through various simulations. Using the Sol–Gel method, PSC structure can be formed in different thicknesses. Our aim is to identify a functional connection between those thicknesses and the optimum open-circuit voltage and short-circuit current. Simulation results show that the maximum efficiency is obtained using a perovskite layer thickness of 200 nm, an electronic transport layer (ETL) thickness of 60 nm, and a hole transport layer (HTL) thickness of 20 nm. Furthermore, the output power, fill factor, open-circuit voltage, and short-circuit current of this structure are 18.9 mW/cm2, 76.94%, 1.188 V, and 20.677 mA/cm2, respectively. The maximum open-circuit voltage achieved by a solar cell with perovskite, ETL and HTL layer thicknesses of (200 nm, 60 nm, and 60 nm) is 1.2 V. On the other hand, solar cells with the following thicknesses, 800 nm, 80 nm, and 40 nm, and 600 nm, 80 nm, and 80 nm, achieved a maximum short-circuit current density of 21.46 mA/cm2 and a fill factor of 83.35%. As a result, the maximum value of each of the photoelectric parameters is found in structures of different thicknesses. These encouraging results are another step further in the design and manufacturing journey of PSCs as a promising alternative to silicon PV.

The search for inexpensive, environmentally friendly, and highly effective catalysts to activate C-H bonds in propane dehydrogenation (PDH) reactions is still a major challenge. Co-based catalysts have gained significant attention in recent years due to their excellent ability to activate C-H bonds and their high selectivity towards olefins, despite being a non-noble and environmentally unfriendly metal. However, further improvements are necessary for practical utilization, particularly in terms of activity and anti-carbon deposition capacity. In this study, we synthesized Al2O3 nanorods with abundant pentacoordinated Al3+ (Al3+penta) sites. The supported Co on the Al2O3 nanorod (Co/Al2O3-NR) exhibited higher selectivity (>96% propylene selectivity) and stability (deactivation rate 0.15 h−1) compared to Co supported on an Al2O3 nanosheet with fewer pentacoordinated Al3+ sites. Various characterizations confirmed that Co(II) mainly exists as CoAl2O4 rather than Co3O4 in the form of Co/Al2O3-NR, which inhibits the reduction of Co(II) to Co0 and accordingly improves catalyst stability.

Methanol, naturally present in small quantities in the distillation of alcoholic beverages, can lead to serious health problems. When it exceeds a certain concentration, it causes blindness, organ failure, and even death if not recognized in time. Analytical techniques such as chromatography are used to detect dangerous concentrations of methanol, which are very accurate but also expensive, cumbersome, and time-consuming. Therefore, a gas sensor that is inexpensive and portable and capable of distinguishing methanol from ethanol would be very useful. Here, we present a resistive gas sensor, based on tin oxide nanowires, that works in a thermal gradient. By combining responses at various temperatures and using machine learning algorithms (PCA, SVM, LDA), the device can distinguish methanol from ethanol in a wide range of concentrations (1–100 ppm) in both dry air and under different humidity conditions (25–75% RH). The proposed sensor, which is small and inexpensive, demonstrates the ability to distinguish methanol from ethanol at different concentrations and could be developed both to detect the adulteration of alcoholic beverages and to quickly recognize methanol poisoning.

Reasonable structural design and composition control are the dominant factors for tuning the electromagnetic absorbing properties of materials. In this paper, microspheres composed of NiO, Ni, and Co3O4 nanoparticles (NCMO) were successfully synthesized using a mild oxidation method. Benefiting from the multi-component composition and a unique microstructure, the RLmin of CNMO can reach −46.8 dB at 17 GHz, with an effective absorption bandwidth of 4.1 GHz (13.9–18 GHz). The absorbing properties and the absorbing mechanism analysis showed that the microsphere-structured NCMO composed of multi-component nanoparticles enhanced the interface polarization, thereby improving the absorption performance. This research provides a new avenue for MOF-derived oxide materials with excellent electromagnetic wave absorbing properties.

Background: Green synthesized nanoparticles (NPs) from agricultural wastes is an area of great interest due to it is eco-friendly and profitable. Zinc oxide is an inorganic UV-filter commonly used as UV-blocker in a different industry. Methods: Zinc oxide nanoparticles (ZnO NPs) were successfully biosynthesized using Zn(NO3)2 as a substrate by polyphenol enriched fraction (PEF) of pomegranate peel. The biological activity of ZnO NPs was evaluated using MBC and MIC tests for antibacterial and DPPH assay for antioxidant potential. Sunscreen potential of NPs was determined after applying them in water-in-oil emulsions. Results: UV-Vis and FT-IR spectroscopy techniques confirmed the formation of ZnO NPs. FE-SEM characterized the morphology and purity of the biosynthesized NPs with EDAX and XRD data. The average crystalline size of ZnO NPs was found to be 22 nm. FT-IR spectroscopy revealed the role of phenolic compounds in the formation and stability of ZnO NPs. The antibacterial activity of PEF and its biosynthesized ZnO was evaluated against Staphylococcus aureus and Escherichia coli. The prepared NPs showed a higher antibacterial effect than the commercial ZnO NPs. Interestingly, the antioxidant activity was also detected for obtained NPs. The PEF powder also exhibited higher antibacterial and antioxidant activity than the standards. Furthermore, the in vitro sun protection factors were estimated after applying NPs in water-in-oil emulsions. Conclusion: This study highlighted the possibility of using PEF of pomegranate peel for the biosynthesis of ZnO NPs as well as applying its NPs in sunscreens to achieve a safe alternative to harmful chemical UV-filters commonly used in cosmetics.

A new method for stirring under high pressure conditions has been developed and tested. The key component is a Teflon cell assembly equipped with magnetic stirring function, which is capable to operate across a wide pressure range, up to at least 2 GPa, in a large volume press. The setup enables adjustable stirrer rotation rate and detection of stirring in a sample,e.g.to observe liquid-solid phase transitions at high pressure. The viscosity limit of stirring is ca. 500 times that of water at room temperature (i.e.similar to 500 mPas). Moreover, we show that zinc oxide nanoparticles hydrothermally synthesized at 0.5 GPa and 100 degrees C under stirring conditions show an order of magnitude smaller size (100 nm) compared to those synthesized under non-stirring conditions (1 mu m). The wide pressure range for stirring of viscous media opens interesting possibilities to produce novel materials via hydrothermal synthesis and chemical reactions.

Recently, hierarchical hybrid structures based on the combination of semiconductor micro/nanostructures and noble metal nanoparticles have become a hot research topic in the area of surface-enhanced Raman scattering (SERS). In this work, two core-satellite nanostructures of metal oxide/metal nanoparticles were successfully introduced into SERS substrates, assembling monodispersed small silver nanoparticles (Ag NPs) on large polydispersed ZnO nanospheres (p-ZnO NSs) or monodispersed ZnO nanospheres (m-ZnO NSs) core. The p-ZnO NSs and m-ZnO NSs were synthesized by the pyrolysis method without any template. The Ag NPs were prepared by the thermal evaporation method without any annealing process. An ultralow limit of detection (LOD) of 1 × 10−13 M was achieved in the two core-satellite nanostructures with Rhodamine 6G (R6G) as the probe molecule. Compared with the silicon (Si)/Ag NPs substrate, the two core-satellite nanostructures of Si/p-ZnO NSs/Ag NPs and Si/m-ZnO NSs/Ag NPs substrates have higher enhancement factors (EF) of 2.6 × 108 and 2.5 × 108 for R6G as the probe molecule due to the enhanced electromagnetic field. The two core-satellite nanostructures have great application potential in the low-cost massive production of large-area SERS substrates due to their excellent SERS effect and simple preparation process without any template.

Funder: Alphasense Limited, Selectivity for specific analytes and high‐temperature operation are key challenges for chemiresistive‐type gas sensors. Complementary hybrid materials, such as reduced graphene oxide (rGO) decorated with metal oxides enables realization of room‐temperature sensors with enhanced sensitivity. However, sensor training to identify target gases and accurate concentration measurement from gas mixtures still remain very challenging. This work proposes hybridization of rGO with CuCoO x binary metal oxide as a sensing material. Highly stable, room‐temperature NO2 sensors with a 50 ppb of detection limit is demonstrated using inkjet printing. A framework is then developed for machine‐intelligent recognition with good visibility to identify specific gases and predict concentration under an interfering atmosphere from a single sensor. Using ten unique parameters extracted from the sensor response, the machine learning‐based classifier provides a decision boundary with 98.1% accuracy, and is able to correctly predict previously unseen NO2 and humidity concentrations in an interfering environment. This approach enables implementation of an intelligent platform for printable, room‐temperature gas sensors in a mixed environment irrespective of ambient humidity.

Extensive studies have been conducted on different kinds of polymers, their composites, and multifunctionalities, depending on their structural features. Metal oxides and their polymer nanocomposites offer technological characteristics due to mechanical, electrical, and electronic properties. Nanofibers have considerable morphological significance, owing to their structural identity and behavior. Polymer composite nanofibers can be rodlike, porous, hollow, or core-shell, depending on the fabrication techniques that are used. Recently, electrospinning has been emerged as an important tool to fabricate microfibrous or nanofibrous membranes of polymers, biopolymers, and their composites. However, this procedure can be challenging, owing to the related cost and required external conditions, such as solvents and heat. Composite nanofibers can find applications in membrane, biomedical and pharmaceutical, food packaging, and environmental applications. This chapter discusses selected composite nanofibers and their characteristics, taking into account the electroactivity, elastomeric nature, and biofriendliness of the polymers. 2022 Elsevier Inc. All rights reserved. Scopus

The controlled and efficient formation of oxygen vacancies on the surface of metal oxide semiconductors is required for their use in gas sensors. This work addresses the gas-sensing behaviour of tin oxide (SnO2) nanoparticles for nitrogen oxide (NO2), NH3, CO, and H2S detection at various temperatures. Synthesis of SnO2 powder and deposition of SnO2 film is conducted using sol-gel and spin-coating methods, respectively, as these methods are cost-effective and easy to handle. The structural, morphological, and optoelectrical properties of nanocrystalline SnO2 films were studied using XRD, SEM, and UV-visible characterizations. The gas sensitivity of the film was tested by a two-probe resistivity measurement device, showing a better response for the NO2 and outstanding low-concentration detection capacity (down to 0.5 ppm). The anomalous relationship between specific surface area and gas-sensing performance indicates the SnO2 surface’s higher oxygen vacancies. The sensor depicts a high sensitivity at 2 ppm for NO2 with response and recovery times of 184 s and 432 s, respectively, at room temperature. The result demonstrates that oxygen vacancies can significantly improve the gas-sensing capability of metal oxide semiconductors.

One of the ideal energy carriers for the future is hydrogen. It has a high energy density and is a source of clean energy. A crucial step in the development of the hydrogen economy is the safety and affordable storage of a large amount of hydrogen. Thus, owing to its large storage capacity, good reversibility, and low cost, Magnesium hydride (MgH2) was taken into consideration. Unfortunately, MgH2 has a high desorption temperature and slow ab/desorption kinetics. Using the ball milling technique, adding cobalt lanthanum oxide (LaCoO3) to MgH2 improves its hydrogen storage performance. The results show that adding 10 wt.% LaCoO3 relatively lowers the starting hydrogen release, compared with pure MgH2 and milled MgH2. On the other hand, faster ab/desorption after the introduction of 10 wt.% LaCoO3 could be observed when compared with milled MgH2 under the same circumstances. Besides this, the apparent activation energy for MgH2–10 wt.% LaCoO3 was greatly reduced when compared with that of milled MgH2. From the X-ray diffraction analysis, it could be shown that in-situ forms of MgO, CoO, and La2O3, produced from the reactions between MgH2 and LaCoO3, play a vital role in enhancing the properties of hydrogen storage of MgH2.

Magnesium hydrides (MgH2) have drawn a lot of interest as a promising hydrogen storage material option due to their good reversibility and high hydrogen storage capacity (7.60 wt.%). However, the high hydrogen desorption temperature (more than 400 °C) and slow sorption kinetics of MgH2 are the main obstacles to its practical use. In this research, nickel zinc oxide (Ni0.6Zn0.4O) was synthesized via the solid-state method and doped into MgH2 to overcome the drawbacks of MgH2. The onset desorption temperature of the MgH2–10 wt.% Ni0.6Zn0.4O sample was reduced to 285 °C, 133 °C, and 56 °C lower than that of pure MgH2 and milled MgH2, respectively. Furthermore, at 250 °C, the MgH2–10 wt.% Ni0.6Zn0.4O sample could absorb 6.50 wt.% of H2 and desorbed 2.20 wt.% of H2 at 300 °C within 1 h. With the addition of 10 wt.% of Ni0.6Zn0.4O, the activation energy of MgH2 dropped from 133 kJ/mol to 97 kJ/mol. The morphology of the samples also demonstrated that the particle size is smaller compared with undoped samples. It is believed that in situ forms of NiO, ZnO, and MgO had good catalytic effects on MgH2, significantly reducing the activation energy and onset desorption temperature while improving the sorption kinetics of MgH2.

Nowadays, most medical-diagnostic, environmental monitoring, etc. devices employ sensors whose fabrication reproducibility and response repeatability assessment are crucial. The former consists of large-scale sensor manufacture through a standardized process with almost identical morphology and behavior, while the latter consists of giving the same response upon repeating the same stimulus. The thermo-activated chemoresistive sensors, which change their conductance by interacting with the molecules composing the surrounding gas, are currently employed in many devices: in particular, thick-film (SnTiNb)O2 nanosensors were demonstrated to be particularly suitable in the medical and biological fields. Therefore, a set of thirteen of them, randomly selected from the same screen-printing deposition, were laboratory tested, and the outcomes were statistically analyzed in order to assess their consistency. At first, the working temperature that maximized both the sensor sensitivity and response repeatability was identified. Then, the sensors were subjected to different gas concentrations and humidities at this optimal working temperature. It resulted in the (SnTiNb)O2 nanosensors detecting and discriminating CO concentrations as low as 1 ppm and at high humidity degrees (up to 40%) with high repeatability since the response relative standard error ranged from 0.8 to 3.3% for CO and from 3.6 to 5.4% for water vapor.

Tungsten oxide thin films have applications in various energy-related devices owing to their versatile semiconductor properties, which depend on the oxygen content and crystalline state. The concentration of electrons increases with intrinsic defects such as oxygen vacancies, which create new absorption bands that give rise to colored films. Disorders in the crystal structure produce additional changes in the electrical and optical characteristics. Here, WO3−x thin films are prepared on unheated glass substrates by reactive DC sputtering from a pure metal target, using the discharge power and the oxygen-to-argon pressure ratio as control parameters. A transition from amorphous to polycrystalline state is obtained by increasing the sputtering power and adjusting the oxygen content. The surface roughness is higher and the bandgap energy is lower for polycrystalline layers than for amorphous ones. Moreover, the electrical conductivity and sub-bandgap absorption increase as the oxygen content decreases.

Designing highly active material to fabricate a high-performance noninvasive wearable glucose sensor was of great importance for diabetes monitoring. In this work, we developed CuxO nanoflakes (NFs)/Cu nanoparticles (NPs) nanocomposites to serve as the sensing materials for noninvasive sweat-based wearable glucose sensors. We involve CuCl2 to enhance the oxidation of Cu NPs to generate Cu2O/CuO NFs on the surface. Due to more active sites endowed by the CuxO NFs, the as-prepared sample exhibited high sensitivity (779 μA mM−1 cm−2) for noninvasive wearable sweat sensing. Combined with a low detection limit (79.1 nM), high selectivity and the durability of bending and twisting, the CuxO NFs/Cu NPs-based sensor can detect the glucose level change of sweat in daily life. Such a high-performance wearable sensor fabricated by a convenient method provides a facile way to design copper oxide nanomaterials for noninvasive wearable glucose sensors.

JACS Au 2(4), 827 - 838 (2022). doi:10.1021/jacsau.1c00568, One can nowadays readily generate monodisperse colloidal nanocrystals, but a retrosynthetic analysis is still not possible since the underlying chemistry is often poorly understood. Here, we provide insight into the reaction mechanism of colloidal zirconia and hafnia nanocrystals synthesized from metal chloride and metal isopropoxide. We identify the active precursor species in the reaction mixture through a combination of nuclear magnetic resonance spectroscopy (NMR), density functional theory (DFT) calculations, and pair distribution function (PDF) analysis. We gain insight into the interaction of the surfactant, tri-n-octylphosphine oxide (TOPO), and the different precursors. Interestingly, we identify a peculiar X-type ligand redistribution mechanism that can be steered by the relative amount of Lewis base (L-type). We further monitor how the reaction mixture decomposes using solution NMR and gas chromatography, and we find that ZrCl4 is formed as a by-product of the reaction, limiting the reaction yield. The reaction proceeds via two competing mechanisms: E1 elimination (dominating) and SN1 substitution (minor). Using this new mechanistic insight, we adapted the synthesis to optimize the yield and gain control over nanocrystal size. These insights will allow the rational design and synthesis of complex oxide nanocrystals., Published by ACS Publications, Washington, DC

Surface-bound nanomaterials are widely used in clean energy techniques from lithium batteries, solar-driven evaporation in desalination to hydrogen production by photocatalytic electrolysis. Reactive surface nanodroplets may potentially streamline the process of fabrication of a range of surface-bound nanomaterials invoking biphasic reactions at interfaces. In this work, we demonstrate the feasibility of reactive surface nanodroplets for in-situ synthesis and anchoring of nanocaps of metal oxides with tailored porous structures. Spatial arrangement and surface coverage of nanocaps are predetermined during the formation of reactive nanodroplets, while the crystalline structures of metal oxides can be controlled by thermal treatment of organometallic nanodroplets produced from the biphasic reactions. Notably, tuning the ratio of reactive and non-reactive components in surface nanodroplets enables the formation of porous nanocaps that can double photocatalytic efficiency in the degradation of organic contaminants in water, compared to smooth nanocaps. In total, we demonstrate in-situ fabrication of four types of metal oxides in the shape of nanocaps. Our work shows that reactive surface nanodroplets may open a door to a general, fast and tuneable route for preparing surface-bound metal oxides. This fabrication approach may help develop new nanomaterials needed for photocatalytic reactions, wastewater treatment, optical focusing, solar energy conversion and other clean energy techniques.

Copper (Cu) is the most extensively used bactericide worldwide in many agricultural production systems. However, intensive application of Cu bactericide have increased the selection pressure toward Cu-tolerant pathogens, including Xanthomonas perforans, the causal agent of tomato bacterial spot. However, alternatives for Cu bactericides are limited and have many drawbacks including plant damage and inconsistent effectiveness under field conditions. Also, potential ecological risk on nontarget organisms exposed to field runoff containing Cu is high. However, due to lack of alternatives for Cu, it is still widely used in tomato and other crops around the world in both conventional and organic production systems. In this study, a Cu-tolerant X. perforans strain GEV485, which can tolerate eight tested commercial Cu bactericides, was used in all the field trials to evaluate the efficacy of MgO nanomaterial. Four field experiments were conducted to evaluate the impact of intensive application of MgO nanomaterial on tomato bacterial spot disease severity, and one field experiment was conducted to study the impact of soil accumulation of total and bioavailable Cu, Mg, Mn, and Zn. In the first two field experiments, twice-weekly applications of 200 μg/mL MgO significantly reduced disease severity by 29-38% less in comparison to a conventional Cu bactericide Kocide 3000 and 19-30% less in comparison to the water control applied at the same frequency (p = 0.05). The disease severity on MgO twice-weekly was 12-32% less than Kocide 3000 + Mancozeb treatment. Single weekly applications of MgO had 13-19% higher disease severity than twice weekly application of MgO. In the second set of two field trials, twice-weekly applications of MgO at 1000 μg/mL significantly reduced disease severity by 32-40% in comparison to water control applied at the same frequency (p = 0.05). There was no negative yield impact in any of the trials. The third field experiment demonstrated that application of MgO did not result in significant accumulation of total and bioavailable Mg, Mn, Cu, or Zn in the root-associated soil and in soil farther away from the production bed compared to the water control. However, Cu bactericide contributed to significantly higher Mn, Cu, and Zn accumulation in the soil compared to water control (p = 0.05). This study demonstrates that MgO nanomaterial could be an alternative for Cu bactericide and have potential in reducing risks associated with development of tolerant strains and for reducing Cu load in the environment.

The paper presents the implementation of a standard cell multigate fully synthesizable rail-to-rail dynamic voltage comparator. The dynamic voltage comparator works on deep sub-threshold supply voltage VDD =0.3 V with common mode inputs. The common-mode input range is VDD/2 with minimum input offset voltage ranging between 8mV to 28mV. Thus the circuit is simulated at 180nm Complementary Metal-Oxide Semiconductor (CMOS) process. Hence the dynamic voltage comparator has measured and tabulated by corresponding output voltage, power dissipation. But the performance of CMOS device is not good when compared with Fin Field-Effect Transistor (FinFET) device. The leakage current is more in CMOS devices while in FinFET device due to the control of multi-Gates on the channel, the leakage current is reduced. This will improve the power consumption in the FinFET device when compared to CMOS devices. The comparator results shows that CMOS device is inferior when compared with FinFET device comparator. For the implementation of the comparator Spice model were used in this work. The software used in the project is synopsis Hspice.

The strongly correlated electron material, vanadium dioxide (VO2), has seen considerable attention and research application in metal-oxide electronics due to its metal-to-insulator transition close to room temperature. Vacuum annealing a V2O5(010) single crystal results in Wadsley phases (VnO2n+1, n > 1) and VO2. The resistance changes by a factor of 20 at 342 K, corresponding to the metal-to-insulator phase transition of VO2. Macroscopic voltage-current measurements with a probe separation on the millimetre scale result in Joule heating-induced resistive switching at extremely low voltages of under a volt. This can reduce the hysteresis and facilitate low temperature operation of VO2 devices, of potential benefit for switching speed and device stability. This is correlated to the low resistance of the system at temperatures below the transition. High-resolution transmission electron microscopy measurements reveal a complex structural relationship between V2O5, VO2 and V6O13 crystallites. Percolation paths incorporating both VO2 and metallic V6O13 are revealed, which can reduce the resistance below the transition and result in exceptionally low voltage resistive switching.

Recently, the increasing demand for sustainable clean energy from non-fossil sources motivated the researchers in energy storage devices and supercapacitors are one of the most promising energy storage systems. In this study, flexible copper and nickel coated electrodes are fabricated for supercapacitor applications from Ethaline deep eutectic solvent media. Copper and nickel-based materials were potentiostatically electrodeposited on flexible graphite substrates from Ethaline ionic liquid containing copper and nickel ions. Cu–Ni coated graphite films were scanned in 1 M KOH from −0.7 V to 0.4 V at different scan rates ranging between 5 mV s−1 and 100 mV s−1. Fabricated Cu–Ni electrodes were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Copper and nickel formation ratios on graphite films at different deposition voltages were determined by EDX analysis. Cu–Ni coated graphite films applying −1.8 V deposition potential exhibited a maximum areal capacitance of 47.3 mF cm−2 at 5 mV s−1 scan rate. Galvanostatic charge-discharge curves of the electrodes obtained at different applied voltages confirms the supercapacitor behaviour of Cu–Ni coated films. One of the biggest issues regarding the use of supercapacitors in daily life is their self-discharge behaviour. Self-discharge curves of the Cu–Ni modified electrodes were illustrated that decreasing deposition potentials can decrease self-discharge problem. This research determines that Ethaline ionic liquid is a potential media for alloy-based electrodes in the usage of supercapacitor applications. © 2022 Elsevier Ltd

Rapid industrial development, vehicles, domestic activities and mishandling of garbage are the main sources of pollutants, which are destroying the atmosphere. There is a need to continuously monitor these pollutants for the safety of the environment and human beings. Conventional instruments for monitoring of toxic gases are expensive, bigger in size and time-consuming. Hybrid materials containing organic and inorganic components are considered potential candidates for diverse applications, including gas sensing. Gas sensors convert the information regarding the analyte into signals. Various polymeric/inorganic nanohybrids have been used for the sensing of toxic gases. Composites of different polymeric materials like polyaniline (PANI), poly (4-styrene sulfonate) (PSS), poly (3,4-ethylene dioxythiophene) (PEDOT), etc. with various metal/metal oxide nanoparticles have been reported as sensing materials for gas sensors because of their unique redox features, conductivity and facile operation at room temperature. Polymeric nanohybrids showed better performance because of the larger surface area of nanohybrids and the synergistic effect between polymeric and inorganic materials. This review article focuses on the recent developments of emerging polymeric/inorganic nanohybrids for sensing various toxic gases including ammonia, hydrogen, nitrogen dioxide, carbon oxides and liquefied petroleum gas. Advantages, disadvantages, operating conditions and prospects of hybrid composites have also been discussed.

Noble metal additives are widely used to improve the performance of metal oxide gas sensors, most prominently with palladium on tin oxide. Here, we photodeposit different quantities of Pd (0–3 mol%) onto nanostructured SnO2 and determine their effect on sensing acetone, a critical tracer of lipolysis by breath analysis. We focus on understanding the effect of operating temperature on acetone sensing performance (sensitivity and response/recovery times) and its relationship to catalytic oxidation of acetone through a packed bed of such Pd-loaded SnO2. The addition of Pd can either boost or deteriorate the sensing performance, depending on its loading and operating temperature. The sensor performance is optimal at Pd loadings of less than 0.2 mol% and operating temperatures of 200–262.5 °C, where acetone conversion is around 50%.

With the increasing application of active-matrix organic light-emitting diode (AMOLED) displays which are basically current-driven devices, a current-driven switch with larger current capability and higher frequency operation will prove to be beneficial. The growth of the Internet of Things (IoT) also results in increasing demand for transparent and conformable electronics, which requires materials that are highly uniform in electrical properties over large areas. All these factors have contributed to the prominent interest in metal oxides for semiconductor devices in the recent years, due to their high uniformity, high carrier mobility and low resistivity as a disordered material, when compared to the alternatives such as amorphous and polycrystalline silicon and organic semiconductors. In addition, metal oxides can be fabricated at much lower temperatures compared to high-temperature polycrystalline silicon (HTPS) and yet still achieve reasonable performance, enabling them to be easily deposited on flexible substrates like plastics and paper. Metal oxides generally with their larger band gaps are hard to be doped both n- and p-type, so heterojunctions are the feasible way to construct bipolar devices. Extensive literature review indicates that most research was focused on nickel oxide and oxides of copper for p-type materials, and variants of zinc oxide for n-type materials. This work identifies that, among these materials, cuprous oxide (Cu2O) and amorphous zinc-tin oxide (a-ZTO) are great materials with potential to form a good heterojunction, but this combination has been mostly unexplored. The simple mathematic model presented in this work shows that the charge carrier injection is possible with the proposed p-n heterojunction configuration, an important design requirement for heterojunction bipolar transistors which is the long-term goal of this work, but extreme care should be exercised in forming the junction as its quality heavily affects the injection efficiency. There is a need for a good quality thin film diode of Cu2O/a-ZTO p-n heterojunction as it is an essential component for the realization of flexible large-area electronics. However, this Cu2O/a-ZTO diode initially showed poor rectification characteristics. A systematic study of the origins of the poor performance is performed based on several experiments and measurements on the metal-semiconductor junctions and the p-n heterojunction. A good choice of metal contacts is crucial, and the contacts should be Ohmic so that diode rectification is only controlled by the p-n heterojunction. Experiments suggests that molybdenum and gold are good Ohmic contacts to a-ZTO and Cu2O, respectively. Further investigation and analysis are targeted on the properties of the p-n heterojunction. The results suggests that multiple carrier trapping and thermal release of carriers in defect states stemming from oxygen vacancies and oxygen related atomic coordination at the heterojunction interface is the primary cause of poor rectification. It is demonstrated that a plasma treatment is the simplest yet most effective way to optimize the population of oxygen vacancies at the heterojunction interface based on extensive material analyses, allowing a significant improvement in the diode performance with a much-enhanced rectification ratio from ~20 to 10 000, and a consequent facilitation of the next-generation of ubiquitous electronics. Finally, a more in-depth analysis on the p-n junction model, with a focus on capacitance-voltage (C-V) characteristics, is presented, with discussions on analytical derivations of the model and analyses of simulated junctions with various doping profiles. Some junction parameters in this thesis are obtained using the classical C-V model which was derived for more ideal situations. Hence, it is important to understand the accuracy of such a simple model when applied on real scenarios that differ significantly from the usual, basic assumptions. The analytical model of a p-n junction, even in only one dimension, is severely limited due to the complexity in mathematical representation. The results indicate that numerical simulation is the practical way to further investigate p-n junction properties. It is shown that the classical C-V analysis, which is simple, may be sufficient in extracting p-n junction parameters such as depletion depth and doping profiles, provided that the method’s limitations are understood. These findings allow readers further insight to the implementation challenges such as low rectification ratio of bipolar heterojunction thin film diodes made with Cu2O and a-ZTO, and future research direction for plausible solutions to these difficulties., Engineering and Physical Sciences Research Council (EPSRC) under grant no. EP/M013650/1 and EP/P027032/1; Cambridge Trust; Commonwealth Scholarship, funded by the UK government

Most metal–organic frameworks (MOFs) hardly maintain their physical and chemical properties after exposure to alkaline aqueous solutions, thus precluding their use as potential electrode materials for electrochemical energy storage devices. Here, we present the design and synthesis of a highly alkaline-stable metal oxide@MOF composite, Co3O4 nanocube@Co-MOF (Co3O4@Co-MOF), via a controllable and facile one-pot hydrothermal method under highly alkaline conditions. The obtained composite possesses exceptional alkaline stability, retaining its original structure in 3.0 M KOH for at least 15 days. Benefitting from the exceptional alkaline stability, unique structure, and larger surface area, the Co3O4@Co-MOF composite shows a specific capacitance as high as 1020 F g−1 at 0.5 A g−1 and a high cycling stability with only 3.3% decay after 5000 cycles at 5 A g−1. The as-constructed solid-state flexible device exhibits a maximum energy density of 21.6 mWh cm−3.

Tuning and optimization of electronic structures and related reaction energetics are critical toward the rational design of efficient electrocatalysts. Herein, experimental and theoretical calculation demonstrate the originally inert N site within polyaniline (PANI) can be activated for hydrogen evolution by proper d‐π interfacial electronic coupling with metal oxide. As a result, the as‐synthesized WO3 assemblies@PANI via a facile redox‐induced assembly and in situ polymerization, exhibits the electrocatalytic production of hydrogen better than other control samples including W18O49@PANI and most of the reported nobel‐metal‐free electrocatalysts, with low overpotential of 74 mV at 10 mA·cm−2 and small Tafel slope of 46 mV·dec−1 in 0.5M H2SO4 (comparable to commercial Pt/C). The general efficacy of this methodology is also validated by extension to other metal oxides such as MoO3 with similar improvements.

Nowadays the analysis of ambient atmosphere in order to monitor the presence of dangerous gases and volatile compounds is more and more important. For this reason, a network of tiny sensors capable to discriminate the presence of pollutants and distinguish them is crucial. We present here a resistive sensor based on a single tin oxide nanowire (60 nm in diameter and 3.5 μm long) that can detect the presence of different gases and estimate their concentration in the range of 1–50 ppm. The SnO2 nanowire (NW) is grown by chemical vapor deposition and then used to bridge to metal electrodes. Under a temperature gradient, 5 signals can be extracted, forming the thermal fingerprint of each specific gas that can be present in the measuring chamber. Applying machine learning algorithms to these thermal fingerprints, the system can recognize which gas is present in the chamber (with an 94.3% accuracy) and estimate the concentration of the gas (with an average error of 24.5%). The limit of detection has been found to be under 1 part per million for all the gases tested.

This study examines the effect of the annealing temperature on the initial electrical characteristics and photo-induced instabilities of amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs). The extracted electrical parameters from transfer curves suggest that a low-temperature treatment maintains a high density of defects in the IGZO bulk, whereas high-temperature annealing causes a quality degradation of the adjacent interfaces. Light of short wavelengths below 460 nm induces defect generation in the forward measurement and the leakage current increases in the reverse measurement, especially for the low-temperature-annealed device. The hysteresis after negative-bias-illumination-stress (NBIS) is quantitatively investigated by using the double-scan mode and a positive gate pulse. Despite the abnormal transfer properties in the low-temperature-treated device, the excited holes are identically trapped at the front interface irrespective of treatment temperature. NBIS-induced critical instability occurs in the high-temperature-annealed TFT.

Background: High concentration of phosphate has been threatening human health and the ecosystem. Adsorption is one of high-efficiency and low-cost techniques to reduce the concentration of phosphate. This mini review aims to summarize the recent development of adsorption materials for phosphate removal. Method: We conducted a detailed search of “adsorption of phosphate” in the published papers and the public patents on the adsorbents for phosphate based on Web of Science database in the period from January 1 2012 to December 31 2017. The corresponding literature was carefully evaluated and analyzed. Results: One hundred and forty one papers and twenty two recent patents were included in this review. An increased trend in scientific contributions was observed in the development of adsorption materials for phosphate removal. Three kinds of promising adsorbents: layered double hydroxides, natural materials, and metal oxides were paid special attention including removal mechanism, performance as well as the relationship between adsorption performance and structure. Both the chemical composition and the morphology play a key role in the removal capacity and rate. Conclusion: The findings of this review confirm the importance of phosphate removal, show the development trend of high-performance and low-cost adsorption materials for phosphate removal, and provide a helpful guide to design and fabricate high-efficiency adsorbents.

Properties of metal oxides, such as optical absorption, can be influenced through the sensitization with molecular species that absorb visible light. Molecular/solid interfaces of this kind are particularly suited for the development and design of emerging hybrid technologies such as dye-sensitized solar cells. A key optimization parameter for such devices is the choice of the compounds in order to control the direction and the intensity of charge transfer across the interface. Here, the deposition of two different molecular dyes, porphyrin and coumarin, as single-layered islands on a NiO(001) single crystal surface have been studied by means of non-contact atomic force microscopy at room temperature. Comparison of both island types reveals different adsorption and packing of each dye, as well as an opposite charge-transfer direction, which has been quantified by Kelvin probe force microscopy measurements.

Construction of low-cost and high-efficiency electrochromic electrodes with high color contrast and fast response time in electrochromic applications have led to a proliferation of studies in metal oxides. This research study presents a comprehensive overview of the electrochemical synthesis of nanoporous Cu-doped nickel oxide films on ITO-coated glass substrate and its electrochromic behavior in alkaline medium. X-ray diffraction analysis and scanning electron microscopy are used to determine the phase and morphology of the produced films. The films indicate uniform and good adhesion to the substrate. The electrochromic behavior of the deposited films is tested by means of cyclic voltammetry, chronocoulometry, repeating chronoamperometry, and electrochemical impedance spectroscopy measurements. The color change from dark brown to transparent appears reversibly well suitable under sequential potential from -0.2 to +1.0 V. After the Cu atoms incorporate into the host NiO matrix, noticeably enhancements are observed in optical modulation (57.1% at 550 nm), coloration efficiency (13.78 cm(2)/C) and response time (t(b) = 2.26 s and t(c) = 1.77 s) compared to its as-prepared NiO films. Energy level diagrams including fermi level, valance band edge and conduction band edge positions are presented based on the Mott-Schottky approximation and Tauc's method using absorbance data for the NiO and Cu:NiO films. The negative slope of the Mott-Schottky plot shows p-type conductivity for the films, and acceptor density is found as 4.44 x 10(19) cm(-3) and 5.41 x 10(19) cm(-3) for the NiO and Cu:NiO films, respectively. An equivalent electronic circuit is fitted using the measured Nyquist data of the NiO or Cu:NiO semiconductor/electrolyte system, and the calculated values of the circuit elements show significant sensitivity to the Cu doping. Therefore, our results make a major contribution to the research on energy-saving smart windows by demonstrating analyses in detail.

The number of excess electrons (NEE), as a descriptor, perfectly reproduces the OER volcano curve of TiO2(110) plotted using ΔGO – ΔGOH., The development of a universal activity descriptor like the d-band model for transition metal catalysts is of great importance to catalyst design. However, due to the complicated electronic structures of metal oxides, the correlation of the binding energies of reaction intermediates (*OH, *O, and *OOH) in the oxygen evolution reaction (OER) with experimentally controllable properties of metal oxides has not been well established. Here we demonstrate that excess electrons are the essential factor that governs the binding properties of intermediates on the surfaces of reducible metal oxides. We propose that the number of excess electrons (NEE) is an essential activity descriptor toward the OER activities of these oxides, which perfectly reproduces the volcano curve plotted using the descriptor ΔGO – ΔGOH, so that tuning NEE can effectively tailor the OER activities of reducible metal oxide based catalysts. Guided by this descriptor, we predict a novel non-precious catalyst with an overpotential of 0.54 eV, which could be a potential alternative to current Ru or Ir based catalysts.

In order to synthesize the zinc-titanium (Zn-Ti) oxide nanocomposites using an atmospheric soft plasma jet, in this study mixtures of Zn and Ti precursors such as zinc nitrate and titanium butoxide were first prepared with different molar ratios; the mixed precursors then stirred at 700 rpm for two hours with atmospheric plasma, while maintaining a temperature of 25 °C. All the synthesized Zn-Ti oxide nanocomposites were post-heat-treated at 600 °C for six hours in an electrical furnace. The morphology, particle shape and size, crystal structure, oxidation state, and composition ratio were analyzed using FE-SEM, XRD, SEM-EDS, and Raman spectroscopy. BET was measured to calculate the specific surface area of the Zn-Ti oxide nanocomposites. Photocatalytic activity tests were performed for an application study, with 10 mL of 10 ppm methylene blue dye. UV-visible spectroscopy was performed on five different samples in order to analyze the changes of photocatalytic reactions. When the composition ratio of Zn/Ti was 2/1, maximum photocatalytic efficiency was obtained. We also carried out a theoretical kinetic study.

An important pathway for functionalization of porphyrin-based organic-inorganic structures is the metalation of porphyrins. Recently, the porphyrin metalation was demonstrated on different metal oxide surfaces, however, the underlying mechanisms regarding the role of the surface morphology, the substituted metal, and ligands are still under investigation. Here we address the adsorption and self-metalation of H2TPP on a MgO(001) surface with low-coordinated sites. We employ ab initio molecular dynamics simulations around room temperature to provide insight into dynamic steric effects. We observe that H2TPP is mobile on the pristine surface as the steric hindrance by phenyl rings prevents the physisorption of the macrocycle at a specific site. In contrast, step edges or kink sites provide anchor points exposing low-coordinated, reactive oxygen-sites to hydrogens of the macrocycle. We report a spontaneous proton transfer at these sites forming an intermediate complex before the metalation occurs. The energetics of the self-metalation reaction is modeled. Deutsche Forschungsgemeinschaft BO 1851/4-1 Fonds zur Förderung der Wissenschaftlichen Forschung (DE-588)2054142-9 I 3385-N34 Version of record

The electric response of a system formed by an electrolyte in contact with porous electrode is investigated. The simple case in which only the positive ions are mobile is considered. The first scenario is the one in which the mobile ions can be immobilized by means of an irreversible reaction. We show that the existing model, based on this assumption, is not suitable to describe in a proper manner the electric response of the cell to an external electric excitation, because in a one dimensional problem the electric current density, usually defined as the sum of the conduction and displacement currents, is not position independent. Consequently, it cannot be used to analyze the current-voltage characteristics, or the electrical impedance of the cell. A generalization of the model, in which the mobile ions are instead immobilized by a reversible reaction, allows the impedance of the cell to be determined in such a way to be meaningful for the investigations carried out with the impedance spectroscopy technique. Special attention is devoted to the problem of a cell limited by one blocking electrode and one transparent electrode, which corresponds to a porous electrode of immersed in an electrolytic solution. The model is subsequently generalized in such a way that the ionic diffusion is regulated by a time fractional equation to take into account the porous nature of the medium. In order to validate the theoretical model, we select a case of study that well represent the modeled system in which the working electrode is made up of lithium titanate () nanotubes in contact with an organic electrolyte. The theoretical predictions of the resulting model are in good agreement with the experimental data on the full frequency range explored.

Invention of novel nanomaterials guaranteeing enhanced biomedical performance in diagnostics and therapeutics, is a perpetual initiative. In this regard, the upsurge and widespread usage of nanoparticles is a ubiquitous phenomenon, focusing predominantly on the application of submicroscopic (< 100 nm) particles. While this is facilitated attributing to their wide range of benefits, a major challenge is to create and maintain a balance, by alleviating the associated toxicity levels. In this minireview, we collate and discuss particularly recent advancements in therapeutic applications of metal and metal oxide nanoparticles in skin and cosmetic applications. On the one hand, we outline the dermatological intrusions, including applications in wound healing. On the other hand, we keep track of the recent trends in the development of cosmeceuticals via nanoparticle engrossments. The dermato-cosmetic applications of metal and metal oxide nanoparticles encompass diverse aspects, including targeted, controlled drug release, and conferring ultraviolet and antimicrobial protections to the skin. Additionally, we deliberate on the critical aspects in comprehending the advantage of rheological assessments, while characterizing the nanoparticulate systems. As an illustration, we single out psoriasis, to capture and comment on the nanodermatology-based curative standpoints. Finally, we lay a broad outlook and examine the imminent prospects.

A temperature-programmed desorption (TPD) study of CO and NH₃ adsorption on MnO(100) with complimentary density functional theory (DFT) simulations was conducted. TPD reveals a primary CO desorption signal at 130 K from MnO(100) in the low coverage limit giving an adsorption energy of -35.6 ±2.1 kJ/mol on terrace sites. PBE+U gives a more reasonable structural result than PBE, and the adsorption energy obtained by PBE+U and DFT-D3 Becke-Johnson gives excellent agreement with the experimentally obtained ΔEads for adsorption at Mn²⁺ terrace sites. The analysis of NH₃-TPD traces revealed that adsorption energy on MnO(100) is coverage-dependent. At the low-coverage limit, the adsorption energy on terraces is -58.7±1.0 kJ/mol. A doser results in the formation of a transient NH₃ multilayers that appears in TPD at around 110K. For a terrace site, PBE+U predicts a more realistic surface adsorbate geometry than PBE does, with PBE+U with Tkatchenko-Scheffler method with iterative Hirshfeld partitioning (TSHP) provides the best prediction. DFT simulations of the dehydrogenation elementary step of the ethyl and methyl fragments on α-Cr2O₃(101̅2) were also conducted to complement previous TPD studies of these subjects. On the nearly-stoichiometric surface of α-Cr₂O₃(101̅2), CD₃₋ undergoes dehydrogenation to produce CD₂=CD₂ and CD₄. Previous TPD traces suggest that the α-hydrogen (α-H) elimination of methyl groups on α-Cr₂O₃(101̅2) is the rate-limiting step, and has an activation barrier of 135±2 kJ/mol. DFT simulations showed that PBE gives reasonable prediction of the adsorption sites for CH3- fragments in accordance with XPS spectra, while PBE+U did not. Both PBE and PBE+U failed to predict the correct adsorption sites for CH₂=. When the simulation is set in accordance with the experimentally observed adsorption sites for the carbon species, PBE gives very accurate prediction on the reaction barrier when an adjacent I adatom is present, while PBE+U failed spectacularly. When the simulation is set in accordance with the DFT-predicted adsorption sites, PBE is still able to accurately predict the reaction barrier (

Oxide aerogels are pore–solid networks notable for their low density, large pore volume, and high surface area. This three-dimensional arrangement of pore and solid provides critical properties: the high surface area required to maximize the number of active sites and a through-connected porosity that plumbs reactants to the active interior. In decontamination applications where reactivity beyond adsorption is desired to degrade deleterious molecules, oxide aerogels offer multiple avenues to add oxidative power to this unique arrangement of pore and solid. For protection against chemical warfare agents or toxic industrial chemicals, metal-oxide aerogels with their oxide/hydroxide surfaces afford stability under ambient conditions against competing sorbents such as water and oxygen. In this review, strategies to maximize sorptive capacity and degradation rate by modifying surface functionality, compositing with dissimilar oxides, or adding metallic nanoparticles and the subsequent impact on decontamination performance will be summarized and expected directions for future research will be discussed based on the observed trends.