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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]

Electrochemical formic acid oxidation reaction (FAOR) is a pivotal model for understanding organic fuel oxidation and advancing sustainable energy technologies. Here, we present mechanistic insights into a novel molecular‐like iridium catalyst (Ir−N4−C) for FAOR. Our studies reveal that isolated sites facilitate a preferential dehydrogenation pathway, circumventing catalyst poisoning and exhibiting high inherent activity. In situ spectroscopic analyses elucidate that weakly adsorbed intermediates mediate the FAOR and are dynamically regulated by potential‐dependent redox transitions. Theoretical and experimental investigations demonstrate a parallel mechanism involving two key intermediates with distinct pH and potential sensitivities. The rate‐determining step is identified as the adsorption of formate via coupled or sequential proton‐electron transfer, which aligns well with the observed kinetic properties, pH dependence, and hydrogen/deuterium isotope effects in experiments. These findings provide valuable insights into the reaction mechanism of FAOR, advancing our understanding at the molecular level and potentially guiding the design of efficient catalysts for fuel cells and electrolyzers. [ABSTRACT FROM AUTHOR]

Electrochemical water splitting is a pivotal process for sustainable hydrogen energy production, relying on efficient hydrogen evolution reaction (HER) catalysts, particularly in acidic environments, where both high activity and durability are crucial. Despite the favorable kinetics of platinum (Pt)‐based materials, their performance is hindered under harsh conditions, driving the search for alternatives. Due to their unique structural characteristic, Prussian blue analogs (PBAs) emerge as attractive candidates for designing efficient HER electrocatalysts. However, modulating their properties and functionalities is crucial to overcome their conductivity issue. Herein, a reconfiguration strategy for the dual‐driven surface restructuring of the CoFe PBA involving graphene quantum dots (GQD) and UV/ozone is proposed. X‐ray absorption spectroscopy (XAS) analysis revealed that dual‐driven reconstruction plays a pivotal role in promoting the high‐valence metal ions, effectively reducing charge transfer resistance—a key limitation in HER. The optimized CoFe PBA/GQD‐UV exhibits remarkable electrocatalytic performance toward HER, with a low overpotential of 77 mV to reach a current density of 10 mA cm−2 with excellent durability for 12 h under an extremely high current density of 500 mA cm−2 in an acidic solution. This dual‐combination strategy offering a new pathway to develop highly active electrocatalysts. [ABSTRACT FROM AUTHOR]

Delafossite AgFeO2 nanoparticles with a mixture of 2H and 3R phases were successfully fabricated by using a simple co-precipitation method. The resulting precursor was calcined at temperatures of 100, 200, 300, 400, and 500°C to obtain the delafossite AgFeO2 phase. The morphology and microstructure of the prepared AgFeO2 samples were characterized by using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), N2 adsorption/desorption, X-ray absorption spectroscopy (XAS), and X-ray photoelectron spectroscopy (XPS) techniques. A three-electrode system was employed to investigate the electrochemical properties of the delafossite AgFeO2 nanoparticles in a 3 M KOH electrolyte. The delafossite AgFeO2 nanoparticles calcined at 100°C (AFO100) exhibited the highest surface area of 28.02 m2·g−1 and outstanding electrochemical performance with specific capacitances of 229.71 F·g−1 at a current density of 1 A·g−1 and 358.32 F·g−1 at a scan rate of 2 mV·s−1. This sample also demonstrated the capacitance retention of 82.99% after 1000 charge/discharge cycles, along with superior specific power and specific energy values of 797.46 W·kg−1 and 72.74 Wh·kg−1, respectively. These findings indicate that delafossite AgFeO2 has great potential as an electrode material for supercapacitor applications. [ABSTRACT FROM AUTHOR]

Molybdenum (Mo) is an essential micronutrient for plants, yet it also poses potential environmental risks when present in excess. This study investigated the Mo speciation in soils with varying properties and their influences on Mo uptake by wheat (Triticum aestivum L.), a staple crop with significant implications for global food security. Mo K-edge X-ray absorption spectroscopy (XAS), combined with a sequential extraction method, was employed to analyze the chemical speciation and fractionation of Mo in the soils before and after wheat cultivation. The predominant Mo species identified were sorbed molybdate (Mo(VI)) and Ca- and Fe-Mo(VI) precipitates. After wheat cultivation, sorbed Mo(VI) and Ca-Mo(VI) decreased while Fe-Mo(VI) increased, with the most notable changes observed in the alkaline soil. These changes indicated that the desorption of sorbed Mo(VI) and dissolution of Ca-Mo(VI) contributed to soil Mo availability, while Fe-Mo(VI) precipitation restricted it. Bioaccumulation and translocation factors revealed efficient Mo uptake and transport within wheat plants, with shoots being the primary site of Mo accumulation. Elevated Mo concentrations in wheat grains raise potential human health concerns due to dietary exposure. These findings underscore the critical role of soil Mo speciation in controlling Mo dynamics in soil-wheat systems, providing valuable insights for managing Mo in agricultural soils to balance its nutritional benefits with the risks of excessive crop accumulation., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Shan-Li Wang reports financial support was provided by National Science and Technology Council, Taiwan (ROC). If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 Elsevier Ltd. All rights reserved.)

From a comparison of the known molecular stoichiometry and X-ray photoemission spectroscopy (XPS), it is evident that the Fe(III) spin crossover salt [Fe(qsal)2Ni(dmit)2], where qsal = N(8quinolyl)salicylaldimine, and dmit2- = 1,3-dithiol-2-thione-4,5-dithiolato has a preferential surface termination with the Ni(dmit)2 moiety. This preferential surface termination leads to a significant surface to bulk core level shift for the Ni 2p X-ray photoemission core level, not seen in the corresponding Fe 2p core level spectra. A similar surface to bulk core level shift is seen in Pd 3d in the related [Fe(qsal)2]2Pd(dmit)2, ], where qsal = N(8quinolyl)salicylaldimine, and dmit2- = 1,3-dithiol-2-thione-4,5-dithiolato. Inverse photoemission spectroscopy (IPES), compared with the X-ray absorption spectra at the Ni-L3,2 edge provides some indication of the density of states resulting from the dmit2- = 1,3-dithiol-2-thione-4,5-dithiolato ligand unoccupied molecular orbitals and thus supports the evidence regarding surface termination in the Ni(dmit)2 moiety., (Creative Commons Attribution license.)

In the frame of developing a sustainable chemical industry, heterogeneously catalyzed CO2 hydrogenation to methanol has attracted considerable interest. However, the Cu-Zn based catalyst system employed in this process is very dynamic, especially in the presence of the products methanol and water. Deactivation needs to be prevented, but its origin and mechanism are hardly investigated at high conversion where product condensation is possible. Here, we report on the structural dynamics of a Cu/ZnO/ZrO2 catalyst at 90 bar and 40% CO2 conversion (at equilibrium conditions), investigated in a dedicated metal-based spectroscopic cell specially fabricated using additive manufacturing. This particular reactor configuration aims to mimic the high CO2 conversion part of the catalyst bed and can induce product condensation, which is monitored by operando X-ray absorption spectroscopy. While Cu remained mostly stable throughout the experiment, Zn underwent strong restructuring. The chosen reaction conditions, including the use of CO2 as carbon source and in situ product condensation, were selected to provide insights under industrial conditions. This work highlights the importance of spectroscopic investigations at high conversion levels, offering insights into chemical transformations during deactivation, extending the concept of spatially resolved studies, and thus providing guidance for the design of more stable catalysts., (© 2025 Wiley‐VCH GmbH.)

Combining operando X-ray absorption spectroscopy (XAS) and computational modelling shows unequivocally the distribution of active species in fresh and hydrothermally aged Cu-CHA and Cu-AEI zeolites during NH 3 -assisted selective catalytic reduction of NO x . Four principal species co-exist: (i) Cu I cations coordinated to NH 3 , (ii) Cu I cations coordinated to the zeolite framework, (iii) solvated Cu II cations, and (iv) framework-coordinated Cu II species (Cu II st ) formed upon hydrothermal ageing of the zeolite sample. The Cu II st species were only observed in the hydrothermally aged zeolite samples and are formed upon the interaction of hydrated Cu II cations with extra-framework Al (EFAl) generated during the hydrothermal treatment. These sites are inactive for NO x reduction, leading to a decrease in the catalytic performance of the hydrothermally aged zeolites. Cu II st formation was higher in Cu-CHA (~46 %) than in Cu-AEI (~28 %). The better hydrothermal stability of Cu in the AEI framework is attributed to the tortuous channel structure of AEI that hinders the migration of hydrated Cu II cations during hydrothermal ageing., (© 2024 The Author(s). Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Rechargeable batteries are central to modern energy storage systems, from portable electronics to electric vehicles. The cathode material, a critical component, largely dictates a battery's energy density, capacity, and overall performance. This review focuses on the application of operando X-ray absorption spectroscopy (XAS) to study cathode materials in Li-ion, Na-ion, Li-S, and Na-S batteries. Operando XAS provides real-time insights into the local electronic structure, oxidation states, and coordination environments, which are crucial for understanding complex electrochemical processes, such as redox reactions, phase transitions, and structural degradation. The review highlights the strengths of hard and soft XAS techniques in probing transition metal (TM) and anionic redox processes, particularly in layered oxide cathodes, where reversible oxygen redox and TM behavior are pivotal. The role of operando XAS is also explored in analyzing conversion-type S-based cathodes, where it helps unravel the intricate reaction mechanisms. Furthermore, the review addresses the challenges of in situ cell design for operando XAS, especially under ultrahigh vacuum conditions for soft XAS. By discussing recent advancements and future directions, this review underscores the critical role of operando XAS in driving innovation and improving the design and performance of next-generation battery technologies., (© 2025 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

Alkane monooxygenase (AlkB) is the dominant enzyme that catalyzes the oxidation of liquid alkanes in the environment. Two recent structural models derived from cryo-electron microscopy (cryo-EM) reveal an unusual active site: a histidine-rich center that binds two iron ions without a bridging ligand. To ensure that potential photoreduction and radiation damage are not responsible for the absence of a bridging ligand in the cryo-EM structures, spectroscopic methods are needed. We present the results of extended X-ray absorption fine structure (EXAFS) experiments collected under conditions where photodamage was avoided. Careful data analysis reveals an active site structure consistent with the cryo-EM structures in which the two iron ions are ligated by nine histidines and separated by at least 5 Å. The EXAFS data were used to inform structural models for molecular dynamics (MD) simulations. The MD simulations corroborate EXAFS observations that neither of the two conserved carboxylate-containing residues (E281 and D190) near the active site are likely candidates for metal ion bridging. Mutagenesis experiments, spectroscopy, and additional MD simulations were used to further explore the role of these carboxylate residues. A variant in which a carboxylate containing residue (E281) was changed to a methyl residue (E281A) showed little change in pre-edge features, consistent with the observation that it is not essential for activity and hence unlikely to serve as a bridging ligand at any point in the catalytic cycle. D190 variants had substantially diminished activity, suggesting an important role in catalysis not yet fully understood.

This work aims to deal with the challenges associated with designing complementary bifunctional electrocatalysts and a separator/membrane that enables rechargeable zinc-air batteries (RZABs) with nearly solid-state operability. This solid-state RZAB was accomplished by integrating a bifunctional electrocatalyst based on Ru-RuO 2 interface nanoparticles supported on nitrogen-doped (N-doped) graphene (Ru-RuO 2 /NGr) and a dual-doped poly(acrylic acid) hydrogel (d-PAA) electrolyte soaked in KOH with sodium stannate additive. The catalyst shows enhanced activity and stability toward the two oxygen reactions, i.e., oxygen reduction and evolution reactions (ORR and OER), with a very low potential difference (Δ E ) of 0.64 V. The computational insights bring out the electronic factors contributing to the enhanced catalytic activity of Ru-RuO 2 /NGr based on the charge density difference (CDD) between the interfaces. The disadvantages of the existing solid-state RZABs, such as their limited lifespan brought on by passivation, dendritic growth, corrosion, and shape change, have also been taken into account. The introduction of the stannate additive to the electrolyte induced an in situ Zn-anode modification, which subsequently improved the interfacial stability of the ZABs and, hence, the battery life cycles. The experimental observations reveal that, during the charging process, the Sn nanoparticles enable the homogeneous Zn deposition on the surface of the anode. Thus, the in situ Zn-anode surface modification assisted in achieving a high-rate cycle capability, viz., the homemade catalyst-based system exhibited continuous charge-discharge cycles for 20 h at a current density of 2.0 mA cm -2 , with each cycle lasting for 5 min.

This study investigated the speciation and aqueous dissolution of macronutrients in fire ash from diverse ecosystems and speciation of ash and smoke from laboratory burning, exploring the variations and their causes. The speciation of phosphorus (P), calcium (Ca), and potassium (K) in fire ash from five globally distributed ecosystems was characterized by using X-ray absorption spectroscopy and sequential fractionation. Aqueous dissolution of the macronutrients was measured by batch experiments at acidic and alkaline pHs. The results showed that P existed mainly as Ca phosphates, Ca as double carbonates, calcite, and sulfates, and most K was associated with Ca carbonates. Mineralogy and the relative abundance of the species were primarily controlled by elemental stoichiometry and fire temperature. Differences in Ca and P speciation existed between ash and smoke from laboratory burning, possibly caused by the temperature difference and/or mass fractionation during burning. The rates, extents, and pH dependencies of macronutrient dissolution differed among macronutrients and depended on their speciation, with K being highly soluble and the P and Ca regulated by solution pH. The variability in ash macronutrient chemistry and ecosystem-specific fire ash loads resulted in varying loads and availability of individual macronutrient from fire among ecosystems. This study provides a mechanistic understanding of how fires transform the chemistry of macronutrients and affect macronutrient returns to soils across different ecosystems, which is essential for evaluating the disturbance to ecosystem nutrient cycling by fires.

Single-atom catalysts (SACs) are gathering significant attention in chemistry due to their unique properties, offering uniform active site distribution and enhanced selectivity. However, their precise structure often remains unclear, with multiple models proposed in the literature. Understanding the coordination environment of the active site at the atomic level is crucial for explaining catalytic activity. Here, a comprehensive study of SACs made of carbon nitride (CN x ) containing isolated nickel atoms is presented. Using a combination of synthesis techniques and characterization methods including Fourier-transform infrared spectroscopy, X-ray absorption spectroscopy (XAS), and density functional theory (DFT) calculations, the local environment of nickel active centers in CN x -supported SACs is investigated. These results challenge conventional structural models and propose a new architecture that better aligns with current experimental evidence. This new structure serves as a foundational step toward a rational approach to catalyst development and can facilitate more precise design and application of these innovative catalysts., (© 2025 The Author(s). Small published by Wiley‐VCH GmbH.)

Manganese oxide-based filtration technologies are considered cost-effective for thallium (Tl) removal in engineered systems. However, current gaps in understanding the heterogeneous adsorption and oxidation mechanisms of typical tunneled α-MnO 2 may lead to a serious underestimation of its long-term Tl removal potential. In this study, α-MnO 2 could continuously remove Tl(I) during the 584-h reaction, with its irreversible removal eventually increasing to 81 %-95 % in different anionic environments. The adsorbed low-loaded Tl(I) is preferentially oxidized, whereas the high-loaded Tl tends to be adsorbed in a nonoxidative pathway by α-MnO 2 . The nonoxidized Tl(I) was gradually immobilized in the stable thalliomelane-like tunnel structure. More importantly, the synergism of surface Mn(III)-oxygen vacancies (O v ) on α-MnO 2 could catalyze the oxidation of Tl(I). Furthermore, the oxidized Tl(III) was bound to the tunnel surface via double edge-sharing and double corner-sharing. In addition, the phosphate anion occupied the surface active site and inhibited the oxidation of Tl(I), thereby reducing the binding strength of Tl. This study provides a new perspective on the effectiveness and stability of Tl(I) removal by MnO 2 and highlights the neglected mechanism of Mn(III)-O v mediating Tl(I) oxidation, which expands our understanding of the removal and transformation fate of Tl in MnO 2 -engineered systems., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 Elsevier B.V. All rights reserved.)

Stable Sb exhibits a rhombohedral structure, often referred to as distorted primitive cubic, with each Sb atom having three short and three longer first neighbor bonds. However, this crystal structure can also be interpreted as being layered, putting emphasis on only three short first neighbor bonds. Therefore, temperature-dependent extended X-ray absorption fine structure (EXAFS) spectroscopy is carried out at the Sb K-edge in order to obtain more detailed information on local structural and vibrational properties. Evaluation of the temperature-dependent bond lengths provides the temperature-dependent Peierls distortion while the temperature dependence of the variance of the interatomic distance distribution yields the EXAFS force constants. Ab initio density functional theory (DFT) calculations are used for determining projected force constants. Both EXAFS and DFT force constants are compared to those of other materials with different bonding characteristics, including two-center covalently bonded semiconductors, multicenter bonded IV-VI and V 2 VI 3 compounds, and metallic Cu. Clearly, Sb exhibits characteristics of both localized covalent bonding and delocalized multicenter bonding. This suggests a continuous transition between these two bonding scenarios and adds to the understanding of bonding in elemental Sb in particular and in IV-VI and V 2 VI 3 materials in general., (© 2025 The Author(s). Advanced Materials published by Wiley‐VCH GmbH.)

Crystal facet engineering has emerged as a promising approach to enhance photocatalytic activity of semiconductors by preferentially accumulating charge carriers (electrons and holes) on specific facets. This facilitates efficient electron and hole transfer across the semiconductor/cocatalyst interface, enabling their transport to the cocatalyst surface for redox reactions. In this study, three Cu-doped TiO 2 nanorods with small, medium, and large ratios of reductive {110} to oxidative {111} facets were synthesized (namely Cu-TiO 2 -SR, Cu-TiO 2 -MR, and Cu-TiO 2 -LR, respectively). These materials were comparatively evaluated for the inactivation of phiX174 bacteriophage under visible light illumination. Notably, Cu-TiO 2 -LR demonstrated an outstanding inactivation rate of phiX174 (0.42 log inactivation/min), approximately 11.8 times higher than that of Cu-TiO 2 -SR. Photo- and electrochemical analyses revealed that Cu-TiO 2 -LR exhibited superior electron/hole separation efficiency, leading to enhanced Cu redox reactions. Various experiments, encompassing viral inactivation tests with different additives, protein oxidation assays, and DNA damage assessments, indicated that Cu(III) is the major virucidal species responsible for the phiX174 inactivation by illuminated Cu-TiO 2 -LR. Under visible light illumination, Cu-TiO 2 -LR also showed excellent reusability and minimal activity loss in the presence of humic acid and inorganic anions, as well as general microbicidal effects on other viral and bacterial species., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)