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Si-Ge interdiffusion with phosphorus doping was investigated by both experiments and modeling. Ge/Si1-xGex/Ge multi-layer structures with 0:75 < xGe < 1, a mid-1018 to low-1019 cm-3 P doping, and a dislocation density of 108 to 109 cm-2 range were studied. The P-doped sample shows an accelerated Si-Ge interdiffusivity, which is 2-8 times of that of the undoped sample. The doping dependence of the Si-Ge interdiffusion was modelled by a Fermi-enhancement factor. The results show that the Si-Ge interdiffusion coefficient is proportional to n²=n²i for the conditions studied, which indicates that the interdiffusion in a high Ge fraction range with n-type doping is dominated by V2- defects. The Fermi-enhancement factor was shown to have a relatively weak dependence on the temperature and the Ge fraction. The results are relevant to the structure and thermal processing condition design of n-type doped Ge/Si and Ge/SiGe based devices such as Ge/Si lasers. [ABSTRACT FROM AUTHOR]

Extending the stability of polymeric membranes in organic solvents is important for applications in chemical and pharmaceutical industry. Thin-film composite membranes with enhanced solvent permeance are proposed, using porphyrin as a building block. Hybrid polyamide films are formed by interfacial polymerization of 5,10,15,20-(tetra-4-aminophenyl)porphyrin/m-phenylene diamine (MPD) mixtures with trimesoyl chloride. Porphyrin is a non-planar molecule, containing a heterocyclic tetrapyrrole unit. Its incorporation into a polyamide film leads to higher free volume than that of a standard polyamide film. Polyamide films derived from porphyrin and MPD amines with a fixed total amine concentration of 1 wt% and various porphyrin/MPD ratios were fabricated and characterized. The porphyrin/MPD polyamide film was complexed with Cu(II), due to the binding capacity of porphyrin to metal ions. By coupling scanning transmission electron microscopy (STEM) with electron energy-loss spectroscopy (EELS), Cu mapping was obtained, revealing the distribution of porphyrin in the interfacial polymerized layer. By using porphyrin as amine-functionalized monomer a membrane with thin selective skin and enhanced solvent transport is obtained, with good dye selectivity in the nanofiltration range. For instance, an ultra-fast hexane permeance, 40-fold increased, was confirmed when using 0.5/0.5 porphyrin/MPD mixtures, instead of only MPD as amine monomer. A rejection of 94.2% Brilliant Blue R (826 g/mol) in methanol was measured. [ABSTRACT FROM AUTHOR]

Transmission electron microcopy (TEM) analysis of liquid metals, especially mercury (Hg), is difficult to carry out because their specimen preparation poses a daunting task due to the unique surface properties of these metals. This paper reports a cryoTEM study on Hg using a novel specimen preparation technique. Hg metal is mixed with water using sonication and quenched in liquid ethane cryogen. This technique permits research into the morphological, phase and structural properties of Hg at nanoscale dimensions. [ABSTRACT FROM AUTHOR]

Conductive polymer poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) exhibits a tunable conductivity ranging from 0.1 to 4380 S·cm-1 under different doping and/or dedoping strategies. However, the dependence of macroscopic electrical properties on the evolution of the microstructure is not clearly understood. This is the first study that systematically investigated the spatial arrangement of the ordered and disordered phases in PEDOT/PSS nanofilms by bright-field (BF), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) combined with electron energy loss spectroscopy (EELS) and element-thickness mapping. Our observations clarify how amorphous PSS hinders electrical transport at various length scales in the PEDOT/PSS films. Moreover, the mechanism for an enhancement in 3 orders of magnitude in electrical conductivity was proved by TEM investigation, which is mainly due to a more uniform dispersion by dedoping that opens PEDOT nanoparticle clusters in PEDOT/PSS films. Our microstructural and electrical studies show that the change in spatial arrangement and interaction of small PEDOT domains plays a considerable role in the final electron transport. [ABSTRACT FROM AUTHOR]

The challenge in the electrochemical reduction of aqueous carbon dioxide is in designing a highly selective, energy-efficient, and non-precious-metal electrocatalyst that minimizes the competitive reduction of proton to form hydrogen during aqueous CO2 conversion. A non-noble metal electrocatalyst based on a copper-indium (Cu-In) alloy that selectively converts CO2 to CO with a low overpotential is reported. The electrochemical deposition of In on rough Cu surfaces led to Cu-In alloy surfaces. DFT calculations showed that the In preferentially located on the edge sites rather than on the corner or flat sites and that the d-electron nature of Cu remained almost intact, but adsorption properties of neighboring Cu was perturbed by the presence of In. This preparation of non-noble metal alloy electrodes for the reduction of CO2 provides guidelines for further improving electrocatalysis. [ABSTRACT FROM AUTHOR]

A new dry reforming of methane catalyst comprised of NiCo bimetallic nanoparticles and a Mg x(Al)O support that exhibits high coke resistance and long-term on-stream stability is reported. The structural characterization by XRD, TEM, temperature-programmed reduction, and BET analysis demonstrates that the excellent performance of this catalyst is ascribed to the synergy of various parameters, including metal-nanoparticle size, metal-support interaction, catalyst structure, ensemble size, and alloy effects. [ABSTRACT FROM AUTHOR]

Ultrafine TaO x nanoparticles were electrodeposited on carbon black (CB) powder in a nonaqueous Ta complex solution at room temperature, and the resultant TaO x /CB catalysts were assessed as oxygen reduction reaction (ORR) electrocatalysts for polymer electrolyte fuel cell (PEFC) cathodes. The Ta electrodeposition process was scaled up using a newly designed working electrode containing a CB dense layer, without introducing any binder such as the ionomer Nafion in the electrode for electrodeposition. The electrodeposited TaO x /CB powders were removed from the deposition electrode and subsequent H 2 treatment at varying temperatures between 523 and 1073 K was attempted to increase the ORR performance. The TaO x /CB samples were characterized by SEM, STEM, XPS, and EELS measurements. XPS and EELS results indicated the reduced nature of the Ta species caused by the high-temperature treatment in H 2 , while STEM images clearly revealed that the TaO x particles aggregated as the treatment temperature increased. When the TaO x /CB catalyst, which was treated at 873 K for 2 h, was deposited on a glassy carbon substrate with Nafion ionomer, it resulted in the highest activity among the samples investigated, giving an onset potential of 0.95 V RHE at -2 μA cm −2 in a 0.1 M H 2 SO 4 solution. Moreover, the long-term stability test with 10,000 cycles of the voltammetry only led to a 6% loss in the ORR currents, demonstrating the high stability of the TaO x /CB catalysts. Kinetic analysis by R(R)DE indicated that the four-electron transfer pathway in the ORR process was dominant for this TaO x /CB catalyst, and Tafel plots showed a slope corresponding to a one-electron reaction for the rate-determining step. [ABSTRACT FROM AUTHOR]

A new one pot, surfactant-free, synthetic route based on the surface organometallic chemistry (SOMC) concept has been developed for the synthesis of Sn surface-enriched Pt–Sn nanoparticles. Bu 3 SnH selectively reacts with [Pt]–H formed in situ at the surface of Pt nanoparticles, Pt NPs, obtained by reduction of K 2 PtCl 4 by LiB(C 2 H 5 ) 3 H. Chemical analysis, 1 H MAS and 13 C CP/MAS solid-state NMR as well as two-dimensional double-quantum (DQ) and triple-quantum (TQ) experiments show that organo-tin moieties Sn(n-C 4 H 9 ) are chemically linked to the surface of Pt NPs to produce, in fine, after removal of most of the n-butyl fragment, bimetallic Pt–Sn nanoparticles. The Sn(n-CH 2 CH 2 CH 2 CH 3 ) groups remaining at the surface are believed to stabilize the as-synthesized Pt–Sn NPs, enabling the bimetallic NPs to be well dispersed in THF. Additionally, the Pt–Sn nanoparticles can be supported on MgAl 2 O 4 during the synthesis of the nanoparticles. Some of the Pt–Sn/MgAl 2 O 4 catalyst thus prepared exhibits high activity in PROX of CO and an extremely high selectivity and stability in propane dehydrogenation to propylene. The enhanced activity in propane dehydrogenation is associated with the high concentration of inactive Sn at the surface of Pt nanoparticles which “isolates” the active Pt atoms. This conclusion is confirmed by XRD, NMR, TEM, and XPS analysis. [ABSTRACT FROM AUTHOR]

Abstract: TiO2 nanoparticles (NPs) were prepared using flame synthesis and then characterized using transmission electron microscopy. We found that the flame method yields both crystalline TiO2 and amorphous TiO2 NPs. TEM analysis revealed that only the crystalline TiO2 NPs were coated with carbon. Based on this observation, we proposed a growth model for the diffusion and precipitation of carbon atoms in TiO2 NPs. The optical properties of TiO2 NPs were investigated by performing valence electron energy loss spectrometry analysis. We observed that carbon-coated TiO2 NPs have higher absorption in the visible range due to their lower band-gap energy. [Copyright &y& Elsevier]

Abstract: A multi-element diffusion flame burner (MEDB) is useful in the study of flame synthesis of nanomaterials. Here, the growth of pure anatase and carbon-coated titanium dioxide (TiO2) using an MEDB is demonstrated. Hydrogen (H2), oxygen (O2), and argon (Ar) are utilized to establish the flame, whereas titanium tetraisopropoxide is used as the precursor for TiO2. The nanoparticles are characterized using high-resolution transmission electron microscopy, with elemental mapping (of C, O, and Ti), X-ray diffraction, Raman spectroscopy, and thermogravimetric analysis. The growth of pure anatase TiO2 nanoparticles occurs when Ar and H2 are used as the precursor carrier gas, while the growth of carbon-coated nanoparticles ensues when Ar and ethylene (C2H4) are used as the precursor carrier gas. A uniform coating of 3–5nm of carbon is observed around TiO2 particles. The growth of highly crystalline TiO2 nanoparticles is dependent on the gas flow rate of the precursor carrier and amorphous particles are observed at high flow rates. Carbon coating occurs only on crystalline nanoparticles, suggesting a possible growth mechanism of carbon-coated TiO2 nanoparticles. [Copyright &y& Elsevier]

Produced water (PW) and formation water are complex mixtures of hydrocarbons and water produced at oil and gas upstream facilities. Submicron oil droplets represent a multitude of issues affecting the performance of downstream advanced water treatment processes, such as micro and ultra-filtration processes. Conventional de-oiling technologies do not efficiently remove submicron oil droplets in PW. An accurate characterization of submicron oil droplets and contaminants is required to improve PW treatment technology. In this study, a methodology for visualization and quantification of submicron oil droplets size distribution (DSD), using optical and electron microscopy techniques, was developed. Various microscopy techniques were evaluated, including epifluorescence microscopy (EpiFM), confocal laser scanning microscopy (CLSM), cryogenic scanning and transmission electron microscopy (cryo-SEM and cryo-TEM, respectively). Synthetic PW was used to improve and standardize the sample preparation and characterization methodology. The improved methodology was then tested with two PW samples from different oilfields in the Middle East region. Two methods were developed for the determination of DSD in oilfield PW samples. The first method is suitable for highly polydisperse PW samples with oil droplets larger than 250 nm. This method is based on using low-temperature agarose to immobilize the samples, avoiding coalescence, and allowing clear visualization of the oil droplets at high magnification in EpiFM. The second method is suitable for concentrated PW samples and oil droplets as small as 20 nm in size. This method is based on cryo-TEM with plunge freezing and without the use of agarose for sample immobilization. The agarose-immobilization technique was also applied for sample preparation in cryo-SEM. Cryo-SEM fixation by high-pressure freezing (HPF) preserved the morphology of oil droplets in synthetic oil-concentrated samples and allowed its visualization in a wide range of sizes from 50 nm up to 20 μm. Cryo-TEM imaging of oilfield PW samples revealed the presence of oil droplets as small as 20 nm in size. However, no quantification of the DSD in the oilfield PW samples was possible due to the low oil concentration. Moreover, a relatively large amount of other submicron particulates/aggregates were observed in PW samples. Cryo-SEM coupled with energy-dispersive X-ray spectroscopy (EDS) provided valuable information on the morphology and elemental composition of the submicron-sized contaminants. These submicron contaminants would not be removed by conventional de-oiling technologies and might cause intrapore blocking in membrane filtration systems downstream. The effect of these submicron contaminants, other than oil droplets present in PW, needs to be addressed to improve the PW treatment technologies. [Display omitted] • A new method based on EpiFM of immobilized gelled samples is proposed to determine the DSD. • Oil droplets as small as 20 nm were observed in oilfield PW samples by cryo-TEM. • Cryo-SEM-EDS complements information on the nature of the submicron contaminants in PW. • Submicron contaminants other than oil droplets should be further studied for improved PW treatment. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the effect of electron beam irradiation on the dielectric properties of As2S3 chalcogenide glass. By means of low-loss electron energy loss spectroscopy, we derive the permittivity function, its dispersive relation, and calculate the refractive index and absorption coefficients under the constant permeability approximation. The measured and calculated results show a heretofore unseen phenomenon: a reduction in the permittivity of ≥40%. Consequently a reduction of the refractive index of 20%, hence, suggests a conspicuous change in the optical properties of the material under irradiation with a 300 keV electron beam. The plausible physical phenomena leading to these observations are discussed in terms of the homopolar and heteropolar bond dynamics under high energy absorption. The reported phenomena, exhibited by As2S3-thin film, can be crucial for the development of photonics integrated circuits using electron beam irradiation method. [ABSTRACT FROM AUTHOR]

Complex systems are prevalent in various disciplines encompassing the natural and social sciences, such as physics, biology, economics, and sociology. Leveraging data science techniques, particularly those rooted in artificial intelligence and machine learning, offers a promising avenue for comprehending the intricacies of complex systems without necessitating detailed knowledge of underlying dynamics. In this paper, we demonstrate that multiscale entropy (MSE) is pivotal in describing the steady state of complex systems. Introducing the multiscale entropy dynamics (MED) methodology, we provide a framework for dissecting system dynamics and uncovering the driving forces behind their evolution. Our investigation reveals that the MED methodology facilitates the expression of complex system dynamics through a Generalized Nonlinear Schrödinger Equation (GNSE) that thus demonstrates its potential applicability across diverse complex systems. By elucidating the entropic underpinnings of complexity, our study paves the way for a deeper understanding of dynamic phenomena. It offers insights into the behavior of complex systems across various domains. [ABSTRACT FROM AUTHOR]

This work presents a hydrothermal-based facile method for synthesizing ZnFe2O4, whose size can be controlled with the concentration of sodium acetate used as a fuel and its physical changes at nanoscales when exposed to two different gases. The structural, morphological, compositional, and electronic properties of the synthesized samples are also presented in this paper. The crystal structure of the synthesized samples was determined using an X-ray Diffractometer (XRD). The results revealed fluctuations in the size, lattice parameter, and strain in the nanoparticles with increasing the concentration of sodium acetate. Field-Emission Scanning Electron Microscopy (FESEM) was used to determine synthesized materials' morphology and particle size. It revealed that the particles possessed approximately spherical morphology whose size decreased significantly with the increasing amount of sodium acetate. Transmission Electron Microscopy (TEM) was utilized to determine the structure, morphology, and elemental distributions in particles at the nanoscale, and it confirmed the findings of XRD and FESEM analyses. The high-resolution TEM (HRTEM) imaging analysis of the nanoparticles in our studied samples revealed that the particles predominantly possessed (001) type facets. X-ray photoelectron spectroscopy (XPS) and core-loss electron energy loss spectroscopy (EELS) showed an increasing fraction of Fe2+ with the decreasing size of the particles in samples. The Brunauer, Emmett, and Tellers (BET) analysis of samples revealed a higher surface area as the particle size decreases. In addition, the determined surface area and pore size values are compared with the literature, and it was found that the synthesized materials are promising for gas-sensing applications. The ab initio calculations of the Density of States (DOS) and Band structure of (001) surface terminating ZnFe2O4 were carried out using Quantum Espresso software to determine the bandgap of the synthesized samples. They were compared to their corresponding experimentally determined bandgap values and showed close agreement. Finally, in-situ TEM measurement was carried out on one of the four studied samples with robust properties using Ar and CO2 as reference and target gases, respectively. It is concluded from the presented study that the size reduction of the ZnFe2O4 nanoparticles (NPs) tunes the bandgap and provides more active sites due to a higher concentration of oxygen vacancies. The in-situ TEM showed us a nanoscale observation of the change in one of the crystal structure parameters. The d spacing of ZnFe2O4 NPs showed a noticeable fluctuation, reaching more than 5% upon exposure to CO2 and Ar gases. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel approach of fabrication of a DNA sensor has been proposed. • Proposed composite to be used as biosensor has been fabricated using simple technique. • Efficiency dependence of Au/Ng/SWCNTs Modified Electrode on SWCNTs concentration has been observed. • FTO substrate was used instead of glassy carbon to achieve cost effective sensor. • DNA detection and sensitivity of biosensor was proved to be good. An easy, quick, and efficient detection of Multidrug Resistance (MDR) of cancer cells at the clinical level is the need of the hour for the effective treatment of leukemia patients. In this study, we reported carbon nanomaterials-based biosensors based on Au nanoparticles (Au-NPs) decorated on Nitrogen-doped Graphene (NG) and Single-Walled Carbon Nanotubes (SWCNTs) for effective, efficient, and sensitive detection of affected DNA. Three Au/NG/SWCNT-based Modified Electrode (ME) were made containing 2, 4, and 6 mg SWCNTs. The thiol group attached at the 5′end was immobilized at ME due to a strong bond between the Au-NPs and thiol group. NG/SWCNTs enhanced the performance of the composite due to its better sensitivity and fast electron transport. Electrochemical Impedance Spectroscopy (EIS), Cyclic Voltammetry (CV), and Differential Potential Voltammetry (DPV) analysis were performed to monitor the performance of the sensor after the hybridization of target DNA onto the capture probe on the modified electrode surface. Different target DNA sequences were used to check the selectivity and sensitivity of the fabricated biosensor. The selectivity performance of prepared DNA sensors was also proved to be good shown by DPV results. The findings of this study provide insights for developing new highly sensitive, selective, and cost-effective portable biosensors for MDR gene detection, which will enable the early diagnosis of cancer more effective at the clinical level. Compared with previous DNA sensors with oligonucleotides directly incorporated on carbon electrodes, this carbon nanotube-based assay with its large surface area and good charge-transport characteristics dramatically increased DNA attachment quantity and complementary DNA detection sensitivity. [ABSTRACT FROM AUTHOR]

Quaternary CuGa2In3S8 photocatalysts with a primary particle size of 4 nm are prepared by using a solution of Cu(acac)2, Ga(acac)3, In(acac)3, trioctylphosphine oxide, and oleylamine to which 1-dodecanethiol is injected under Ar atmosphere (150 °C, aging at 285 °C for 2-24 h). [ABSTRACT FROM AUTHOR]

The article presents the author's views on the role of MXene in the performance of hydrogels in strain sensors. Various topics discussed include calculation of asymmetrical strain sensitivity, viscoelastic property of hydrogels, its benefits, hydrogel sensors in selectivity and sensitivity in gauge factor (GF).

Several systems have shown the ability to stabilize uncommon crystal structures during the synthesis of metallic nanoparticles. By tailoring the nanoparticle crystal structure, the physical and chemical properties of the particles can also be controlled. Herein, we synthesized branched nanoparticles of mixed fcc/hcp ruthenium, which were formed using tungsten carbonyl [W(CO)6] as both a reducing agent and a source of carbon monoxide. The branched particles were formed from multiple particulates off a central core. High-resolution transmission electron microscopy (HRTEM) clearly showed that the branched structures consisted of aligned hcp crystal domains, a mixture of fcc and hcp crystal domains with several defects and misalignments, and particles that contained multiple cores and branches. Branched particles were also formed with molybdenum carbonyl [Mo(CO)6], and faceted particles of hcp and fcc were formed with rhenium carbonyl [Re2(CO)10] as a carbon monoxide source. Without metal carbonyls, small particles of spherical hcp ruthenium were produced, and their size could be controlled by the selection of the precursor. The ruthenium nanoparticles were tested for ammonia borane hydrolysis; the branched nanoparticles were more reactive for catalytic hydrogen evolution than the faceted fcc/hcp nanoparticles or the spherical hcp nanoparticles. This work showcases the potential of crystal phase engineering of transition metal nanoparticles by different carbon monoxide precursors for tailoring their catalytic reactivity. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis of metal sulfide (MS) materials with sizes in the sub‐10 nm regime often requires capping agents with long hydrocarbon chains that affect their structures and properties. Herein, this study presents a molten‐state synthesis method for a series of transition‐MS nanoparticles using thiourea as a reactive precursor without capping agents. This study also reports the synthesis of MS with single metals (Fe, Co, Ni, Cu, and Zn) and quaternary CuGa2In3S8 using the same synthesis protocol. Thiourea first melts to form a molten‐state condition to serve as the reaction medium at a relatively low temperature (<200 °C), followed by its thermal decomposition to induce a reaction with the metal precursor to form different MS. This synthesis protocol, owing to its dynamic characteristics, involves the formation of a variety of organic carbon nitride polymeric complexes around the MS particles. Dynamic nuclear polarization surface‐enhanced nuclear magnetic resonance spectroscopy is effective to identify the polymeric compositions and structures as well as their interactions with the MS. These results provided thorough structural descriptions of the MS nanoparticles surrounded by the carbon nitride species derived from thiourea, which may find various applications, including photocatalytic water splitting. [ABSTRACT FROM AUTHOR]

Natural or synthetic graphite as precursors for the preparation of graphene oxide (GO) have constraints due to their limited availability, high reaction temperature for processing of synthetic graphite and higher generation cost. The use of oxidants, long reaction duration, the generation of toxic gases and residues of inorganic salts, the degree of hazard and low yield are some of the disadvantages of the oxidative-exfoliation methods. Under these circumstances, biomass waste usage as a precursor is a viable alternative. The conversion of biomass into GO by the pyrolysis method is ecofriendly with diverse applications, which partially overcomes the waste disposal problem encountered by the existing methods. In this study, graphene oxide (GO) is prepared from dry leaves of sugarcane plant through a two-step pyrolysis method using ferric (III) citrate as a catalyst, followed by treatment with conc. H2SO4. The synthesized GO is analyzed by UV-Vis., FTIR, XRD, SEM, TEM, EDS and Raman spectroscopy. The synthesized GO has many oxygen-containing functional groups (–OH, C–OH, COOH, C–O). It shows a sheet-like structure with a crystalline size of 10.08 nm. The GO has a graphitic structure due to the Raman shift of G (1339 cm−1) and D (1591 cm−1) bands. The prepared GO has multilayers due to the ratio of 0.92 between ID and IG. The weight ratios between carbon and oxygen are examined by SEM-EDS and TEM-EDS and found to be 3.35 and 38.11. This study reveals that the conversion of sugarcane dry leaves into the high-value-added material GO becomes realistic and feasible and thus reduces the production cost of GO. [ABSTRACT FROM AUTHOR]

Efficient water splitting requires highly active, earth-abundant, and robust catalysts. Monometallic phosphides such as Ni2P have been shown to be active toward water splitting. Our theoretical analysis has suggested that their performance can be further enhanced by substitution with extrinsic metals, though very little work has been conducted in this area. Here we present for the first time a novel PH3 plasma-assisted approach to convert NiCo hydroxides into ternary NiCoP. The obtained NiCoP nanostructure supported on Ni foam shows superior catalytic activity toward the hydrogen evolution reaction (HER) with a low overpotential of 32 mV at -10 mA cm-2 in alkaline media. Moreover, it is also capable of catalyzing the oxygen evolution reaction (OER) with high efficiency though the real active sites are surface oxides in situ formed during the catalysis. Specifically, a current density of 10 mA cm-2 is achieved at overpotential of 280 mV. These overpotentials are among the best reported values for non-noble metal catalysts. Most importantly, when used as both the cathode and anode for overall water splitting, a current density of 10 mA cm-2 is achieved at a cell voltage as low as 1.58 V, making NiCoP among the most efficient earth-abundant catalysts for water splitting. Moreover, our new synthetic approach can serve as a versatile route to synthesize various bimetallic or even more complex phosphides for various applications. [ABSTRACT FROM AUTHOR]

• We study the effect of Si/Al ratio in Zeolite-Y on heptane hydrocracking • The effect of bi-metallicity (Ni-W) was also examined. • Bimetallicity resulted in enhanced metal dispersion and larger BET surface area. • Ni-W/Zeolite-Y catalysts were more catalytically active than Ni/Zeolite-Y. • Hydrocracking over Zeolites with high Si/Al ratio was more stable with time. This study investigated the effect of the SiO 2 /Al 2 O 3 ratio in the range of 5-80 in zeolite Y (ZY) as a support for the bi-functional reaction of heptane hydrocracking. Bi-metallicity impact, through the addition of W on Ni in the supported metal catalysts was also examined. The catalytic activity was assessed at 350°C and 400°C in order to deduce an optimized composition of the catalyst in terms of metal composition and Si/Al ratio. The results were correlated to the catalysts' surface and bulk properties, the latter after employing a number of material characterization techniques. It was shown that Ni-W bimetallic catalysts demonstrated better catalytic activity (conversion, 78% to 91%) than Ni-based monometallic counterpart catalysts (conversion, 74.2% to 82.7%), with NiO-WO 3 -ZY30 (SiO 2 /Al 2 O 3 ratio equal to 30) exhibiting the highest conversion. This was attributed to the bimetallic's enhanced metal dispersion and smaller particle size, evaluated using temperature-programmed desorption (TPD) of H 2 and high-resolution transmission electron microscopy (HR-TEM) imaging. The stronger acidity, as quantified by total acidity calculations, of zeolite Y having higher Si/Al ratio, and their balanced ratio of micro- and meso-porosity played a vital role in their catalytic performance. This study provides useful design guidelines on how to adjust both the Si/Al ratio in the zeolite Y support and the catalyst's bimetallicity for enhanced hydrocracking performance. [Display omitted] [ABSTRACT FROM AUTHOR]

The “wet” sol–gel and “dry” solid-state methods were used to prepare Ni–Ta–O mixed oxide catalysts. The resulting Ni–Ta oxides exhibit high activity and selectivity for the low temperature oxidative dehydrogenation of ethane to ethylene. The Ta/(Ni + Ta) atomic ratios (varying from 0 to 0.11 in “wet” sol–gel method, and from 0 to 0.20 in “dry” solid-state method) as well as the preparation methods used in the synthesis, play important roles in controlling catalyst structure, activity, selectivity and stability in the oxidative dehydrogenation of ethane. Electron microscopy characterizations (TEM, EELS mapping, and HAADF-STEM) clearly demonstrate that the Ta atoms are inserted into NiO crystal lattice, resulting in the formation of a new Ni–Ta oxide solid solution. More Ta atoms are found to be located at the lattice sites of crystal surface in sol–gel catalyst. While, a small amount of thin layer of Ta 2 O 5 clusters are detected in solid-state catalyst. Further characterization by XRD, N 2 adsorption, SEM, H 2 -TPR, XPS, and Raman techniques reveal different properties of these two Ni–Ta oxides. Due to the different properties of the Ni–Ta oxide catalysts prepared by two distinct approaches, they exhibit different catalytic behaviors in the ethane oxidative dehydrogenation reaction at low temperature. Thus, the catalytic performance of Ni–Ta–O mixed oxide catalysts can be systematically modified and tuned by selecting a suitable synthesis method, and then varying the Ta content. [ABSTRACT FROM AUTHOR]

• An easy approach to prepare plan-view TEM sample using FIB lift-out approach. • Plan view study of layered 2D materials. • HRTEM and SADP of misfit compound SnTiS 3 (SnS-TiS 2). • Plan-view imaging of vertically grown MoS 2 and graphene sheets (3D graphene). Plan-view transmission electron microscopy (TEM) or electron diffraction imaging of a bulk or 2D material can provide detailed information about the structural or atomic arrangement in the material. A systematic and easily implementable approach to preparing site-specific plan-view TEM samples for 2D thin film materials using FIB is discussed that could be routinely used. The methodology has been successfully applied to prepare samples from 2D materials such as, MoS 2 thin film, vertically oriented graphene film (VG), as well as heterostructure material SnTiS 3. It is worth mentioning that in contrast to planar conventional graphene, VG grows vertically from the substrate and takes nanosheet arrays. Samples prepared using this methodology provide a simple, faster, and precise course in obtaining valuable structural information. The top-view imaging offers various information about the growth nature of the materials suggesting the efficiency of the sample preparation process. [ABSTRACT FROM AUTHOR]

The construction of photocatalytic systems that have strong redox capability, effective charge separation, and large reactive surfaces is of great scientific and practical interest. Herein, an edge‐connected 2D/2D Z‐scheme system that combines the facet junction and the interfacial heterojunction to achieve effective long‐range charge separation and large reactive surface exposure is designed and fabricated. The heterostructure is realized by the selective growth of 2D‐layered MoS2 nanoflakes on the edge‐sites of thin TiO2 nanosheets via an Au‐promoted photodeposition method. Attributed to the synergetic coupling of the facet junction and the interfacial heterojunction that assures the effective charge separation, and the tremendous but physically separated reactive sites offered by layered MoS2 and highly‐exposed (001) facets of TiO2, respectively, the artificial Z‐scheme exhibits excellent photocatalytic performance in photodegradation tests. Moreover, the junctional plasmonic Au nanoclusters not only act as electron traps to promote the edge‐selective synthesis but also generate "hot electrons" to further boost photocatalytic performance. The Z‐scheme charge‐flow direction in the heterostructure and the roles of electrons and holes are comprehensively studied using in situ irradiated X‐ray photoelectron spectroscopy and photodegradation tests. This work offers a new insight into designing high‐performance Z‐scheme photocatalytic systems. [ABSTRACT FROM AUTHOR]

This study demonstrated the deposition of size-controlled gold (Au) nanoclusters via direct-current magnetron sputtering and inert gas condensation techniques. The impact of different source parameters, namely, sputtering discharge power, inert gas flow rate, and aggregation length on Au nanoclusters' size and yield was investigated. Au nanoclusters' size and size uniformity were confirmed via transmission electron microscopy. In general, Au nanoclusters' average diameter increased by increasing all source parameters, producing monodispersed nanoclusters of an average size range of 1.7 ± 0.1 nm to 9.1 ± 0.1 nm. Among all source parameters, inert gas flow rate exhibited a strong impact on nanoclusters' average size, while sputtering discharge power showed great influence on Au nanoclusters' yield. Results suggest that Au nanoclusters nucleate via a three-body collision mechanism and grow through a two-body collision mechanism, wherein the nanocluster embryos grow in size due to atomic condensation. Ultimately, the usefulness of the produced Au nanoclusters as catalysts for a vapor–liquid–solid technique was put to test to synthesize the phase change material germanium telluride nanowires. [ABSTRACT FROM AUTHOR]

We describe the sol–gel synthesisof the two new chalcogelsKFeSbS3and NaFeAsS3, which demonstrate excellentadsorption selectivity for volatile hydrocarbons and gases. Thesepredominantly mesoporous materials have been synthesized by reactingFe(OAc)2with K3SbS3or Na3AsS3in a formamide/water mixture at room temperature.Aerogels obtained after supercritical drying have BET surface areasof 636 m2/g and 505 m2/g for KFeSbS3and NaFeAsS3, respectively, with pore sizes in the micro-(below 2 nm), meso- (2–50 nm), and macro- (above 50 nm) regions. [ABSTRACT FROM AUTHOR]

• A novel method for diesel fuel formulation is studied through aromatics oxygenation. • Diesel surrogate is modified by replacing a portion of aromatics with oxygenated ones. • A reduction in threshold soot index with negligible effect on cetane number is observed. • Soot is collected from flames of diesel surrogate and fuels with benzyl alcohol and anisole. • Soots from oxygenated fuels exhibited lower crystallite lengths and higher reactivity. To address the rising demand for cost-effective and eco-friendly transportation fuels, the blending of fossil fuels with oxygenated biofuels presents a promising solution to reduce our dependence on fossil fuels as well the emission of pollutants such as CO, soot, and NOx. However, biofuels have limited availability and are generally expensive to produce. To achieve low pollutant emissions due to the existence of fuel-bound oxygen, in this study, a portion of sooting aromatics existing in diesel is replaced with oxygenated-aromatics to validate if a clean fuel formulation strategy, where a hydrocarbon stream in a refinery rich in aromatics is catalytically oxygenated to obtain oxygenated aromatics before blending it with other hydrocarbons to produce diesel, could be beneficial. For reproducibility, a diesel surrogate fuel containing n -decane, n -hexadecane, and toluene was formulated that had properties such as molecular weight, density, threshold sooting index, and cetane index similar to that of commercial diesel. In line with the above fuel formulation strategy, a portion of aromatics (toluene) in diesel surrogate fuel is changed with oxygenated aromatics, benzyl alcohol and anisole that have structural similarity with toluene. The threshold sooting indices of the diesel surrogate and the oxygenated fuel blends indicate reduced sooting propensity of the latter in comparison to the former fuel. The characterization of soot particles, produced from the combustion of diesel surrogate and oxygenated blends, using TGA, XRD, HRTEM, and EDS elemental analysis indicates higher soot reactivity with smaller particle and crystallite sizes with oxygenated blends. Thus, the fuel formulation strategy discussed in this study can decrease diesel soot emission by hampering soot growth and accelerating oxidation and can enhance soot reactivity to diminish its lifespan in the environment. [ABSTRACT FROM AUTHOR]

The interactions of Iridium (Ir) noble metal atoms/clusters (Ir NMAs/NMCs) with graphene are investigated due to their remarkable catalytic performance, resulting from the use of 100 % metal atoms compared to nanoparticle counterparts. Using scanning transmission electron microscopy (STEM), various forms of Ir dispersed on graphene were observed, including single atoms, dimers, and trimers clusters. The STEM data further revealed inter-atomic distances of 2.83 Å and 2.96 Å for dimers and trimers which were 20 % and 17 % larger than the numbers found through density functional theory (DFT) calculations. The DFT calculations further showed that the Dirac-cone of graphene at Ir NMAs/NMCs locations changes to metallic form due to the emergence of energy states at the Fermi level. This effect results in non-zero effective masses of charge carriers but enhances their density of states (DOS) by 2-fold which is believed to increase the energy absorption efficiency of graphene in the infra-red range of radiation. [Display omitted] • Understanding Ir NMCs' interactions with graphene through theory and experiment. • Reporting of a change in the local density of states of graphene in the presence of Ir NMCs. • Measuring interatomic distances between Ir metal dimers and trimer through experiment and their comparison with theory. [ABSTRACT FROM AUTHOR]

MOFs derived supported catalysts showing strong metal-support interactions along with stable and high catalytic activity towards methane dry reforming. [Display omitted] • One-pot supported Ni catalysts with SMSI are designed by tuning the pyrolysis of MOFs. • Pyrolysis impacts the microstructure, composition, and interface of the derived catalysts. • Coalesced MOFs derived catalyst show high and stable activity for methane dry reforming. • Operando studies revealed the lattice oxygen mobility and carbon pathways under DRM conditions. • Minimal coking and sintering under elevated DRM conditions evidence the robustness of the catalysts. Dry reforming of methane (DRM) is an inimitable approach for eliminating both greenhouse gases, methane and CO 2 , while producing synthesis gas which further can be converted to added-value fuels. However, the industrialization of DRM has been limited due to sintering and coking to the catalysts under the harsh reaction conditions. Here, we propose a new methodology for producing tunable supported nickel-based catalysts for DRM using metal organic frameworks (MOFs) as precursors of the catalyst components. In particular, Ni- and La-MOFs were coalesced using sonication and then calcined at different temperatures to produce catalysts with tailored Ni metal size (5–20 nm) and tuned strong metal-support interactions (SMSI). Here, the synthesis of nickel and nickel oxide nanoparticles embedded on lanthanum-based supports by controlled calcination of the MOF structures is demonstrated; the Ni supported catalysts were then used for DRM reaction. Among the developed catalysts, the catalyst produced following calcination at 500 °C (Ni-La-500) has shown stable and high CH 4 conversion rates under DRM conditions at 800 °C with negligible carbon formation at elevated gas hourly space velocities. Further, the catalytic performance of Ni-La-500 catalyst (sonicated) was compared to the physically mixed MOFs derived catalyst (Ni-La-500-PM), conventional wetness impregnated catalyst (Ni-La-500 WI), Ni-MOF derived unsupported catalyst (Ni-500), and lower Ni concentration catalyst (sonicated, 10Ni-La-500). The observed CH 4 conversion rates at 50,000 mL·g cat –1·h−1 GHSV are 81.8, 67.9, 85.4, 34.7, and 57.9 % for Ni-La-500, Ni-La-500 PM, Ni-La-500 WI, Ni-500, and 10Ni-La-500 catalysts, respectively after 24 h of DRM reaction. With isotopic studies, it was found that the 18O exchange rate was higher in case of Ni-La-500-PM catalyst (8.1 mmol·g−1) as compared to Ni-La-500 catalyst (5.5 mmol·g−1). Prior interaction between MOFs, calcination temperatures, reaction conditions, and the carbon pathways during catalytic activity dictates the conversion rates and selectivity of the products. Overall, with the herein proposed approach of MOF-derived supported catalysts exceptional conversion rates and stability during the DRM reaction with nominal coking and sintering were demonstrated, solving the two major challenges faced by conventional and unsupported catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni incorporated Al 2 O 3 -zeolite beta composites were synthesized via facile one-step method. • Al 2 O 3 to BZ affects Ni particle size, Al local environments and acid sites. • 31P NMR revealed that Bronsted to Lewis acid ratio dramatically altered with Al 2 O 3 addition • Al 2 O 3 modified Ni composites exhibit superior catalytic performance in HDO of palm oil. • Strong metal-support interactions prevent sintering of Ni particles and less coke formation The hydrodeoxygenation (HDO) of bio-oil is one of the potential approaches to produce green diesel. However, HDO catalyst requires the development of bifunctionality which translates to the simultaneous presence of acidic and metal sites for desired catalytic activity and selectivity. Zeolites and their composites are attractive candidates for the conversion of biomass to fuels. In the present work, a series of Ni-incorporated Al 2 O 3 -zeolite beta bifunctional composite catalysts with distinct Al 2 O 3 (25–75 wt%) and Ni contents (5–15 wt%) were synthesized via a facile one-pot method directly from nickel acetate, nano-boehmite (γ-AlO(OH)) and the NH 4 + form of beta zeolite (NH 4 +-BZ). The nano-boehmite particles, due to the positive charges on their surface, electrostatically attract negatively charged beta zeolite crystals, which leads to the assembly of a hierarchical pore structure upon calcination. Interestingly, the composite catalysts synthesized were quite homogeneous with uniform dispersion of Ni particles. All composite catalysts were thoroughly characterized using XRD, SEM-EDX, SEM-mapping, HR-TEM, H 2 -TPR, H 2 -TPD, NH 3 -TPD, XPS, 31P MAS NMR, 27Al MAS NMR and N 2 sorption analysis. The synthesized composite catalysts with distinct Al 2 O 3 contents showed diverse textural properties, distinct nature of acid sites and improved performance in hydrodeoxygenation of palm oil. Particularly, the Ni/BZ-Al50 (with BZ:Al 2 O 3 = 50:50) composite catalyst significantly enhanced the conversion of palm oil (up to 90%) and yield of n-C 15 -C 18 hydrocarbons (up to 69%) at moderate temperature of 375 °C as compared to 10Ni/BZ catalyst (Conv. = 75%, yield of n-C 15 -C 18 = 52%). The higher catalytic performance realized with composite catalysts can be ascribed to its hierarchical pore structure, moderate acidity (chemisorption studies), tuned acid sites nature (solid state NMR) and homogeneous distribution of active Ni sites (H 2 chemisorption) which helps to improve product selectivity by minimizing side reactions. The time-on-stream (TOS) experiments were carried out up to 20 h which clearly showed that composite catalysts are more stable suggesting the lower amount of coke deposition (TPO studies) and suppression of metal sintering. [ABSTRACT FROM AUTHOR]

Abstract: A method for the preparation of NiO and Nb–NiO nanocomposites is developed, based on the slow oxidation of a nickel-rich Nb–Ni gel obtained in citric acid. The resulting materials have higher surface areas than those obtained by the classical evaporation method from nickel nitrate and ammonium niobium oxalate. These consist in NiO nanocrystallites (7–13nm) associated, at Nb contents >3at.%., with an amorphous thin layer (1–2nm) of a niobium-rich mixed oxide with a structure similar to that of NiNb2O6. Unlike bulk nickel oxides, the activity of these nanooxides for low-temperature ethane oxidative dehydrogenation (ODH) has been related to their redox properties. In addition to limiting the size of NiO crystallites, the presence of the Nb-rich phase also inhibits NiO reducibility. At Nb content >5at.%, Nb–NiO composites are thus less active for ethane ODH but more selective, indicating that the Nb-rich phase probably covers part of the unselective, non-stoichiometric, active oxygen species of NiO. This geometric effect is supported by high-resolution transmission electron microscopy observations. The close interaction between NiO and the thin Nb-rich mixed oxide layer, combined with possible restructuration of the nanocomposite under ODH conditions, leads to significant catalyst deactivation at high Nb loadings. Hence, the most efficient ODH catalysts obtained by this method are those containing 3–4at.% Nb, which combine high activity, selectivity, and stability. The impact of the preparation method on the structural and catalytic properties of Nb–NiO nanocomposites suggests that further improvement in NiO-catalyzed ethane ODH can be expected upon optimization of the catalyst. [Copyright &y& Elsevier]

Herein, 3D flower-like δ-MnO 2 , MXene and δ-MnO 2 /MXene in-situ hybrid (IH) composites were prepared (via hydrothermal and solution treatment methods) for the effective removal of Cr (VI) from the contaminated water. The effect of various experimental parameters including contact time, pH levels and initial Cr (VI) ions concentration was determined and compared under static conditions. The kinetics of Cr (VI) adsorption onto δ-MnO 2 , MXene, and IH confirmed the existence of a pseudo-second-order model. The obtained results reveal that the removal of Cr (VI) largely depends on the pH of the solution. The adsorption isotherm data fits best for Freundlich model, illustrating a multi-site adsorption mechanism of Cr (VI) ion on these adsorbents. The maximum Cr (VI) adsorption capacities onto δ-MnO 2 , MXene and IH are 235.65 mg g−1, 273.1 mg g−1 and 353.87 mg g−1, respectively. The study reveals that hetero-engineered approach of synthesizing transition metal oxides with MXenes provides abundant opportunities to remove contaminants from water with better efficiency due to reduction and electrostatic interaction. [ABSTRACT FROM AUTHOR]

The dislocation free InxAl1-xN nanowires (NWs) are grown on Si(111) by nitrogen plasma assisted molecular beam epitaxy in the temperature regime of 490 °C-610 °C yielding In composition ranges over 0.50 ≤ x ≤ 0.17. We study the optical properties of these NWs by spectroscopic ellipsometry (SE), photoluminescence, and Raman spectroscopies since they possesses minimal strain with reduced defects comparative to the planar films. The optical bandgap measurements of InxAl1-xN NWs are demonstrated by SE where the absorption edges of the NW samples are evaluated irrespective of substrate transparency. A systematic Stoke shift of 0.04-0.27 eV with increasing x was observed when comparing the micro-photoluminescence spectra with the Tauc plot derived from SE. The micro-Raman spectra in the NWs with x = 0.5 showed two-mode behavior for A1(LO) phonons and single mode behavior for E2H phonons. As for x = 0.17, i.e., high Al content, we observed a peculiar E2 H phonon mode splitting. Further, we observe composition dependent frequency shifts. The 77 to 600K micro-Raman spectroscopy measurements show that both AlN- and InN-like modes of A1(LO) and E2H phonons in InxAl1-xN NWs are redshifted with increasing temperature, similar to that of the binary III group nitride semiconductors. These studies of the optical properties of the technologically important InxAl1-xN nanowires will path the way towards lasers and light-emitting diodes in the wavelength of the ultra-violet and visible range. [ABSTRACT FROM AUTHOR]

Single‐atom metal (SA‐M) catalysts with high dispersion of active metal sites allow maximum atomic utilization. Conventional synthesis of SA‐M catalysts involves high‐temperature treatments, leading to low yield with a random distribution of atoms. Herein, a nature‐based facile method to synthesize SA‐M catalysts (M = Fe, Ir, Pt, Ru, Cu, or Pd) in a single step at ambient temperature, using the extracellular electron transfer capability of Geobacter sulfurreducens (GS), is presented. Interestingly, the SA‐M is coordinated to three nitrogen atoms adopting an MN3 on the surface of GS. Dry samples of SA‐Ir@GS without further heat treatment show exceptionally high activity for oxygen evolution reaction when compared to benchmark IrO2 catalyst and comparable hydrogen evolution reaction activity to commercial 10 wt% Pt/C. The SA‐Ir@GS exhibits the best water‐splitting performance compared to other SA‐M@GS, showing a low applied potential of 1.65 V to achieve 10 mA cm−2 in 1.0 M KOH with cycling over 5 h. The density functional calculations reveal that the large adsorption energy of H2O and moderate adsorption energies of reactants and reaction intermediates for SA‐Ir@GS favorably improve its activity. This synthesis method at room temperature provides a versatile platform for the preparation of SA‐M catalysts for various applications by merely altering the metal precursors. [ABSTRACT FROM AUTHOR]

Iron-doped titanium dioxide nanoparticles, with Fe/Ti atomic ratios from 0% to 10%, were synthesized by flame spray pyrolysis (FSP), employing a single-step method. Ferrocene, being nontoxic and readily soluble in liquid hydrocarbons, was used as the iron source, while titanium tetraisopropoxide (TTIP) was used as the precursor for TiO2. The general particle characterization and phase description were examined using ICP-OES, XRD, BET, and Raman spectroscopy, whereas the XPS technique was used to study the surface chemistry of the synthesized particles. For particle morphology, HRTEM with EELS and EDS analyses were used. Optical and magnetic properties were examined using UV–vis and SQUID, respectively. Iron doping to TiO2 nanoparticles promoted rutile phase formation, which was minor in the pure TiO2 particles. Iron-doped nanoparticles exhibited a uniform iron distribution within the particles. XPS and UV–vis results revealed that Fe2+ was dominant for lower iron content and Fe3+ was common for higher iron content and the iron-containing particles had a contracted band gap of ~1 eV lower than pure TiO2 particles with higher visible light absorption. SQUID results showed that doping TiO2 with Fe changed the material to be paramagnetic. The generated nanoparticles showed a catalytic effect for dye-degradation under visible light. [ABSTRACT FROM AUTHOR]

[Display omitted] • M−Al 2 O 3 /SiO 2 composite catalysts are superior HDO catalysts compared to the non-modified SiO 2 based one. • Ni and NiCo based catalyst favored deCOx pathway, whereas Co one favored HDO pathway. • DFT calculations showed that NiCo bimetallic catalyst favors stronger adsorption of oleic acid. • Higher charge transfer happens from the bimetallic surface to the oleic acid. The development of an effective hydrodeoxygenation (HDO) catalyst is crucial for controlling product selectivity and catalyst stability. In this study, we synthesized monometallic (Ni and Co), as well as a bimetallic, NiCo embedded mesoporous composite catalysts using a simple one-step method involving meso -macroporous silica, boehmite, nickel acetate, and cobalt acetate. The synthesized range of catalysts (5, 10, 15 wt% Ni, 10 wt% Co, 10 wt% NiCo) were thoroughly characterized by various techniques. The characterization results showed that the present method leads to the growth of nano-catalyst on porous silica surface (M−Al 2 O 3 /SiO 2, M = Ni, Co, NiCo). These composites exhibited strong metal-support interaction, improved surface and texture properties and significant amount of weak to medium acid sites. The M−Al 2 O 3 /SiO 2 composite catalysts demonstrated improved catalytic performance in the HDO of oleic acid. At temperature of 375 °C, the conversion trend of catalysts followed the order; 10NiCo-Al 2 O 3 /SiO 2 (89%) > 10Ni-Al 2 O 3 /SiO 2 (87%) > 10Co-Al 2 O 3 /SiO 2 (85%) > 10Ni/SiO 2 (81%). Moreover, the yield of C 15 -C 18 hydrocarbons was substantially enhanced at moderate temperature compared to unmodified silica support. Time-on-stream experiments further confirmed the relative stability of the composite catalysts over a period of 20 h. Furthermore, density functional theory (DFT) ab initio calculations were performed where the adsorption of oleic acid on icosahedral monometallic M 13 (M = Co or Ni) and bimetallic N i 2 C o 2 nanocluster deposited on γ-Al 2 O 3 (1 1 0) support was investigated. The adsorption strength for the most stable conformations followed the order: N i 13 /amorphous SiO 2 > N i 2 C o 2 /Al 2 O 3 > C o 13 /Al 2 O 3 > N i 13 /Al 2 O 3. Bader charge transfer analysis indicated higher charge transfer at the interfaces of γ-Al 2 O 3 A l 2 O 3 (1 1 0) supported catalysts compared to N i 13 /amorphous SiO 2 surface. [ABSTRACT FROM AUTHOR]

The direct conversion of propane into aromatics (BTX) using modified ZSM-5 was achieved with a strategy of “catalysis by design”. In contrast to the classical mode of action of classical aromatization catalysts which are purely based on acidity, we have designed the catalyst associating two functions: One function (Ti-hydride) was selected to activate the C–H bond of propane by σ-bond metathesis to further obtain olefin by β-H elimination and the other function (Brønsted acid) being responsible for the oligomerization, cyclization, and aromatization. This bifunctional catalyst was obtained by selectively grafting a bulky organometallic complex of tetrakis(neopentyl)titanium (TiNp4) at the external surface (external silanol (≡Si–OH) group) of [H-ZSM-5300] to obtain [Ti/ZSM-5] catalyst 1. This metal was chosen to activate the C–H bond of paraffin at the periphery of the ZSM-5 while maintaining the Brønsted acid properties of the internal [H-ZSM-5] for oligomerization, cyclization, and aromatization. Catalyst 2 [Ti–H/ZSM-5] was obtained after treatment under H2 at 550 °C of freshly prepared catalyst 1 ([Ti/ZSM-5]) and catalyst 1 was thoroughly characterized by ICP analysis, DRIFT, XRD, N2-physisorption, multinuclear solid-state NMR, XPS and HR-TEM analysis including STEM imaging. The conversion of propane to aromatics was studied in a dynamic flow reactor. With the pristine [H-ZSM-5300] catalyst, the conversion of propane is very low. However, with [Ti–H/ZSM-5] catalyst 2 under the same reaction conditions, the conversion of propane remains significant during 60 h of the reaction (ca. 22%). Furthermore, the [Ti–H/ZSM-5] catalyst shows a good and stable selectivity (55%) for aromatics (BTX) of time on stream. With 2, it was found that the Ti remains at the periphery of the [H-ZSM-5] even after reaction time. [ABSTRACT FROM AUTHOR]

Abstract: Poly (3‐hexylthiophene) (P3HT) was an early frontrunner in the development of donor polymers to be used in organic photovoltaics. A relatively straightforward and inexpensive synthesis suggests that it may be the most viable donor polymer to use in large‐scale commercial organic solar cells. Replacing fullerenes with new electron acceptors has led to significant improvements in device performance and stability, with devices now able to exceed an efficiency of 7%. Past studies have reported a dependence of device performance on the molecular weight of the polymer in fullerene‐containing blends, however, with nonfullerene acceptors now showing promise a similar study was needed. P3HT blends, with two nonfullerene acceptors (O‐IDTBR and EH‐IDTBR), were probed using a number of polymer batches with varying molecular weights. O‐IDTBR was shown to exhibit a dependence on the polymer molecular weight, with optimal performance achieved with a 34 kDa polymer, while EH‐IDTBR displayed an independence in performance with varying polymer molecular weight. Probing the thermal and morphological behavior of the P3HT:O‐IDTBR blends suggests that an optimal morphology with pronounced donor and acceptor domains was only achieved with the 34 kDa polymer, and a greater degree of mixing was exhibited in the other blends, likely leading to poorer device performance. [ABSTRACT FROM AUTHOR]

Well-defined silica supported bimetallic catalysts Pt 100- x Pd x were prepared by Surface Organometallic Chemistry (SOMC) and Ionic-Exchange (IE) methods. For all investigated catalysts, iso -butane reaction with hydrogen under differential conditions led to the formation of methane and propane, n-butane, and traces of iso -butylene. The total reaction rate decreased with increasing the Pd loading for both catalysts series as a result of decreasing turnover rate of both isomerization and hydrogenolysis. In the case of Pt 100- x Pd x (SOMC) catalysts, the experimental results in combination with DFT calculations suggested a selective coverage of Pt (1 0 0) surface by agglomerated Pd atoms like “ islands ”, assuming that each metal roughly keeps its intrinsic catalytic properties with relatively small electron transfer from Pt to Pd in the case of Pt-rich sample and from Pd to Pt in the case of Pd-rich sample. For the PtPd catalysts prepared by IE, the catalytic behavior could be explained by the formation of a surface alloy between Pt and Pd in the case of Pd-rich sample and by the segregation of a small amount of Pd on the surface in the case of Pt-rich sample, as demonstrated by TEM, EXAFS and DFT. The catalytic results were explained by a structure activity relationship based on the proposed mechanism of C H bond and C C bond activation and cleavage for iso -butane hydrogenolysis, isomerization, cracking and dehydrogenation. [ABSTRACT FROM AUTHOR]

Abstract: Periodic mesoporous organosilica nanoparticles emerge as promising vectors for nanomedicine applications. Their properties are very different from those of well‐known mesoporous silica nanoparticles as there is no silica source for their synthesis. So far, they have only been synthesized from small bis‐silylated organic precursors. However, no studies employing large stimuli‐responsive precursors have been reported on such hybrid systems yet. Here, the synthesis of porphyrin‐based organosilica nanoparticles from a large octasilylated metalated porphyrin precursor is described for applications in near‐infrared two‐photon‐triggered spatiotemporal theranostics. The nanoparticles display unique interconnected large cavities of 10–80 nm. The framework of the nanoparticles is constituted with J‐aggregates of porphyrins, which endows them with two‐photon sensitivity. The nanoparticle efficiency for intracellular tracking is first demonstrated by the in vitro near‐infrared imaging of breast cancer cells. After functionalization of the nanoparticles with aminopropyltriethoxysilane, two‐photon‐excited photodynamic therapy in zebrafish is successfully achieved. Two‐photon photochemical internalization in cancer cells of the nanoparticles loaded with siRNA is also performed for the first time. Furthermore, siRNA targeting green fluorescent protein complexed with the nanoparticles is delivered in vivo in zebrafish embryos, which demonstrates the versatility of the nanovectors for biomedical applications. [ABSTRACT FROM AUTHOR]

The valence and conduction band offsets (VBO and CBO) at the semiconductor heterojunction are crucial parameters to design the active region of contemporary electronic and optoelectronic devices. In this report, to study the band alignment parameters at the In0.15Al0.85N/MoS2 lattice matched heterointerface, large area MoS2 single layers are chemical vapor deposited on molecular beam epitaxial grown In0.15Al0.85N films and vice versa. We grew InAlN having an in-plane lattice parameter closely matching with that of MoS2. We confirm that the grown MoS2 is a single layer from optical and structural analyses using micro-Raman spectroscopy and scanning transmission electron microscopy. The band offset parameters VBO and CBO at the In0.15Al0.85N/MoS2 heterojunction are determined to be 2.0860.15 and 0.6060.15 eV, respectively, with type-I band alignment using high-resolution x-ray photoelectron spectroscopy in conjunction with ultraviolet photoelectron spectroscopy. Furthermore, we design a MoS2 quantum well structure by growing an In0.15Al0.85N layer on MoS2/In0.15Al0.85N type-I heterostructure. By reducing the nitrogen plasma power and flow rate for the overgrown In0.15Al0.85N layers, we achieve unaltered structural properties and a reasonable preservation of photoluminescence intensity with a peak width of 70 meV for MoS2 quantum well (QW). The investigation provides a pathway towards realizing large area, air-stable, lattice matched, and eventual high efficiency In0.15Al0.85N/ MoS2/In0.15Al0.85N QW-based light emitting devices. [ABSTRACT FROM AUTHOR]

The delivery of large cargos of diameter above 15 nm for biomedical applications has proved challenging since it requires biocompatible, stably-loaded, and biodegradable nanomaterials. In this study, we describe the design of biodegradable silica-iron oxide hybrid nanovectors with large mesopores for large protein delivery in cancer cells. The mesopores of the nanomaterials spanned from 20 to 60 nm in diameter and post-functionalization allowed the electrostatic immobilization of large proteins (e.g. mTFP-Ferritin, ~ 534 kDa). Half of the content of the nanovectors was based with iron oxide nanophases which allowed the rapid biodegradation of the carrier in fetal bovine serum and a magnetic responsiveness. The nanovectors released large protein cargos in aqueous solution under acidic pH or magnetic stimuli. The delivery of large proteins was then autonomously achieved in cancer cells via the silica-iron oxide nanovectors, which is thus a promising for biomedical applications. [ABSTRACT FROM AUTHOR]

For overall water-splitting systems, it is essential to establish O2-insensitive cathodes that allow cogeneration of H2 and O2. An acid-tolerant electrocatalyst is described, which employs a Mo-coating on a metal surface to achieve selective H2 evolution in the presence of O2. In operando X-ray absorption spectroscopy identified reduced Pt covered with an amorphous molybdenum oxyhydroxide hydrate with a local structural order composed of polyanionic trimeric units of molybdenum(IV). The Mo layer likely hinders O2 gas permeation, impeding contact with active Pt. Photocatalytic overall water splitting proceeded using MoO x/Pt/SrTiO3 with inhibited water formation from H2 and O2, which is the prevailing back reaction on the bare Pt/SrTiO3 photocatalyst. The Mo coating was stable in acidic media for multiple hours of overall water splitting by membraneless electrolysis and photocatalysis. [ABSTRACT FROM AUTHOR]

For overall water-splitting systems, it is essential to establish O2-insensitive cathodes that allow cogeneration of H2 and O2. An acid-tolerant electrocatalyst is described, which employs a Mo-coating on a metal surface to achieve selective H2 evolution in the presence of O2. In operando X-ray absorption spectroscopy identified reduced Pt covered with an amorphous molybdenum oxyhydroxide hydrate with a local structural order composed of polyanionic trimeric units of molybdenum(IV). The Mo layer likely hinders O2 gas permeation, impeding contact with active Pt. Photocatalytic overall water splitting proceeded using MoO x/Pt/SrTiO3 with inhibited water formation from H2 and O2, which is the prevailing back reaction on the bare Pt/SrTiO3 photocatalyst. The Mo coating was stable in acidic media for multiple hours of overall water splitting by membraneless electrolysis and photocatalysis. [ABSTRACT FROM AUTHOR]

Continuous flow chemistry is used to trap the nucleation and growth stages of platinum–nickel nano-octahedra with second time resolution and high throughputs to probe their properties ex situ. The growth starts from poorly crystalline particles (nucleation) at 5 seconds, to crystalline 1.5 nm particles bounded by the {111}-facets at 7.5 seconds, followed by truncation and further growth to octahedral nanoparticles at 20 seconds. [ABSTRACT FROM AUTHOR]

Recent interest in two-dimensional materials has resulted in ultra-thin devices based on the transfer of transition metal dichalcogenides (TMDs) onto other TMDs or III-nitride materials. In this investigation, we realized p-type monolayer (ML) MoS2, and intrinsic GaN/p-type MoS2 heterojunction by the GaN overgrowth on ML-MoS2/c-sapphire using the plasma-assisted molecular beam epitaxy. A systematic nitrogen plasma (N*2) and gallium (Ga) irradiation studies are employed to understand the individual effect on the doping levels of ML-MoS2, which is evaluated by micro- Raman and high-resolution X-Ray photoelectron spectroscopy (HRXPS) measurements. With both methods, p-type doping was attained and was verified by softening and strengthening of characteristics phonon modes E1 2g and A1g from Raman spectroscopy. With adequate N*2-irradiation (3 min), respective shift of 1.79 cm-1 for A2gand 1.11 cm-1 for E1 2gare obtained while short term Ga-irradiated (30 s) exhibits the shift of 1.51 cm-1 for A1g and 0.93 cm-1 for E1 2g. Moreover, in HRXPS valence band spectra analysis, the position of valence band maximum measured with respect to the Fermi level is determined to evaluate the type of doping levels in ML-MoS2. The observed values of valance band maximum are reduced to 0.5, and 0.2 eV from the intrinsic value of ≈1.0 eV for N*2- and Ga-irradiated MoS2 layers, which confirms the p-type doping of ML-MoS2. Further p-type doping is verified by Hall effect measurements. Thus, by GaN overgrowth, we attained the building block of intrinsic GaN/p-type MoS2 heterojunction. Through this work, we have provided the platform for the realization of dissimilar heterostructure via monolithic approach. [ABSTRACT FROM AUTHOR]

We describe biodegradable mesoporous hybrid nanoparticles (NPs) in the presence of proteins and their applications for drug delivery. We synthesized oxamide phenylene-based mesoporous organosilica nanoparticles (MON) in the absence of a silica source which had remarkably high organic content and high surface areas. Oxamide functions provided biodegradability in the presence of trypsin model proteins. MON displayed exceptionally high payloads of hydrophilic and hydrophobic drugs (up to 84 wt %), and a unique zero premature leakage without the pore capping, unlike mesoporous silica. MON were biocompatible and internalized into cancer cells for drug delivery. [ABSTRACT FROM AUTHOR]

Designing supported well-defined bis(carbene) complexes remains a key challenge in heterogeneous catalysis. The reaction of W(≡C tBu)(CH2 tBu)3 with amine-modified mesoporous SBA15 silica, which has vicinal silanol/silylamine pairs [(≡SiOH)(≡SiNH2)], leads to [(≡SiNH2−)(≡SiO−)W(≡CH tBu)(CH2 tBu)2] and [(≡SiNH2−)(≡SiO−)W(=CH tBu)2(CH2 tBu). Variable temperature, 1H-1H 2D double-quantum, 1H-13C HETCOR, and HETCOR with spin diffusion solid-state NMR spectroscopy demonstrate tautomerization between the alkyl alkylidyne and the bis(alkylidene) on the SBA15 surface. Such equilibrium is possible through the coordination of W to the surface [(≡Si−OH)(≡Si−NH2)] groups, which act as a [N,O] pincer ligand. DFT calculations provide a rationalization for the surface-complex tautomerization and support the experimental results. This direct observation of such a process shows the strong similarity between molecular mechanisms in homogeneous and heterogeneous catalysis. In propane metathesis (at 150 °C), the tungsten bis(carbene) tautomer is favorable, with a turnover number (TON) of 262. It is the highest TON among all the tungsten alkyl-supported catalysts. [ABSTRACT FROM AUTHOR]