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The purpose of the work is to design a novel impedance adapter to set up a mono‐cone standard field generation system with a large clear time and a large dynamic range. To transform the impedance from 50 Ω (the output impedance of the signal generator) to 75 Ω (the input impedance of the cone), the gradient structures with 11 sections are designed for the impedance adapter. The measured VSWR of the system is below 1.5 from 300 to 2.25 GHz. The insertion loss of the designed is about −35 dB. The system with the designed impedance adapter works well. This is validated by the results of the standard open‐air test site in National Institute of Metrology, China. [ABSTRACT FROM AUTHOR]

Developing sustainable energy resources is one of the most urgent missions for human beings as increasing energy demand is in drastic conflict with limited global fossil fuels. Among the various types of sustainable energy resources, solar energy is considered to be promising due to its inexhaustible supply, universality, high capacity, and environmental friendliness. However, natural solar irradiation is decentralized, intermittent and fluctuates constantly. Therefore, effective utilization of solar energy in a clean, economic, and convenient way remains a grand challenge. [ABSTRACT FROM AUTHOR]

Solar water splitting provides a clean and renewable approach to produce hydrogen energy. In recent years, single-crystal semiconductors such as Si and InP with narrow band gaps have demonstrated excellent performance to drive the half reactions of water splitting through visible light due to their suitable band gaps and low bulk recombination. This Minireview describes recent research advances that successfully overcome the primary obstacles in using these semiconductors as photoelectrodes, including photocorrosion, sluggish reaction kinetics, low photovoltage, and unfavorable planar substrate surface. Surface modification strategies, such as surface protection, cocatalyst loading, surface energetics tuning, and surface texturization are highlighted as the solutions. [ABSTRACT FROM AUTHOR]

Die Wasserspaltung mittels Sonnenenergie bietet einen sauberen und erneuerbaren Ansatz für die Produktion von Wasserstoff. Einkristalline Halbleiter mit kleinen Bandlücken und geringer Ladungsträgerrekombination, wie Si und InP, erweisen sich als sehr gut geeignet, die Halbreaktionen der Wasserspaltung – die Wasserstoff ‐ (HER) und Sauerstoffentwicklung (OER) – unter Einwirkung von sichtbarem Licht zu fördern. Durch die Verwendung dieser Halbleiter als Photoelektroden konnte in jüngster Zeit eine Reihe von Problemen im Zusammenhang mit Photokorrosion, langsamen Reaktionskinetiken, niedrigen Photospannungen und ungünstigen planaren Substratoberflächen gelöst werden. Dieser Kurzaufsatz fasst den aktuellen Stand der Forschungen zusammen, mit Schwerpunkt auf Oberflächenmodifizierungsstrategien, wie z. B. Oberflächenschützung, Beladung mit Kokatalysatoren, Abstimmung der Oberflächenenergetiken und Oberflächentexturierung. Mit passenden Bandlücken und geringer Ladungsträgerrekombination haben sich einkristalline Halbleiter als exzellente Materialien für die solare Wasserspaltung bewährt. Dieser Kurzaufsatz beschreibt jüngste Fortschritte bei der Verwendung dieser Halbleiter als Photoelektroden, mit Schwerpunkt auf Schutzschichten, Kokatalysatoren und Oberflächentexturierung. [ABSTRACT FROM AUTHOR]

A simple theoretical expression is described to demonstrate the thermal response characteristics of the thermal wave field in the frequency domain by means of the Green's function method. The defect detectivity using lock-in thermography (LIT) for a carbon-fiber-reinforced polymer (CFRP) with a subsurface defect is investigated, and theoretical analysis results of the defect depth resolution as well as the detection range determined by the thermal wave phase information have shown good agreement with experimental results. The detectable size of a lamination defect in a CFRP has also been studied using lock-in thermographic imaging. The experimental results indicate that LIT is reliably available for evaluating subsurface defects of a CFRP panel at the appropriate modulation frequency, and the defect diameter-to-depth ratio can be as low as 3.0. [ABSTRACT FROM AUTHOR]

Abstract: A combined theoretical and experimental approach is reported using thermal-wave radar imaging (TRWI) for carbon fiber reinforced polymer (CFRP) with subsurface defects inspection. The multi-transform technique (Fourier transform, FT; Hilbert transform, HT; and cross-correlation, CC) is applied to extract the characteristics of thermal-wave signal. Experimental results indicate that the multi-transform technique of thermal-wave signal is available for detecting the subsurface defect. For the shallow defect (defect depth ≤1mm), the delay time image of CC exhibits high contrast, and the phase image of FT has high SNR at the right frequency component. For the deep defect (defect depth 2.0mm), the phase images of HT have both high contrast and large SNR value. [Copyright &y& Elsevier]

Highlights: [•] LFM-UTWI was developed to detect the subsurface defects. [•] Main peak value image of CC operation of LFM-UTWI has high signal–noise ratios. [•] LFM-UTWI has better defect detectability for subsurface defects than ULIT. [ABSTRACT FROM AUTHOR]

Highlights: [•] LITI measurement is in good agreement with FEM analysis for TSA on MCS. [•] An artificial neural network was proposed to determine the component of MCS. [•] LITI is an attractive tool for stress distribution analysis of MCS. [Copyright &y& Elsevier]

Water has important effects on several reactions occurring over gold catalysts. In this work, we review studies demonstrating the interactions of water in surface chemistry and catalysis over gold, with specific emphasis on the ability of water to enhance activity for the CO oxidation reaction and the role water plays in the mechanism of the water-gas shift reaction. Water significantly influences these and other catalytic reactions over gold catalysts. [ABSTRACT FROM AUTHOR]

Abstract: Diphenyl carbonate (DPC) is considered as a substitution for phosgene to synthesize polycarbonate resins. Conventional production of DPC involves reactions of phosgene and phenol. However, the phosgene process has drawbacks such as environmental and safety problems associated with using highly toxic phosgene as the reagent, which results in the formation of chlorine salts, and copious amounts of methylene chloride as the solvent. For these reasons, environmentally friendly processes for DPC production without using phosgene have been proposed and developed in the past decades. So far, the most promising alternatives appear to be the transesterification of dimethyl carbonate (DMC) and phenol, the direct oxidative carbonylation of phenol, and transesterification of dialkyl oxalates and phenol. This paper attempts to review recent literature concerning process design and catalytic chemistry for these phosgene-free approaches. The advantages and disadvantages are discussed for each reaction. Strategies to overcome potential problems are provided. The perspectives to improve catalytic efficiency of phosgene-free process are proposed. [Copyright &y& Elsevier]

Abstract: The morphology and microstructure of multi-walled carbon nanotubes (MWCNTs) were modified using ethanol as a mild gas reactant. The etching by OH radicals and deposition of C radicals on the carbon nanotubes were considered to be responsible for the modification of the MWCNT structures and the formation of new carbon nanostructures. The effects of etching and deposition on the MWCNTs were confirmed by using methanol as another gas reactant; this molecule has a higher ratio of hydroxyl radicals to carbon atoms than ethanol. In addition, water vapor, containing no carbon atoms in the molecule, was also applied to etch the MWCNTs as a weak oxidant which resulted in stronger etching effects on the MWCNTs than methanol and ethanol. [Copyright &y& Elsevier]

Abstract: The transesterification of dimethyl oxalate (DMO) with phenol over stannum modified TS-1 was conducted to prepare methyl phenyl oxalate (MPO) and diphenyl oxalate (DPO), which could be used to produce diphenyl carbonate (DPC). The component, structure and phase of TS-1 catalysts with various Sn loadings were investigated. The relationship between the catalytic properties and the Sn loadings was discussed. The results indicated that, although the Sn-modified TS-1 catalysts had fewer Lewis acid sites than the unmodified TS-1, its catalytic activity was increased greatly by the interaction of Sn with Ti–O–SiO3 weak Lewis acid centers. The catalyst of TS-1 with 2 wt% Sn loadings performed best, giving 50.3% conversion of dimethyl oxalate and 99.2% selectivity to the target products. By means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX), the relationship between the catalytic properties and the structure of Sn dispersed on the surface of TS-1 was studied in detail. At Sn loadings below 2wt%, Sn was highly dispersed, but at higher loadings it was crystallized into bulk tin dioxide, where the interaction between Ti and Sn was not evidently observed, leading to decreased catalytic activity. XPS results showed that Ti could not be detected even at 1wt% Sn loadings. EDX results indicated that the content of Ti on the surface decreased with increasing Sn loadings, but the decrease in Ti content was much less than the increase in Sn content. Moreover, NH3-TPD and FTIR analyses of adsorbed pyridine showed that there were only weak Lewis acid centers on all catalysts and the Sn loadings hardly affected the acid strength of the catalysts. [Copyright &y& Elsevier]

Abstract: A new preparation method for supported MoO3 catalyst, slurry impregnation, has been described and compared with the conventional impregnation method. Slurry MoO3/water is used instead of the solution ammonium heptamolybdate, AHM [(NH4)6Mo7O24]. The MoO3/γ-alumina, MoO3/active carbon, and MoO3/silica catalysts with different Mo loadings were prepared by slurry and by conventional method. The low solubility of MoO3 was sufficient to transport molybdenum species from solid MoO3 to the adsorbed phase. The equilibrium was achieved after several hours at 95°C based on the loading amount of molybdenum. Only the process of drying was needed; calcination was not necessary and was left out. This is an important advantage for active carbon support because oxidative degradation of active carbon impregnated by molybdena starts at a relatively low temperature of about 250°C during calcination on air. The activity was tested in the transesterification of dimethyl oxalate (DMO) and phenol at 180°C. The dependences of catalytic activity on Mo loadings for the slurry prepared catalysts were similar to the dependences for the samples prepared by the conventional impregnation method with AHM. The activities of the slurry impregnation MoO3/γ-Al2O3 catalysts were almost the same as those of catalysts prepared conventionally. Although the performances of slurry impregnation MoO3/SiO2 catalysts for transesterification of DMO were slightly better than those of the corresponding catalysts prepared by conventional impregnation, no waste solution and no calcining nitrogenous gases were produced. Therefore, we conclude that the new slurry impregnation method for preparation of supported molybdenum catalysts is an environmentally friendly process and a simple, clean alternative to the conventional preparation using solutions of (NH4)6Mo7O24. The present work will lead to a remarkable improvement in the catalyst preparation for the transesterification reaction. [Copyright &y& Elsevier]

The transesterification of dimethyl oxalate (DMO) with phenol to methyl phenyl oxalate (MPO) and diphenyl oxalate (DPO) was carried out in liquid phase under facile catalytic conditions. A series of bimetallic, MoO3–SnO2/SiO2, catalysts with various Mo and Sn content were prepared by sequential impregnation of cationic Mo species and cationic Sn complexes using impregnation method. The effects of mass ratio of Mo:Sn, amount of Sn additive, and Mo(Sn) laoding amount on activities of transesterification of dimethyl oxalate with phenol were investigated. The evaluation results showed that MoO3–SnO2/SiO2 catalyst with 14 wt% Mo(Sn) content performed best, giving 74.6% DMO conversion and 99.5% selectivity to MPO and DPO. This new heterogeneous catalyst provided not only an excellent selectivity (99% to MPO and DPO) and high yield of MPO and DPO but also a simple and practical protocol for DPC synthesis. [Copyright &y& Elsevier]

A series of MoO3/SiO2 catalysts were prepared with Mo loadings ranging from 1 to 16 wt% and applied to the transesterification of dimethyl oxalate (DMO) with phenol. The results showed that the catalyst of MoO3/SiO2 with 1 wt% Mo content performed best, giving 54.6% conversion of DMO and 99.6% selectivity to target products, methyl phenyl oxalate (MPO) and diphenyl oxalate (DPO). The surface properties were investigated by means of X-ray diffraction (XRD), X-ray photoelectron (XPS), BET specific surface area, temperature-programmed desorption (TPD) of ammonia, and FTIR analysis of adsorbed pyridine. XPS and XRD analyses indicated that Mo(VI) species was highly dispersed at low Mo loading and MoO3 of the crystal structure appeared at higher loading. NH3-TPD characterization and FTIR analysis of adsorbed pyridine demonstrated that only Lewis weak acids were present on catalyst surface and the amount of Mo loading has little effect on the strength of the surface acid on MoO3/SiO2. The catalytic results exhibited that the synergetic effect of Mo active centers with weak Lewis acid sites catalyzed transesterification of DMO with phenol. [Copyright &y& Elsevier]

In this paper, the detection reliability of optical bidirectional thermal wave radar imaging (BTWRI) for glass fiber reinforced polymer (GFRP) laminates with subsurface defects using various imaging algorithms was quantitatively investigated. A set of GFRP laminates with artificial defects were prepared and inspected. Three frequently-used imaging algorithms (cross-correlation, CC; chirp lock-in, CLI; and Hilbert transform mean, HTM) were applied to construct characteristic images. An analysis for probability of detection (POD) was carried out based on the hit/miss data obtained by comparing the defect contrasts and noise thresholds of characteristic images. A multi-characteristic combination (MCC) method integrating the advantages of each algorithm was proposed. The reliability assessment of optical BTWRI for inspecting GFRP laminate defects was compared by the defect diameter-to-depth ratio (r 90/95) at 90% POD with 95% confidence level and detection rates (DRs). The comparison results show that the MCC method exhibits enhanced reliability with smaller r 90/95 and higher DRs at a series of determination thresholds compared with CLI, HTM, and CC algorithms. [ABSTRACT FROM AUTHOR]

• C/GFRP specimens are tested using bidirectional thermal wave radar imaging. • Multiple imaging algorithms are used for subsurface defect detection and compared by SNR performance. • A modified correlation phase algorithm (Analytical chirp correlation, ACC) is presented for calculation load reduction. • The optimal image of ACC algorithm has a significant improvement on SNR performance. In this paper, the detection capability of laser-generated bidirectional thermal wave radar imaging (BTWRI) inspection for carbon/glass fiber reinforced polymer (C/GFRP) defects was quantitatively evaluated by signal-to-noise ratio (SNR) analysis of characteristic images. A low-power experimental system was devised, and the C/GFRP specimens with multi-scale diameter-to-depth ratio were tested. An improved imaging algorithm (analytical chirp correlation, ACC) was presented by applying analytical bidirectional chirp signal to extract the correlation phase and amplitude of thermal wave radar signal corresponding to the expected delay time. The optimal ACC detection image is obtained by the SNR comparison of characteristic images frame by frame. The conventional imaging inspection results of using cross-correlation (CC), cross-correlation phase (CCP), chirp lock-in (CLI), and Hilbert transform mean (HTM) algorithms were performed for SNR comparison. Experimental results indicate that the ACC algorithm displays almost the same detection capability as the traditional CCP algorithm by a simpler calculation process, and the optimal ACC detection image has a significant enhancement on SNR performance for C/GFRP subsurface defects compared with conventional imaging algorithms. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of energy-saving production plan for periodic forging heating furnaces in production systems. First, the heating furnace is divided into four stages and the causes of energy loss in each stage are analyzed. Based on the energy balance of the heating furnace, a general energy consumption model is built, which takes into account the energy income of the heating furnace, energy loss and effective energy of forging heating. On this basis, the optimization model of energy consumption cost, time cost minimization and furnace tolerance minimization, in the single machine production planning process for heating furnace, are put forward. Finally, considering the use of the heating furnace, at the level of decision-making, the heating processing task production order, the idle time and the heating furnace allowed, to retain the temperature time, are determined. In order to obtain the "near" optimal solution of the problem, a heuristic genetic algorithm is used to settle the dispute. First,First, the strength Pareto evolutionary algorithm 2 (SPEA2) is used to optimize the energy and time consumption. Following, the hierarchical solution method is used to further optimize furnace tolerance, thus deriving the better solution results, which are compared to the results obtained by the other four methods. Thus, the production scheme, under the three modes of high efficiency, energy-saving and comprehensive, is obtained. This model enables the operation manager to implement the production plan in different modes, during the production shift, while the decision-maker can make the choice according to the actual situation. Image 1 • The working stages of the resistance furnace are determined and the respective energy loss is analyzed. • A universal energy dissipation model based on energy balance of resistance furnace is established. • A multi-objective optimization model is proposed for the single machine production planning of resistance furnace. • A heuristic genetic algorithm is used to solve this problem. [ABSTRACT FROM AUTHOR]

• Integrated autoencoder with RNN to develop reduced-order machine learning models. • Developed probabilistic closed-loop stability results for reduced-order RNN-MPC. • Validated the closed-loop performance via a diffusion-reaction process example. In this work, we develop a model predictive control scheme for nonlinear systems using autoencoder-based reduced-order machine learning models. First, an autoencoder is developed for model order reduction by projecting the process states onto a low-dimensional space using data generated from open-loop simulations of the nonlinear system in the original high-dimensional space. Subsequently, reduced-order recurrent neural networks (RNN) are developed to capture the dominant dynamics of the nonlinear system using the low-dimensional data. Lyapunov-based model predictive control (MPC) scheme using RNN models in low-dimensional space is developed to stabilize the nonlinear system. Finally, a diffusion-reaction process example is used to demonstrate the effectiveness of the proposed reduced-order RNN modeling approach and RNN-based predictive control method. [ABSTRACT FROM AUTHOR]

Oxidative dehydrogenation of amines using heterogeneous gold catalysts has unanticipated potential; chemisorbed atomic oxygen is used to activate propylamine, producing propionitrile and/or propionaldehyde on a single-crystal Au(111) surface. [ABSTRACT FROM AUTHOR]

A systematic theoretical study probing the catalytic potential of metal-doped SnO2(110) was conducted. The incorporation of metals such as Zr, Ti, W, V, Hf, and Ge is shown to drive electron transfer to Sn. The increased charge of Sn is injected into anti-bonding orbitals, finely tuning the catalytic activity and reducing the overpotential to −0.34 V. AIMD simulations show the stability of the modified structures. This work sheds light on the rational design of low-cost metal oxides with a high catalytic performance for CO2ER to formate. [ABSTRACT FROM AUTHOR]

The structure of catalysts determines the performance of catalytic processes. Intrinsically, the electronic and geometric structures influence the interaction between active species and the surface of the catalyst, which subsequently regulates the adsorption, reaction, and desorption behaviors. In recent decades, the development of catalysts with complex structures, including bulk, interfacial, encapsulated, and atomically dispersed structures, can potentially affect the electronic and geometric structures of catalysts and lead to further control of the transport and reaction of molecules. This review describes comprehensive understandings on the influence of electronic and geometric properties and complex catalyst structures on the performance of relevant heterogeneous catalytic processes, especially for the transport and reaction over structured catalysts for the conversions of light alkanes and small molecules. The recent research progress of the electronic and geometric properties over the active sites, specifically for theoretical descriptors developed in the recent decades, is discussed at the atomic level. The designs and properties of catalysts with specific structures are summarized. The transport phenomena and reactions over structured catalysts for the conversions of light alkanes and small molecules are analyzed. At the end of this review, we present our perspectives on the challenges for the further development of structured catalysts and heterogeneous catalytic processes. [ABSTRACT FROM AUTHOR]

BiVO4 is one of the most promising candidates for photoelectrochemical water oxidation. However, the poor crystallinity and short hole diffusion length limit its charge separation. One bottleneck stems from the contradiction between high crystallinity and small particles via conventional furnace heating processes. This paper describes the design and fabrication of BiVO4 photoanodes via rapid thermal process (RTP), rather than furnace heating, to decouple the constraints between nucleation, crystallization, and growth processes of BiVO4. The higher heating ramp rate of RTP compared with furnace heating promotes the fast diffusion of reactant molecules, which elevates the nucleation rate above the particle growth rate of BiVO4, leading to small particles with high crystallinity. Moreover, the ultra‐high heating temperature makes it possible to crystallize the small BiVO4 particle within a short time. Thus, a high crystallinity can be obtained for the RTP‐treated BiVO4 while maintaining small particle size, achieving a charge separation efficiency of up to 82%, 30% higher than that of furnace‐treated BiVO4 photoanode. [ABSTRACT FROM AUTHOR]

Gas diffusion electrodes (GDEs) mediate the transport of reactants, products and electrons for the electrocatalytic CO2 reduction reaction (CO2RR) in membrane electrode assemblies. The random distribution of ionomer, added by the traditional physical mixing method, in the catalyst layer of GDEs affects the transport of ions and CO2. Such a phenomenon results in elevated cell voltage and decaying selectivity at high current densities. This paper describes a pre-confinement method to construct GDEs with homogeneously distributed ionomer, which enhances mass transfer locally at the active centers. The optimized GDE exhibited comparatively low cell voltages and high CO Faradaic efficiencies (FE > 90%) at a wide range of current densities. It can also operate stably for over 220 h with the cell voltage staying almost unchanged. This good performance can be preserved even with diluted CO2 feeds, which is essential for pursuing a high single-pass conversion rate. This study provides a new approach to building efficient mass transfer pathways for ions and reactants in GDEs to promote the electrocatalytic CO2RR for practical applications. [ABSTRACT FROM AUTHOR]

Surface and interfacial catalysis plays a vital role in chemical industries, electrochemistry and photochemical reactions. The challenges of modern chemistry are to optimize the chemical reaction processes and understand the detailed mechanism of chemical reactions. Since the early 1960s, the foundation of surface science systems has allowed the study of surface and interfacial phenomena on atomic/molecular level, and thus brought a number of significant developments to fundamental and technological processes, such as catalysis, material science and biochemistry, just to name a few. This themed issue describes the recent advances and developments in the fundamental understanding of surface and interfacial catalysis, encompassing areas of knowledge from metal to metal oxide, carbide, graphene, hexagonal boron nitride, and transition metal dichalcogenides under ultrahigh vacuum conditions, as well as under realistic reaction conditions. [ABSTRACT FROM AUTHOR]

Catalytic conversion of CO2 to produce fuels and chemicals is attractive in prospect because it provides an alternative to fossil feedstocks and the benefit of converting and cycling the greenhouse gas CO2 on a large scale. In today's technology, CO2 is converted into hydrocarbon fuels in Fischer–Tropsch synthesis via the water gas shift reaction, but processes for direct conversion of CO2 to fuels and chemicals such as methane, methanol, and C2+ hydrocarbons or syngas are still far from large-scale applications because of processing challenges that may be best addressed by the discovery of improved catalysts—those with enhanced activity, selectivity, and stability. Core–shell structured catalysts are a relatively new class of nanomaterials that allow a controlled integration of the functions of complementary materials with optimised compositions and morphologies. For CO2 conversion, core–shell catalysts can provide distinctive advantages by addressing challenges such as catalyst sintering and activity loss in CO2 reforming processes, insufficient product selectivity in thermocatalytic CO2 hydrogenation, and low efficiency and selectivity in photocatalytic and electrocatalytic CO2 hydrogenation. In the preceding decade, substantial progress has been made in the synthesis, characterization, and evaluation of core–shell catalysts for such potential applications. Nonetheless, challenges remain in the discovery of inexpensive, robust, regenerable catalysts in this class. This review provides an in-depth assessment of these materials for the thermocatalytic, photocatalytic, and electrocatalytic conversion of CO2 into synthesis gas and valuable hydrocarbons. [ABSTRACT FROM AUTHOR]

Construction of a "net‐zero‐emission" system through CO2 hydrogenation to methanol with solar energy is an eco‐friendly way to mitigate the greenhouse effect. Traditional CO2 hydrogenation demands centralized mass production for cost reduction with mass water electrolysis for hydrogen supply. To achieve continuous reaction with intermittent and fluctuating flow of H2 on a small‐scale for distributed application scenarios, modulating the catalyst interface environment and chemical adsorption capacity to adapt fluctuating reaction conditions is highly desired. This paper describes a distributed clean CO2 utilization system in which the surface structure of catalysts is carefully regulated. The Ni catalyst with unsaturated electrons loaded on In2O3 can reduce the dissociation energy of H2 to overcome the slow response of intermittent H2 supply, exhibiting a faster response (12 min) than bare oxide catalysts (42 min). Moreover, the introduction of Ni enhances the sensitivity of the catalyst to hydrogen, yielding a Ni/In2O3 catalyst with a good performance at lower H2 concentrations with a 15 times adaptability for wider hydrogen fluctuation range than In2O3, greatly reducing the negative impact of unstable H2 supplies derived from renewable energies. [ABSTRACT FROM AUTHOR]

Construction of a "net‐zero‐emission" system through CO2 hydrogenation to methanol with solar energy is an eco‐friendly way to mitigate the greenhouse effect. Traditional CO2 hydrogenation demands centralized mass production for cost reduction with mass water electrolysis for hydrogen supply. To achieve continuous reaction with intermittent and fluctuating flow of H2 on a small‐scale for distributed application scenarios, modulating the catalyst interface environment and chemical adsorption capacity to adapt fluctuating reaction conditions is highly desired. This paper describes a distributed clean CO2 utilization system in which the surface structure of catalysts is carefully regulated. The Ni catalyst with unsaturated electrons loaded on In2O3 can reduce the dissociation energy of H2 to overcome the slow response of intermittent H2 supply, exhibiting a faster response (12 min) than bare oxide catalysts (42 min). Moreover, the introduction of Ni enhances the sensitivity of the catalyst to hydrogen, yielding a Ni/In2O3 catalyst with a good performance at lower H2 concentrations with a 15 times adaptability for wider hydrogen fluctuation range than In2O3, greatly reducing the negative impact of unstable H2 supplies derived from renewable energies. [ABSTRACT FROM AUTHOR]

Water splitting for hydrogen production by harvesting sunlight is widely accepted as one of the most promising routes to relieve the energy crisis and environmental issues caused by excessive use of fossil fuels. Earth-abundant silicon (Si) is emerging as a suitable candidate for a photoelectrode material for efficient solar water splitting. This review describes the current status and prospects of single-crystal Si-based photoelectrodes in photoelectrochemical (PEC) water splitting for hydrogen production. We start with highlighting the recent achievements in single-crystal Si-based photocathodes and photoanodes for PEC water reduction and oxidation. We then discuss the recent progress in the design and fabrication of unbiased solar water splitting cells with single-crystal Si-based photoelectrodes. Finally, we provide an overview from the optimization of a single-crystal Si-based electrode (both a photocathode and a photoanode) to the integration of a full cell for unassisted overall solar water splitting. [ABSTRACT FROM AUTHOR]

Review: [emphasis on Si- and InP-based photocathodes; 53 refs. [ABSTRACT FROM AUTHOR]

Narrow‐band‐gap single‐crystal semiconductors have been considered inappropriate for solar water splitting largely because of the photocorrosion issue. However, several exciting breakthroughs have shown that the instability and other drawbacks of these materials can be overcome. In their Minireview on page 10718 ff., T. Wang and J. Gong describe recent research advances and highlight the most important approaches to using these semiconductors as efficient photoelectrodes. [ABSTRACT FROM AUTHOR]

Einkristalline Halbleiter mit kleiner Bandlücke galten lange als ungeeignet für die solare Wasserspaltung, vor allem wegen ihrer Neigung zur Photokorrosion. Mehrere Strategien wurden inzwischen jedoch entwickelt, um die Instabilität und andere Nachteile dieser Materialien zu überwinden. In ihrem Kurzaufsatz auf S. 10866 ff. beschreiben T. Wang und J. Gong aktuelle Fortschritte in diese Richtung und stellen die wichtigsten Ansätze zur Anwendung dieser Halbleiter als effiziente Photoelektroden heraus. [ABSTRACT FROM AUTHOR]

The article presents a study on ethanol selective oxidation to acetaldehyde in gold. It states that ethanol is a type of alcohol that can predict inexhaustible resource for replacing and lessening petrochemical reserves and can raise bulk chemicals through selective oxidation. Moreover, the results of the oxidative conversion using acetaldehyde of gold applying temperature-programmed desorption (TPD) and molecular beam reactive scatterings (MBRS) shows that ethanol passed on O-H bond cleavage.

Hydrogen is an essential energy carrier which will address the challenges posed by the energy crisis and climate change. Photoelectrochemical water splitting (PEC) is an important method for producing solar-powered hydrogen. The PEC tandem configuration harnesses sunlight as the exclusive energy source to drive both the hydrogen (HER) and oxygen evolution reactions (OER), simultaneously. Therefore, PEC tandem cells have been developed and gained tremendous interest in recent decades. This review describes the current status of the development of tandem cells for unbiased photoelectrochemical water splitting. The basic principles and prerequisites for constructing PEC tandem cells are introduced first. We then review various single photoelectrodes for use in water reduction or oxidation, and highlight the current state-of-the-art discoveries. Second, a close look into recent developments of PEC tandem cells in water splitting is provided. Finally, a perspective on the key challenges and prospects for the development of tandem cells for unbiased PEC water splitting are given. [ABSTRACT FROM AUTHOR]

Developing easily accessible descriptors is crucial but challenging to rationally design single‐atom catalysts (SACs). This paper describes a simple and interpretable activity descriptor, which is easily obtained from the atomic databases. The defined descriptor proves to accelerate high‐throughput screening of more than 700 graphene‐based SACs without computations, universal for 3–5d transition metals and C/N/P/B/O‐based coordination environments. Meanwhile, the analytical formula of this descriptor reveals the structure–activity relationship at the molecular orbital level. Using electrochemical nitrogen reduction as an example, this descriptor's guidance role has been experimentally validated by 13 previous reports as well as our synthesized 4 SACs. Orderly combining machine learning with physical insights, this work provides a new generalized strategy for low‐cost high‐throughput screening while comprehensive understanding the structure‐mechanism‐activity relationship. [ABSTRACT FROM AUTHOR]

Developing easily accessible descriptors is crucial but challenging to rationally design single‐atom catalysts (SACs). This paper describes a simple and interpretable activity descriptor, which is easily obtained from the atomic databases. The defined descriptor proves to accelerate high‐throughput screening of more than 700 graphene‐based SACs without computations, universal for 3–5d transition metals and C/N/P/B/O‐based coordination environments. Meanwhile, the analytical formula of this descriptor reveals the structure–activity relationship at the molecular orbital level. Using electrochemical nitrogen reduction as an example, this descriptor's guidance role has been experimentally validated by 13 previous reports as well as our synthesized 4 SACs. Orderly combining machine learning with physical insights, this work provides a new generalized strategy for low‐cost high‐throughput screening while comprehensive understanding the structure‐mechanism‐activity relationship. [ABSTRACT FROM AUTHOR]

Review: [51 refs. [ABSTRACT FROM AUTHOR]

Microstructure, texture and mechanical properties in the weld joint of variable polarity plasma arc welding of 5A06 Al alloy under the condition of non-axisymmetric arc have been investigated. The weld joint are characterized by elongated structure in the base material (BM), the heat affected zone (HAZ) and the transition zone (TZ) and equiaxed structure in the fusion zone (FZ). Microstructure of the weld joint is asymmetrical and inhomogeneous leading to deformation bands. Deformation texture and recrystallization texture were developed in the weld zones. The FZ center was dynamic recrystallized due to severe deformation. Materials in the TZ have undergone dynamic recovery. The weld zones are harder than the BM due to dislocation sub-structure, deformation bands and ultrafine subgrains. Microhardness distribution was homogeneous in the regions without deformation bands. Tensile fracture occurred along the deformation bands on the side of “lower arc” exhibiting ductile fracture, while the BM is less ductile. [ABSTRACT FROM AUTHOR]

The gradually increased concentration of carbon dioxide (CO2) in the atmosphere has been recognized as the primary culprit for the rise of the global mean temperature. In recent years, development of routes for highly efficient conversion of CO2 has received much attention. This Review describes recent progress on the design and synthesis of solid-state catalysts for the electrochemical reduction of CO2. The significance of this catalytic conversion is presented, followed by the general parameters for CO2 electroreduction and a summary of the reaction apparatus. We also discuss various types of solid catalysts based on their CO2 conversion mechanisms. We summarize the crucial factors (particle size, surface structure, composition, etc.) determining the performance for electroreduction. [ABSTRACT FROM AUTHOR]

Die allmählich zunehmende Konzentration an Kohlendioxid (CO2) in der Atmosphäre wurde als Hauptursache für den Anstieg der mittleren Erdtemperatur erkannt. In den letzten Jahren hat daher die Entwicklung von Wegen zur hocheffizienten Umwandlung von CO2 viel Beachtung gefunden. Dieser Aufsatz beschreibt neueste Fortschritte auf dem Gebiet von Festkörperkatalysatoren für die elektrochemische CO2‐Reduktion. Die Bedeutung dieser katalytischen Verfahren wird im Einführungsteil dargestellt, darauf folgen die allgemeinen Parameter für die elektrochemische CO2‐Reduktion und ein Überblick zur Reaktionsvorrichtung. Wir erörtern außerdem verschiedene Arten von festen Katalysatoren in Abhängigkeit von den Mechanismen der CO2‐Umwandlung. Darüber hinaus geben wir eine Zusammenfassung zu den entscheidenden Faktoren (Partikelgröße, Oberflächenstruktur, Zusammensetzung usw.), die die Leistungsfähigkeit der elektrochemischen Reduktion bestimmen. Die elektrochemische Reduktion von CO2 wird aufgrund der hohen Umweltverträglichkeit und der guten Kombinierbarkeit mit anderen erneuerbaren Energiequellen als wichtiger Weg für die CO2‐Umwandlung angesehen. Nanostrukturierte Materialien weisen eine hervorragende Leistung in der heterogenen elektrokatalytischen CO2‐Reduktion auf. Dieser Aufsatz beschreibt neueste Fortschritte bei diesen nanostrukturierten Katalysatoren. [ABSTRACT FROM AUTHOR]

Alloys are active in CO2 electroreduction due to their unique electronic and geometric structures. Nevertheless, CO2 reduction selectivity is still low due to the low concentration of CO2 near the catalyst surface and the high energy barrier for CO2 activation. This paper describes an AuCu nanochain aerogel (NC–AuCu) with abundant grain boundaries (GBs) that promote the accumulation and activation of CO2 for further electrochemical reduction, employing in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy and density functional theory calculations. GBs can induce a strong local electric field to concentrate the electrolyte cations and thus accumulate CO2 near the catalyst surface. NC–AuCu exhibits a superior Faradaic efficiency of close to 100% for CO2 electroreduction to CO at an extremely low overpotential of 110 mV with a high CO partial current density of 28.6 mA cm−2 in a flow cell. Coupling with a Si solar cell to convert solar energy to CO, a very high conversion efficiency of ∼13.0% is achieved. It potentially provides broad interest for further academic research and industry applications. [ABSTRACT FROM AUTHOR]

Review: 46 refs. [ABSTRACT FROM AUTHOR]

Review: 128 refs. [ABSTRACT FROM AUTHOR]