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Abstract The low-potential aldehyde oxidation reaction can occur at low potential (~0 VRHE) and release H2 at the anode, enabling hydrogen production with less than one-tenth of the energy consumption required for water splitting. Nevertheless, the activity and stability of Cu catalysts remain inadequate due to the oxidative deactivation of Cu-based materials. Herein, we elucidate the deactivation and reactivation cycle of Cu electrocatalyst and develop a self-reactivating PdCu catalyst that exhibits significantly enhanced stability. Initially, in-situ Raman spectroscopy confirm the cycle involved in electrochemical oxidation and non-electrochemical reduction. Subsequently, in-situ Raman spectroscopy and X-ray absorption fine structure reveal that the Pd component accelerates the rate of the non-electrochemical reduction, thereby enhancing the stability of the Cu-based electrocatalyst. Finally, a bipolar hydrogen production device is assembled utilizing the PdCu electrocatalyst, which can deliver a current of 400 mA cm−2 at 0.42 V and operate continuously for 120 h. This work offers guidance to enhance the stability of the Cu-based electrocatalyst in a bipolar hydrogen production system.

Abstract Currently, conventional dimethoxymethane synthesis methods are environmentally unfriendly. Here, we report a photo-redox catalysis system to generate dimethoxymethane using a silver and tungsten co-modified blue titanium dioxide catalyst (Ag.W-BTO) by coupling CO2 reduction and CH3OH oxidation under mild conditions. The Ag.W-BTO structure and its electron and hole transfer are comprehensively investigated by combining advanced characterizations and theoretical studies. Strikingly, Ag.W-BTO achieve a record photocatalytic activity of 5702.49 µmol g−1 with 92.08% dimethoxymethane selectivity in 9 h of ultraviolet-visible irradiation without sacrificial agents. Systematic isotope labeling experiments, in-situ diffuse reflectance infrared Fourier-transform analysis, and theoretical calculations reveal that the Ag and W species respectively catalyze CO2 conversion to *CH2O and CH3OH oxidation to *CH3O. Subsequently, an asymmetric carbon-oxygen coupling process between these two crucial intermediates produces dimethoxymethane. This work presents a CO2 photocatalytic reduction system for multi-carbon production to meet the objectives of sustainable economic development and carbon neutrality.

In this work, vanadium pentoxide (V2O5) and titanium-modified V2O5 thin films were synthesized using the sol-gel spin coating route. The effect of Ti-doping concentration on the electrochromic optical properties and atomic/electronic structures of V2O5 smart thin films is examined. As the doping concentration of Ti increases, the surface roughness of the films is reduced. The structure of the films is analyzed using X-ray diffraction (XRD) and Raman spectroscopy, while the electrochromic modulation of atomic and electronic structures is elucidated through Raman and X-ray absorption spectroscopy (XAS) conducted during lithiation and delithiation. The XRD patterns demonstrate that an increase in Ti concentration leads to a more amorphous structure of the films and a shift of the main diffraction peak to a lower angle, attributable to the enlarged spacing between the stacking layers resulting from the incorporation of Ti ions. Soft X-ray absorption spectroscopy (XAS) and in situ hard XAS of the V L-edge, the O K-edge, and the V K-edge revealed a reduction in the charge state of V and local atomic structural symmetry modification upon lithated coloration and delithiated bleaching process. The critical insights provided by in situ XAS provides reveal that a small amount of Ti has the ability to modify the interlayer distance and local atomic structure of V2O5, thereby improving its electrochromic switching rate and stability when utilized in smart windows.

Abstract Researchers are investigating innovative composite materials for renewable energy and energy storage systems. The major goals of this studies are i) to develop a low‐cost and stable trimetallic oxide catalyst and ii) to change the electrical environment of the active sites through site‐selective Mo substitution. The effect of Mo on NiCoMoO4 is elucidated using both in situ X‐ray absorption spectroscopy and X‐ray diffraction analysis. Also, density functional theory strategies show that NiCoMoO4 has extraordinary catalytic redox activity because of the high adsorption energy of the Mo atom on the active crystal plane. Further, it is demonstrated that hierarchical nanoflower structures of NiCoMoO4 on reduced graphene oxide can be employed as a powerful bifunctional electrocatalyst for oxygen reduction/evolution reactions in alkaline solutions, providing a small overpotential difference of 0.75 V. Also, Zn–air batteries based on the developed bifunctional electrocatalyst exhibit outstanding cycling stability and a high‐power density of 125.1 mW cm−2. This work encourages the use of Zn–air batteries in practical applications and provides an interesting concept for designing a bifunctional electrocatalyst.

In this work, the novel CuTa2O6 phase was successfully synthesized by the hydrothermal and followed by the calcination process. The X-ray diffraction pattern confirms the formation of different phases. At a low temperature, CuTa2O6 exhibits the orthorhombic phase, whereas, at a higher temperature, it underwent a phase transition to a cubic crystal structure. X-ray photoelectron spectroscopic results suggest the presence of all the elements (Cu, Ta, and O). The optical studies were carried out using a UV-Vis DRS spectrophotometer. FESEM images confirm the spherical-shaped particles for the sample annealed at a high temperature. The local atomic and electronic structures around Cu and the contribution of the Cu oxidation state in the CuTa2O6 system were determined by X-ray absorption spectroscopy. To investigate the effective usage of CuTa2O6 in treating wastewater, its photocatalytic activity was investigated by evaluating its use in the photodegradation of MO dye under visible light irradiation. Moreover, the prepared CuTa2O6 photocatalyst exhibits significant photocatalytic activity in the degradation of MO dye and shows excellent stability; it is therefore a promising material for potential use in a practical photocatalyst. The CuTa2O6 photocatalyst suggests an alternative avenue of research into effective photo-catalysts for solar hydrogen water splitting.

Bismuth vanadate (BiVO4) has attracted substantial attention on account of its usefulness in producing hydrogen by photoelectrochemical (PEC) water splitting. The exploitation of BiVO4 for this purpose is yet limited by severe charge recombination in the bulk of BiVO4, which is caused by the short diffusion length of the photoexcited charge carriers and inefficient charge separation. Enormous effort has been made to improve the photocurrent density and solar-to-hydrogen conversion efficiency of BiVO4. This study demonstrates that modulating the composition of the electrode and the electronic configuration of BiVO4 by decoration with silver nanoparticles (Ag NPs) is effective in not only enhancing the charge carrier concentration but also suppressing charge recombination in the solar water splitting process. Decoration with a small number of Ag NPs significantly enhances the photocurrent density of BiVO4 to an extent that increases with the concentration of the Ag NPs. At 0.5% Ag NPs, the photocurrent density approaches 4.1 mA cm−2 at 1.23 V versus a reversible hydrogen electrode (RHE) under solar simulated light illumination; this value is much higher than the 2.3 mA cm−2 of pure BiVO4 under the same conditions. X-ray absorption spectroscopy (XAS) is utilized to investigate the electronic structure of pure BiVO4 and its modification by decoration with Ag NPs. Analytical results indicate that increased distortion of the VO4 tetrahedra alters the V 3d–O 2p hybridized states. Additionally, as the Ag concentration increases, the oxygen vacancy defects that act as recombination centers in BiVO4 are reduced. In situ XAS, which is conducted under dark and solar illumination conditions, reveals that the significantly enhanced PEC performance is attributable to the synergy of modulated atomic/electronic structures and the localized surface plasmon resonance effect of the Ag nanoparticles.

Understanding of single-layer and bilayer thin films of WO3 and Ta2O5 for electrochromic applications remains elusive. In this study, single layers of WO3 and Ta2O5 and bilayer thin films of WO3/Ta2O5 and Ta2O5/WO3 were prepared by the sol–gel method followed by spin coating. X-ray diffraction (XRD) analysis revealed the semicrystalline nature of WO3 and the absence of significant crystalline planes in Ta2O5. Raman spectroscopy confirmed the characteristic vibrational modes of WO3 and Ta2O5 in both single-layer and bilayer thin films. Enhancement in cyclic voltammetry (CV) was observed in Ta2O5/WO3 compared to other thin films. Additionally, Ta2O5/WO3 exhibited a greater change in transmittance (ΔT) relative to other configurations. The impact of proton irradiation on the thin films was further investigated, revealing modifications in their structural and phonon vibrational properties. Notably, the CV performance of the irradiated thin films was drastically reduced. X-ray absorption spectroscopy (XAS) provided insights into the modulation of hybridization of O with W/Ta and the charge states of W and Ta in the thin films. This study provides a comprehensive understanding of single-layer and bilayer electrochromic thin films and their response to proton irradiation, paving the way for the development of space-applicable electrochromic bilayer thin films with improved performance and stability. [ABSTRACT FROM AUTHOR]

The rapid advancement of the hydrogen economy hinges on developing efficient systems that combine the sulfion oxidation reaction (SOR) and hydrogen evolution reaction (HER) to achieve cost-effective hydrogen production. Herein, a metal–organic framework derived Co3O4-integrated WS2 (CW) heterostructure with sulfur-rich vacancies was synthesized via a hydrothermal process. This ultrathin nanosheet structure afforded efficient electrocatalytic performance towards oxygen evolution reaction (OER), HER, and SOR by providing abundant active sites and optimal electronic configurations. The optimal CW heterostructure exhibited excellent OER and HER performance with lower overpotentials of 270 and 153 mV, respectively. The higher turnover frequency of the CW-2 electrocatalysts is 0.226 s−1 at the potential of 1.65 V. In situ/operando X-ray absorption spectroscopy (XAS) provided detailed insights into the dynamics at the catalyst surface and structural evolution under electrochemical conditions. In situ/operando XAS demonstrated a decrease in the coordination number of W–S when the applied potential was increased to 1.55 V due to the formation of sulfur vacancies. Sulfur and metal vacancies were plausibly co-existent, as demonstrated by the variation in the coordination number for the W–S first shell with the applied voltage, and the similar trend for the W–W second shell. Because of these advantages, the CW heterostructure exhibited better electrocatalytic activity for the OER, HER, and SOR. The assembled system with the CW-2 heterostructure established a remarkably low cell voltage of 0.41 V (@ 10 mA cm−2) for driving the cathodic HER and anodic SOR, with high faradaic efficiency (86.27%), and exceptional durability over 80 h. The findings of this study should contribute significantly to energy-efficient hydrogen production and sustainable sulfion recycling through the development of robust and highly effective catalysts. [ABSTRACT FROM AUTHOR]

The low-potential aldehyde oxidation reaction can occur at low potential (~0 VRHE) and release H2 at the anode, enabling hydrogen production with less than one-tenth of the energy consumption required for water splitting. Nevertheless, the activity and stability of Cu catalysts remain inadequate due to the oxidative deactivation of Cu-based materials. Herein, we elucidate the deactivation and reactivation cycle of Cu electrocatalyst and develop a self-reactivating PdCu catalyst that exhibits significantly enhanced stability. Initially, in-situ Raman spectroscopy confirm the cycle involved in electrochemical oxidation and non-electrochemical reduction. Subsequently, in-situ Raman spectroscopy and X-ray absorption fine structure reveal that the Pd component accelerates the rate of the non-electrochemical reduction, thereby enhancing the stability of the Cu-based electrocatalyst. Finally, a bipolar hydrogen production device is assembled utilizing the PdCu electrocatalyst, which can deliver a current of 400 mA cm−2 at 0.42 V and operate continuously for 120 h. This work offers guidance to enhance the stability of the Cu-based electrocatalyst in a bipolar hydrogen production system.A low-potential dual-side hydrogen production system is more efficient than water splitting but suffers from stability issues. Here, the authors report a self-reactivating PdCu catalyst that operates stably for 120 h, offering an alternative solution for energy-efficient hydrogen production. [ABSTRACT FROM AUTHOR]

MoSSe is a semiconducting material with a layered structure similar to MoS2 and MoSe2, which shows potential applications in optoelectronics, solar cells, sensing, and catalysis. Synthesis of this material with a controllable structure and chemical composition represents a great challenge. Herein, we report a new method for the synthesis of MoSSe by employing an [Et4N]2[Mo3S4Se3Br6] complex as the sole precursor. Thermal annealing of this complex under an Ar atmosphere at moderate temperatures ranging from 350 °C to 650 °C resulted in the formation of pure MoSSe. The morphology and structure of MoSSe were characterized using SEM, HRTEM, XRD, Raman spectroscopy, X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). The effects of annealing temperature on the structure of MoSSe were also examined. [ABSTRACT FROM AUTHOR]

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Currently, conventional dimethoxymethane synthesis methods are environmentally unfriendly. Here, we report a photo-redox catalysis system to generate dimethoxymethane using a silver and tungsten co-modified blue titanium dioxide catalyst (Ag.W-BTO) by coupling CO2 reduction and CH3OH oxidation under mild conditions. The Ag.W-BTO structure and its electron and hole transfer are comprehensively investigated by combining advanced characterizations and theoretical studies. Strikingly, Ag.W-BTO achieve a record photocatalytic activity of 5702.49 µmol g−1 with 92.08% dimethoxymethane selectivity in 9 h of ultraviolet-visible irradiation without sacrificial agents. Systematic isotope labeling experiments, in-situ diffuse reflectance infrared Fourier-transform analysis, and theoretical calculations reveal that the Ag and W species respectively catalyze CO2 conversion to *CH2O and CH3OH oxidation to *CH3O. Subsequently, an asymmetric carbon-oxygen coupling process between these two crucial intermediates produces dimethoxymethane. This work presents a CO2 photocatalytic reduction system for multi-carbon production to meet the objectives of sustainable economic development and carbon neutrality. This study unravels the efficient photocatalytic route for synthesizing dimethoxymethane by coupling CO2 reduction integrated with CH3OH oxidation by using a silver and tungsten comodified blue titanium dioxide catalyst under mild conditions. [ABSTRACT FROM AUTHOR]

Photocatalytic nanomaterials for indoor air purification have garnered attention for the removal of aromatic compounds, including toluene, among volatile organic compounds (VOCs). However, there are still limitations that need to be addressed for the practical implementation of this technology, such as low efficiency under indoor lighting and the stability of photocatalytic nanomaterials under real atmospheric conditions. In this study, we present an nanoscaled iron-decorated blue TiO2/WO3 Z-schemed catalyst that possesses the ideal band position for efficiently eliminating toluene. This catalyst generates reactive oxygen species, oxidizing toluene to benzaldehyde and ultimately converting it to CO2 under visible LED light. The toluene removal efficiency continuous flow reaction system is five times higher than that of each catalyst under a constant airflow system. The introduction of nanoscaled iron at the interface and on the surface between BTO and WO3 nanoparticles facilitates Z-scheme charge transfer, promoting the generation of reactive oxygen species (ROS) and effectively breaking down toluene via the Fenton reaction. The catalytic activity of BTO-Fe/WO3 is maintained at over 92% efficiency, even after three recycling cycles. This study demonstrates that the hybridization of nanoscaled iron and semiconductors can decompose the stable toluene ring even under an ambient visible light, showcasing practical performance for feasible air purification in a common indoor environment system. [ABSTRACT FROM AUTHOR]