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Single-atom catalysts dispersed on an oxide support are essential for overcoming the sluggishness of the oxygen evolution reaction (OER). However, the durability of most metal single-atoms is compromised under harsh OER conditions due to their low coordination (weak metal-support interactions) and excessive disruption of metal-O lattice bonds to enable lattice oxygen participation, leading to metal dissolution and hindering their practical applicability. Herein, we systematically regulate the local coordination of Ir single-atoms at the atomic level to enhance the performance of the OER by precisely modulating their steric localization on the NiO surface. Compared to conventional Ir single-atoms adsorbed on NiO surface, the atomic Ir atoms partially embedded within the NiO surface (Ir emb -NiO) exhibit a 2-fold increase in Ir-Ni second-shell interaction revealed by X-ray absorption spectroscopy (XAS), suggesting stronger metal-support interactions. Remarkably, Ir emb -NiO with tailored coordination sphere exhibits excellent alkaline OER mass activity and long-term durability (degradation rate: ∼1 mV/h), outperforming commercial IrO 2 (∼26 mV/h) and conventional Ir single-atoms on NiO (∼7 mV/h). Comprehensive operando X-ray absorption and Raman spectroscopies, along with pH-dependence activity tests, identified high-valence atomic Ir sites embedded on the NiOOH surface during the OER followed the lattice oxygen mechanism, thereby circumventing the traditional linear scaling relationships. Moreover, the enhanced Ir-Ni second-shell interaction in Ir emb -NiO plays a crucial role in imparting structural rigidity to Ir single-atoms, thereby mitigating Ir-dissolution and ensuring superior OER kinetics alongside sustained durability.

Exploring single-atom-catalysts for the acidic oxygen evolution reaction (OER) is of paramount importance for cost-effective hydrogen production via acidic water electrolyzers. However, the limited durability of most single-atom-catalysts and Ir/Ru-based oxides under harsh acidic OER conditions, primarily attributed to excessive lattice oxygen participation resulting in metal-leaching and structural collapse, hinders their practical application. Herein, an innovative strategy is developed to fabricate short-range Ir single-atom-ensembles (Ir SAE ) stabilized on the surface of Mn-substituted spinel Co 3 O 4 (Ir SAE -CMO), which exhibits excellent mass activity and significantly improved durability (degradation-rate: ≈2 mV h -1 ), outperforming benchmark IrO 2 (≈44 mV h -1 ) and conventional Ir single-atoms on pristine-Co 3 O 4 for acidic OER. First-principle calculations reveal that Mn-substitution in the octahedral sites of Co 3 O 4 substantially reduces the migration energy barrier for Ir single-atoms on the CMO surface compared to pristine-Co 3 O 4 , facilitating the migration of Ir single-atoms to form strongly correlated Ir SAE during pyrolysis. Extensive ex situ characterization, operando X-ray absorption and Raman spectroscopies, pH-dependence activity tests, and theoretical calculations indicate that the rigid Ir SAE with appropriate Ir-Ir distance stabilized on the CMO surface effectively suppresses lattice oxygen participation while promoting direct O─O radical coupling, thereby mitigating Ir-dissolution and structural collapse, boosting the stability in an acidic environment., (© 2024 The Author(s). Advanced Materials published by Wiley‐VCH GmbH.)

ConspectusThe study of the origin of life requires a multifaceted approach to understanding where and how life arose on Earth. One of the most compelling hypotheses is the chemosynthetic origin of life at hydrothermal vents, as this condition has been considered viable for early forms of life. The continuous production of H 2 and heat by serpentinization generates reductive conditions at hydrothermal vents, in which CO 2 can be used to build large biomolecules. Although this involves surface catalysis and an autocatalytic process, in which solid minerals act as catalysts in the conversion of CO 2 to metabolically important organic molecules, the systematic investigation of heterogeneous catalysis to comprehend prebiotic chemistry at hydrothermal vents has not been undertaken.In this Account, we discuss geochemical CO 2 fixation to metabolic intermediates by synthetic minerals at hydrothermal vents from the perspective of heterogeneous catalysis. Ni and Fe are the most abundant transition metals at hydrothermal vents and occur in the active site of the enzymes carbon monoxide dehydrogenases/acetyl coenzyme A synthases (CODH/ACS). Synthetic free-standing NiFe alloy nanoparticles can convert CO 2 to acetyl coenzyme A pathway intermediates such as formate, acetate, and pyruvate. The same alloy can further convert pyruvate to citramalate, which is essential in the biological citramalate pathway. Thermal treatment of Ni 3 Fe nanoparticles under NH 3 , which can occur in hydrothermal vents, results in Ni 3 FeN/Ni 3 Fe heterostructures. This catalyst has been demonstrated to produce prebiotic formamide and acetamide from CO 2 and H 2 O using Ni 3 FeN/Ni 3 Fe as both substrate and catalyst. In the process of serpentinization, Co can be reduced in the vicinity of olivine, a Mg-Fe silicate mineral. This produces CoFe and CoFe 2 with serpentine in nature, representing SiO 2 -supported CoFe alloys. In mimicking these natural minerals, synthetic SiO 2 -supported CoFe alloys demonstrate the same liquid products as NiFe alloys, namely, formate, acetate, and pyruvate under mild hydrothermal vent conditions. In contrast to the NiFe system, hydrocarbons up to C 6 were detected in the gas phase, which is also present in hydrothermal vents. The addition of alkali and alkaline-earth metals to the catalysts results in enhanced formate concentration, playing a promotional role in CO 2 reduction. Finally, Co was loaded onto ordered mesoporous SiO 2 after modification with cations to simulate the minerals found in hydrothermal vents. These catalysts were then investigated under diminished H 2 O concentration, revealing the conversion of CO 2 to CO, CH 4 , methanol, and acetate. Notably, the selectivity to metabolically relevant methanol was enhanced in the presence of cations that could generate and stabilize the methoxy intermediate. Calculation using the machine learning approach revealed the possibility of predicting the selectivity of CO 2 fixation when modifying mesoporous SiO 2 supports with heterocations. Our research demonstrates that minerals at hydrothermal vents can convert CO 2 into metabolites under a variety of prebiotic conditions, potentially paving the way for modern biological CO 2 fixation processes.

The selective oxidative coupling of phenol derivatives, involving carbon-carbon (C-C) and carbon-oxygen (C-O) bond formation, has emerged as a critical approach in the synthesis of natural products. However, achieving precise control over the selectivity in coupling reactions of unsubstituted phenols utilizing solar light as the driving force remains a big challenge. In this study, we report a series of porous Cs 3 Bi 2 X 9 (X=Cl, Br, I) photocatalysts with tailored band gaps and compositions engineered for efficient solar-light-driven oxidative phenol coupling. Notably, p-Cs 3 Bi 2 Br 9 exhibited about 73 % selectivity for C-C coupling, displaying a high formation rate of 47.3 μmol g cat  h -1  h -1 under solar radiation. Furthermore, this approach enables control of the site-selectivity for phenol derivatives on Cs 3 Bi 2 X 9 , enhancing C-C coupling. The distinctive porous structure and appropriate band-edge positions of Cs 3 Bi 2 Br 9 facilitated efficient charge separation, and surface interaction/activation of phenolic hydroxyl groups, resulting in the kinetically preferred formation of C-C over C-O bond. Mechanistic insights into the reaction pathway, supported by comprehensive control experiments, unveiled the crucial role of interfacial charge transfers and Lewis acid Bi sites in stabilizing phenolic intermediates, thereby directing the regioselectivity of diradical couplings and resulting in the formation of unsymmetrical biphenols., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Niobium oxide (Nb 2 O 5 ) is a versatile semiconductor material with photochromic properties. This study investigates the local structure of noncrystalline, short-range-ordered niobium oxide synthesized via a sol-gel method. X-ray atomic pair distribution function analysis unravels the structural arrangements within the noncrystalline materials at a local scale. In the following, in situ scattering and diffraction experiments elucidate the heat-induced structure transformation of the amorphous material into crystalline TT-Nb 2 O 5 at 550 °C. In addition, the effect of photocatalytic conditions on the structure of the material was investigated by exposing the short-range-ordered and crystalline materials to ultraviolet light, resulting in a reversible color change from white to dark brown or blue. This photochromic response is due to the reversible elongation of the nearest Nb-O neighbors, as shown by local structure analysis based on in situ PDF analyses. Optical band gap calculations based on the ultraviolet-visible spectra collected for both the short-range-ordered and crystalline materials show that the band gap values reduced for the darkened materials return to their initial state after bleaching. Furthermore, electron energy loss spectroscopy reveals the reduction of Nb 5+ to Nb 4+ centers as a persistent effect. The study establishes a correlation between the band gap and the structure of niobium oxide, providing insights into the structure-performance relation at the atomic level.

Hydrogen (H 2 ) has powered microbial metabolism for roughly 4 billion years. The recent discovery that it also fuels geochemical analogs of the most ancient biological carbon fixation pathway sheds light on the origin of metabolism. However, it remains unclear whether H 2 can sustain more complex nonenzymatic reaction networks. Here, we show that H 2 drives the nonenzymatic reductive amination of six biological ketoacids and glyoxylate to give the corresponding amino acids in good yields using ammonium concentrations ranging from 6 to 150 mM. Catalytic amounts of nickel or ground meteorites enable these reactions at 22°C and pH 8. The same conditions promote an H 2 -dependent ketoacid-forming reductive aldol chemistry that co-occurs with reductive amination, producing a continuous reaction network resembling amino acid synthesis in the metabolic core of ancient microbes. The results support the hypothesis that the earliest biochemical networks could have emerged without enzymes or RNA., Competing Interests: Declaration of Interests The authors declare no competing interests.

Autotrophic theories for the origin of metabolism posit that the first cells satisfied their carbon needs from CO 2 and were chemolithoautotrophs that obtained their energy and electrons from H 2 . The acetyl-CoA pathway of CO 2 fixation is central to that view because of its antiquity: Among known CO 2 fixing pathways it is the only one that is i) exergonic, ii) occurs in both bacteria and archaea, and iii) can be functionally replaced in full by single transition metal catalysts in vitro. In order to operate in cells at a pH close to 7, however, the acetyl-CoA pathway requires complex multi-enzyme systems capable of flavin-based electron bifurcation that reduce low potential ferredoxin-the physiological donor of electrons in the acetyl-CoA pathway-with electrons from H 2 . How can the acetyl-CoA pathway be primordial if it requires flavin-based electron bifurcation? Here, we show that native iron (Fe 0 ), but not Ni 0 , Co 0 , Mo 0 , NiFe, Ni 2 Fe, Ni 3 Fe, or Fe 3 O 4 , promotes the H 2 -dependent reduction of aqueous Clostridium pasteurianum ferredoxin at pH 8.5 or higher within a few hours at 40 °C, providing the physiological function of flavin-based electron bifurcation, but without the help of enzymes or organic redox cofactors. H 2 -dependent ferredoxin reduction by iron ties primordial ferredoxin reduction and early metabolic evolution to a chemical process in the Earth's crust promoted by solid-state iron, a metal that is still deposited in serpentinizing hydrothermal vents today., Competing Interests: Competing interests statement:The authors declare no competing interest.

To test the ability of geochemical surfaces in serpentinizing hydrothermal systems to catalyze reactions from which metabolism arose, we investigated H 2 -dependent CO 2 reduction toward metabolic intermediates over silica-supported Co-Fe catalysts. Supported catalysts converted CO 2 to various products at 180 °C and 2.0 MPa. The liquid product phase included formate, acetate, and ethanol, while the gaseous product phase consisted of CH 4 , CO, methanol, and C 2 -C 7 linear hydrocarbons. The 1/1 ratio CoFe alloy with the same composition as the natural mineral wairauite yielded the highest concentrations of formate (6.0 mM) and acetate (0.8 mM), which are key intermediates in the acetyl-coenzyme A (acetyl-CoA) pathway of CO 2 fixation. While Co-rich catalysts were proficient at hydrogenation, yielding mostly CH 4 , Fe-rich catalysts favored the formation of CO and methanol. Mechanistic studies indicated intermediate hydrogenation and C-C coupling activities of alloyed CoFe, in contrast to physical mixtures of both metals. Co in the active site of Co-Fe catalysts performed a similar reaction as tetrapyrrole-coordinated Co in the corrinoid iron-sulfur (CoFeS) methyl transferase in the acetyl-CoA pathway. In a temperature range characteristic for deeper regions of serpentinizing systems, oxygenate product formation was favored at lower, more biocompatible temperatures., Competing Interests: Conflict of Interests The authors declare no conflict of interest.

Designing materials for catalysis is challenging because the performance is governed by an intricate interplay of various multiscale phenomena, such as the chemical reactions on surfaces and the materials' restructuring during the catalytic process. In the case of supported catalysts, the role of the support material can be also crucial. Here, we address this intricacy challenge by a symbolic-regression artificial intelligence (AI) approach. We identify the key physicochemical parameters correlated with the measured performance, out of many offered candidate parameters characterizing the materials, reaction environment, and possibly relevant underlying phenomena. Importantly, these parameters are obtained by both experiments and ab initio simulations. The identified key parameters might be called "materials genes", in analogy to genes in biology: they correlate with the property or function of interest, but the explicit physical relationship is not (necessarily) known. To demonstrate the approach, we investigate the CO 2 hydrogenation catalyzed by cobalt nanoparticles supported on silica. Crucially, the silica support is modified with the additive metals magnesium, calcium, titanium, aluminum, or zirconium, which results in six materials with significantly different performances. These systems mimic hydrothermal vents, which might have produced the first organic molecules on Earth. The key parameters correlated with the CH 3 OH selectivity reflect the reducibility of cobalt species, the adsorption strength of reaction intermediates, and the chemical nature of the additive metal. By using an AI model trained on basic elemental properties of the additive metals (e.g., ionization potential) as physicochemical parameters, new additives are suggested. The predicted CH 3 OH selectivity of cobalt catalysts supported on silica modified with vanadium and zinc is confirmed by new experiments.

Hydrothermal vents harbor numerous microbial communities rich in reduced carbon species such as formate, acetate, and hydrocarbons. Such essential chemicals for life are produced by H 2 -dependent CO 2 reduction, where serpentinization provides continuous H 2 and thermal energy. Here, we show that silica-supported bimetallic Co-Fe alloys, naturally occurring minerals around serpentinite, can convert CO 2 and H 2 O to key metabolic intermediates of the acetyl coenzyme A pathway such as formate (up to 72 mM), acetate, and pyruvate under mild hydrothermal vent conditions. Long-chain hydrocarbons up to C 6 including propene are also detected, just as in the Lost City hydrothermal field. The effects of promoters on structural properties and catalytic functionalities of the Co-Fe alloy are systematically investigated by incorporating a series of alkali and alkaline earth metals including Na, Mg, K, and Ca. Alkali and alkaline earth metals resulted in higher formate concentrations when dissolved in water and increased reaction pH, while alkaline earth metals also favored the formation of insoluble hydroxides and carbonates similar to the constituent minerals of the chimneys at the Lost City hydrothermal fields., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

ConspectusThe global energy landscape is undergoing significant change. Hydrogen is seen as the energy carrier of the future and will be a key element in the development of more sustainable industry and society. However, hydrogen is currently produced mainly from fossil fuels, and this needs to change. Alkaline water electrolysis with advanced technology has the most significant potential for this transition to produce large-scale green hydrogen by utilizing renewable energy. The assembly of industrial electrolyzer plants is more complex on a larger scale, but it follows a basic working principle, which involves two half-cells of anode and cathode sites where the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) occur. Out of the two reactions, the OER is more challenging both thermodynamically and kinetically. Besides having access to renewable electricity, developing durable and abundant electrocatalysts for the OER remains a challenge in large-scale alkaline water electrolysis. Among different physicochemical properties, the electrocatalyst surface and its interaction with water and reaction intermediates, as well as formed molecular hydrogen and oxygen, play an essential role in the catalytic performance and the reaction mechanism. In particular, the binding strengths between the catalyst surface and intermediates determine the rate-limiting step and electrocatalytic performance.This Account gives some insights into the status of the hydrogen economy and basic principles of alkaline water electrolysis by covering its fundamentals as well as industrial developments. Further, the HER and OER reaction mechanisms of alkaline water electrolysis and selected electrocatalyst progress for both half-reactions are briefly discussed. The Adsorbate Evolution Mechanism and the Lattice Oxygen Mechanism for the OER are explained with specific references. This Account also deliberates on the author's selected contributions to the development of transition metal-based electrocatalysts for alkaline water electrolysis with an emphasis on OER. The focus is particularly given to the enhancement of intrinsic activity, the role of e g -filling, phase segregation, and defect structure of cobalt-based electrocatalysts for OER. Structural modification and phase transformation of the cobalt oxide electrocatalyst under working conditions are further deliberated. In addition, the creation of new active surface species and the activation of cobalt- and nickel-based electrocatalysts through iron uptake from the alkaline electrolyte are discussed. In the end, this Account provides a brief overview of challenges related to large-scale production and utilization of green hydrogen.

Formamide can serve as a key building block for the synthesis of organic molecules relevant to premetabolic processes. Natural pathways for its synthesis from CO 2 under early earth conditions are lacking. Here, we report the thermocatalytic conversion of CO 2 and H 2 O to formate and formamide over Ni-Fe nitride heterostructures in the absence of synthetic H 2 and N 2 under mild hydrothermal conditions. While water molecules act as both a solvent and hydrogen source, metal nitrides serve as nitrogen sources to produce formamide in the temperature range of 25-100 °C under 5-50 bar. Longer reaction times promote the C-C bond coupling and formation of acetate and acetamide as additional products. Besides liquid products, methane and ethane are also produced as gas-phase products. Postreaction characterization of Ni-Fe nitride particles reveals structural alteration and provides insights into the potential reaction mechanism. The findings indicate that gaseous CO 2 can serve as a carbon source for the formation of C-N bonds in formamide and acetamide over the Ni-Fe nitride heterostructure under simulated hydrothermal vent conditions.

Abiotic synthesis of formate and short hydrocarbons takes place in serpentinizing vents where some members of vent microbial communities live on abiotic formate as their main carbon source. To better understand the catalytic properties of Ni-Fe minerals that naturally exist in hydrothermal vents, we have investigated the ability of synthetic Ni-Fe based nanoparticular solids to catalyze the H 2 -dependent reduction of CO 2 , the first step required for the beginning of pre-biotic chemistry. Mono and bimetallic Ni-Fe nanoparticles with varied Ni-to-Fe ratios transform CO 2 and H 2 into intermediates and products of the acetyl-coenzyme A pathway-formate, acetate, and pyruvate-in mM range under mild hydrothermal conditions. Furthermore, Ni-Fe catalysts converted CO 2 to similar products without molecular H 2 by using water as a hydrogen source. Both CO 2 chemisorption analysis and post-reaction characterization of materials indicate that Ni and Fe metals play complementary roles for CO 2 fixation., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Halide perovskite materials, especially lead-based perovskites, have been widely used for optoelectronic and catalytic applications. However, the high toxicity of the lead element is a major concern that directs the research work toward lead-free halide perovskites, which could utilize bismuth as a promising candidate. Until now, the replacement of lead by bismuth in perovskites has been well studied by designing bismuth-based halide perovskite (BHP) nanomaterials with versatile physical-chemical properties, which are emerging in various application fields, especially heterogeneous photocatalysis. In this mini-review, we present a brief overview of recent progress in BHP nanomaterials for photocatalysis under visible light. The synthesis and physical-chemical properties of BHP nanomaterials have been comprehensively summarized, including zero-dimensional, two-dimensional nanostructures and hetero-architectures. Later, we introduce the photocatalytic applications of these novel BHP nanomaterials with visible-light response, improved charge separation/transport and unique catalytic sites. Due to advanced nano-morphologies, a well-designed electronic structure and an engineered surface chemical micro-environment, BHP nanomaterials demonstrate enhanced photocatalytic performance for hydrogen generation, CO 2 reduction, organic synthesis and pollutant removal. Finally, the challenges and future research directions of BHP nanomaterials for photocatalysis are discussed.

The chemical reactions that formed the building blocks of life at origins required catalysts, whereby the nature of those catalysts influenced the type of products that accumulated. Recent investigations have shown that at 100 °C awaruite, a Ni 3 Fe alloy that naturally occurs in serpentinizing systems, is an efficient catalyst for CO 2 conversion to formate, acetate, and pyruvate. These products are identical with the intermediates and products of the acetyl-CoA pathway, the most ancient CO 2 fixation pathway and the backbone of carbon metabolism in H 2 -dependent autotrophic microbes. Here, we show that Ni 3 Fe nanoparticles prepared via the hard-templating method catalyze the conversion of H 2 and CO 2 to formate, acetate and pyruvate at 25 °C under 25 bar. Furthermore, the 13 C-labeled pyruvate can be further converted to acetate, parapyruvate, and citramalate over Ni, Fe, and Ni 3 Fe nanoparticles at room temperature within one hour. These findings strongly suggest that awaruite can catalyze both the formation of citramalate, the C5 product of pyruvate condensation with acetyl-CoA in microbial carbon metabolism, from pyruvate and the formation of pyruvate from CO 2 at very moderate reaction conditions without organic catalysts. These results align well with theories for an autotrophic origin of microbial metabolism under hydrothermal vent conditions., (© 2023. The Author(s).)

Catalysis is involved in around 85 % of manufacturing industry and contributes an estimated 25 % to the global domestic product, with the majority of the processes relying on heterogeneous catalysis. Despite the importance in different global segments, the fundamental understanding of heterogeneously catalysed processes lags substantially behind that achieved in other fields. The newly established Max Planck-Cardiff Centre on the Fundamentals of Heterogeneous Catalysis (FUNCAT) targets innovative concepts that could contribute to the scientific developments needed in the research field to achieve net zero greenhouse gas emissions in the chemical industries. This Viewpoint Article presents some of our research activities and visions on the current and future challenges of heterogeneous catalysis regarding green industry and the circular economy by focusing explicitly on critical processes. Namely, hydrogen production, ammonia synthesis, and carbon dioxide reduction, along with new aspects of acetylene chemistry., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Serpentinizing hydrothermal systems generate H 2 as a reductant and harbor catalysts conducive to geochemical CO 2 conversion into reduced carbon compounds that form the core of microbial autotrophic metabolism. This study characterizes mineral catalysts at hydrothermal vents by investigating the interactions between catalytically active cobalt sites and silica-based support materials on H 2 -dependent CO 2 reduction. Heteroatom incorporated (Mg, Al, Ca, Ti, and Zr), ordered mesoporous silicas are applied as model support systems for the cobalt-based catalysts. It is demonstrated that all catalysts surveyed convert CO 2 to methane, methanol, carbon monoxide, and low-molecular-weight hydrocarbons at 180 °C and 20 bar, but with different activity and selectivity depending on the support modification. The additional analysis of the condensed product phase reveals the formation of oxygenates such as formate and acetate, which are key intermediates in the ancient acetyl-coenzyme A pathway of carbon metabolism. The Ti-incorporated catalyst yielded the highest concentrations of formate (3.6 mM) and acetate (1.2 mM) in the liquid phase. Chemisorption experiments including H 2 temperature-programmed reduction (TPR) and CO 2 temperature-programmed desorption (TPD) in agreement with density functional theory (DFT) calculations of the adsorption energy of CO 2 suggest metallic cobalt as the preferential adsorption site for CO 2 compared to hardly reducible cobalt-metal oxide interface species. The ratios of the respective cobalt species vary depending on the interaction strength with the support materials. The findings reveal robust and biologically relevant catalytic activities of silica-based transition metal minerals in H 2 -rich CO 2 fixation, in line with the idea that autotrophic metabolism emerged at hydrothermal vents.

Herein, we show that coupling boron with cobalt oxide tunes its structure and significantly boost its electrocatalytic performance for the oxygen evolution reaction (OER). Through a simple precipitation and thermal treatment process, a series of Co-B oxides with tunable morphologies and textural parameters were prepared. Detailed structural analysis supported first the formation of an disordered and partially amorphous material with nanosized Co 3 BO 5 and/or Co 2 B 2 O 6 being present on the local atomic scale. The boron modulation resulted in a superior OER reactivity by delivering a large current and an overpotential of 338 mV to reach a current density of 10 mA cm -2 in 1 M KOH electrolyte. Identical location transmission electron microscopy and in situ electrochemical Raman spectroscopy studies revealed alteration and surface re-construction of materials, and formation of CoO 2 and (oxy)hydroxide intermediate, which were found to be highly dependent on crystallinity of the samples., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Exploring single-atom catalysts (SACs) for the nitrate reduction reaction (NO 3 - ; NitRR) to value-added ammonia (NH 3 ) offers a sustainable alternative to both the Haber-Bosch process and NO 3 -adsorption, sluggish proton (H*) transfer kinetics, and preferred hydrogen evolution, their NO - -rich wastewater treatment. However, due to the insufficient electron deficiency and unfavorable electronic structure of SACs, resulting in poor NO 3 - -adsorption, sluggish proton (H*) transfer kinetics, and preferred hydrogen evolution, their NO 3 - -to-NH 3 selectivity and yield rate are far from satisfactory. Herein, a systematic theoretical prediction reveals that the local electron deficiency of an f -block Gd single atom (Gd SA ) can be significantly regulated upon coordination with oxygen-defect-rich NiO (Gd SA -D-NiO 400 orbital coupling and further improving the protonation kinetics of adsorption intermediates by rapid H* capture from water dissociation catalyzed by the adjacent oxygen vacancy site along with suppressed H* dimerization synergistically boosts the NH 3 - adsorption via strong Gd 5d -O 2p h)) along with superior structural stability, as revealed by 3 selectivity/yield rate. Motivated by DFT prediction, we delicately stabilized electron-deficient (strongly electrophilic) Gd SA on D-NiO 400 (∼84% strong electrophilic sites), which exhibited excellent alkaline NitRR activity (NH 3 Faradaic efficiency ∼97% and yield rate ∼628 μg/(mg cat h)) along with superior structural stability, as revealed by in situ Raman spectroscopy, significantly outperforming weakly electrophilic Gd nanoparticles, defect-free Gd SA -P-NiO 400 , and reported state-of-the-art catalysts.

Hydrogen gas, H 2 , is generated in serpentinizing hydrothermal systems, where it has supplied electrons and energy for microbial communities since there was liquid water on Earth. In modern metabolism, H 2 is converted by hydrogenases into organically bound hydrides (H - ), for example, the cofactor NADH. It transfers hydrides among molecules, serving as an activated and biologically harnessed form of H 2 . In serpentinizing systems, minerals can also bind hydrides and could, in principle, have acted as inorganic hydride donors-possibly as a geochemical protoenzyme, a 'geozyme'- at the origin of metabolism. To test this idea, we investigated the ability of H 2 to reduce NAD + in the presence of iron (Fe), cobalt (Co) and nickel (Ni), metals that occur in serpentinizing systems. In the presence of H 2 , all three metals specifically reduce NAD + to the biologically relevant form, 1,4-NADH, with up to 100% conversion rates within a few hours under alkaline aqueous conditions at 40 °C. Using Henry's law, the partial pressure of H 2 in our reactions corresponds to 3.6 mm, a concentration observed in many modern serpentinizing systems. While the reduction of NAD + by Ni is strictly H 2 -dependent, experiments in heavy water ( 2 H 2 O) indicate that native Fe can reduce NAD + both with and without H 2 . The results establish a mechanistic connection between abiotic and biotic hydride donors, indicating that geochemically catalysed, H 2 -dependent NAD + reduction could have preceded the hydrogenase-dependent reaction in evolution., (© 2022 The Authors. The FEBS Journal published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.)

Spectroscopic methods enabling real-time monitoring of dynamic surface processes are a prerequisite for identifying how a catalyst triggers a chemical reaction. We present an in situ photoluminescence spectroscopy approach for probing the thermocatalytic 2-propanol oxidation over mesostructured Co 3 O 4 nanowires. Under oxidative conditions, a distinct blue emission at ∼420 nm is detected that increases with temperature up to 280 °C, with an intermediate maximum at 150 °C. Catalytic data gained under comparable conditions show that this course of photoluminescence intensity precisely follows the conversion of 2-propanol and the production of acetone. The blue emission is assigned to the radiative recombination of unbound acetone molecules, the n ↔ π* transition of which is selectively excited by a wavelength of 270 nm. These findings open a pathway for studying thermocatalytic processes via in situ photoluminescence spectroscopy, thereby gaining information about the performance of the catalyst and the formation of intermediate products.

Ordered mesoporous CuNiCo oxides were prepared via nanocasting with varied Cu/Ni ratio to establish its impact on the electrochemical performance of the catalysts. Physicochemical properties were determined along with the electrocatalytic activities toward oxygen evolution/reduction reactions (OER/ORR). Combining Cu, Ni, and Co allowed creating active and stable bifunctional electrocatalysts. CuNiCo oxide (Cu/Ni≈1 : 4) exhibited the highest current density of 411 mA cm -2 at 1.7 V vs. reversible hydrogen electrode (RHE) and required the lowest overpotential of 312 mV to reach 10 mA cm -2 in 1 m KOH after 200 cyclic voltammograms. OER measurements were also conducted in the purified 1 m KOH, where CuNiCo oxide (Cu/Ni≈1 : 4) also outperformed NiCo oxide and showed excellent chemical and catalytic stability. For ORR, Cu/Ni incorporation provided higher current density, better kinetics, and facilitated the 4e - pathway of the oxygen reduction reaction. The tests in Li-O 2 cells highlighted that CuNiCo oxide can effectively promote ORR and OER at a lower overpotential., (© 2021 The Authors. ChemSusChem published by Wiley-VCH GmbH.)

The impact of reduction post-treatment and phase segregation of cobalt iron oxide nanowires on their electrochemical oxygen evolution reaction (OER) activity is investigated. A series of cobalt iron oxide spinel nanowires are prepared via the nanocasting route using ordered mesoporous silica as a hard template. The replicated oxides are selectively reduced through a mild reduction that results in phase transformation as well as the formation of grain boundaries. The detailed structural analyses, including the 57 Fe isotope-enriched Mössbauer study, validated the formation of iron oxide clusters supported by ordered mesoporous CoO nanowires after the reduction process. This affects the OER activity significantly, whereby the overpotential at 10 mA/cm 2 decreases from 378 to 339 mV and the current density at 1.7 V vs RHE increases by twofold from 150 to 315 mA/cm 2 . In situ Raman microscopy revealed that the surfaces of reduced CoO were oxidized to cobalt with a higher oxidation state upon solvation in the KOH electrolyte. The implementation of external potential bias led to the formation of an oxyhydroxide intermediate and a disordered-spinel phase. The interactions of iron clusters with cobalt oxide at the phase boundaries were found to be beneficial to enhance the charge transfer of the cobalt oxide and boost the overall OER activity by reaching a Faradaic efficiency of up to 96%. All in all, the post-reduction and phase segregation of cobalt iron oxide play an important role as a precatalyst for the OER., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

The synthesis of electrocatalyst and the electrode preparation were merged into a one-step process and proved to be a versatile method to synthesize metal oxide electrocatalysts on the conductive carbon paper (CP). Very simply, the metal precursor deposited on the CP was thermally treated by a torch-gun for just 6 s, resulting in the formation of RuO 2 , Co 3 O 4 , and mixed oxide nanoparticles. The material could be directly used as working electrode for oxygen evolution reaction (OER). Compared with commercial and other state-of-the-art electrocatalysts, the fabricated electrode showed a superior electrocatalytic activity for OER in 1 m HClO 4 and 1 m KOH in terms of not only a low overpotential to reach 10 mA cm -2 but also a high current density at 1.6 V RHE with satisfying a long-term stability. The novel strategy without requiring time-consuming and uneconomical steps could be expanded to the preparation of various metal oxides on conductive substrates towards diverse electrocatalytic applications., (© 2021 The Authors. ChemSusChem published by Wiley-VCH GmbH.)

Water electrolysis that results in green hydrogen is the key process towards a circular economy. The supply of sustainable electricity and availability of oxygen evolution reaction (OER) electrocatalysts are the main bottlenecks of the process for large-scale production of green hydrogen. A broad range of OER electrocatalysts have been explored to decrease the overpotential and boost the kinetics of this sluggish half-reaction. Co-, Ni-, and Fe-based catalysts have been considered to be potential candidates to replace noble metals due to their tunable 3d electron configuration and spin state, versatility in terms of crystal and electronic structures, as well as abundance in nature. This Review provides some basic principles of water electrolysis, key aspects of OER, and significant criteria for the development of the catalysts. It provides also some insights on recent advances of Co-, Ni-, and Fe-based oxides and a brief perspective on green hydrogen production and the challenges of water electrolysis., (© 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Herein, we report nanosecond, single-pulse laser post-processing (PLPP) in a liquid flat jet with precise control of the applied laser intensity to tune structure, defect sites, and the oxygen evolution reaction (OER) activity of mesostructured Co 3 O 4 . High-resolution X-ray diffraction (XRD), Raman, and X-ray photoelectron spectroscopy (XPS) are consistent with the formation of cobalt vacancies at tetrahedral sites and an increase in the lattice parameter of Co 3 O 4 after the laser treatment. X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES) further reveal increased disorder in the structure and a slight decrease in the average oxidation state of the cobalt oxide. Molecular dynamics simulation confirms the surface restructuring upon laser post-treatment on Co 3 O 4 . Importantly, the defect-induced PLPP was shown to lower the charge transfer resistance and boost the oxygen evolution activity of Co 3 O 4 . For the optimized sample, a 2-fold increment of current density at 1.7 V vs RHE is obtained and the overpotential at 10 mA/cm 2 decreases remarkably from 405 to 357 mV compared to pristine Co 3 O 4 . Post-mortem characterization reveals that the material retains its activity, morphology, and phase structure after a prolonged stability test.

In view of rising ecological awareness, materials development is primarily aimed at improving the performance and efficiency of innovative and more elaborate materials. However, a materials performance figure of merit should include essential aspects of materials: environmental impact, economic constraints, technical feasibility, etc. Thus, we promote the inclusion of sustainability criteria already during the materials design process. With such a holistic design approach, new products may be more likely to meet the circular economy requirements than when traditional development strategies are pursued. Using catalysts for water electrolysis as an example, we present a modelling method based on experimental data to holistically evaluate processes., (© 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Amorphous Ti x O y with high surface area has attracted significant interest as photocatalyst with higher activity in ultraviolet (UV) light-induced water splitting applications compared to commercial nanocrystalline TiO 2 . Under photocatalytic operation conditions, the structure of the molecular titanium alkoxide precursor rearranges upon hydrolysis and leads to higher connectivity of the structure-building units. Structurally ordered domains with sizes smaller than 7 Å form larger aggregates. The experimental scattering data can be explained best with a structure model consisting of an anatase-like core and a distorted shell. Upon exposure to UV light, the white Ti x O y suspension turns dark corresponding to the reduction of Ti 4+ to Ti 3+ as confirmed by electron energy loss spectroscopy (EELS). Heat-induced crystallisation was followed by in situ temperature-dependent total scattering experiments. First, ordering in the Ti-O environment takes place upon to 350 °C. Above this temperature, the distorted anatase core starts to grow but the structure obtained at 400 °C is still not fully ordered., (© 2021 The Authors. Published by Wiley-VCH GmbH.)

The composite of the metal-organic framework (MOF) Ni(Fe)-MOF-74 and the highly conductive carbon material ketjenblack (KB) could be easily obtained from the in-situ MOF synthesis in a one-step solvothermal reaction. The composite material features a remarkable electrochemical oxygen evolution reaction (OER) performance where the overpotential at 10 mA/cm 2 and the current density at 1.7 V RHE are recorded as 0.274 V RHE and 650 mA/cm 2 , respectively, in 1 mol/L KOH. In particular, the activation of nickel-iron clusters from the MOF under an applied anodic bias steadily boosts the OER performance. Although Ni(Fe)-MOF-74 goes through some structural modification during the electrochemical measurements, the stabilized and optimized composite material shows excellent OER performance. This simple strategy to design highly-efficient electrocatalysts, utilizing readily available precursors and carbon materials, will leverage the use of diverse metal-organic complexes into electrode fabrication with a high energy conversion efficiency., (© 2021 The Authors. ChemPlusChem published by Wiley-VCH GmbH.)

Achieving long-term device stability is one of the most challenging issues that impede the commercialization of perovskite solar cells (PSCs). Recent studies have emphasized the significant role of the cathode interfacial layer (CIL) in determining the stability of inverted p-i-n PSCs. However, experimental investigations focusing on the influence of the CIL on PSC degradation have not been systematically carried out to date. In this study, a comparative analysis was performed on the PSC device stability by using four different CILs including practical oxides like ZnO and TiO x . A new implemented co-doping approach was found to results in high device performance and enhanced device stability. The PSC with a thick film configuration of chemically modified TiO x CIL preserves over 77 % of its initial efficiencies of 17.24 % for 300 h under operational conditions without any encapsulation. The PSCs developed are among the most stable reported for methylammonium lead iodide (MAPbI 3 ) perovskite compositions., (© 2021 The Authors. ChemSusChem published by Wiley-VCH GmbH.)

Heusler compounds have potential in electrocatalysis because of their mechanical robustness, metallic conductivity, and wide tunability in the electronic structure and element compositions. This study reports the first application of Co 2 YZ-type Heusler compounds as electrocatalysts for the oxygen evolution reaction (OER). A range of Co 2 YZ crystals was synthesized through the arc-melting method and the e g orbital filling of Co was precisely regulated by varying Y and Z sites of the compound. A correlation between the e g orbital filling of reactive Co sites and OER activity was found for Co 2 MnZ compounds (Z=Ti, Al, V, and Ga), whereby higher catalytic current was achieved for e g orbital filling approaching unity. A similar trend of e g orbital filling on the reactivity of cobalt sites was also observed for other Heusler compounds (Co 2 VZ, Z=Sn and Ga). This work demonstrates proof of concept in the application of Heusler compounds as a new class of OER electrocatalysts, and the influence of the manipulation of the spin orbitals on their catalytic performance., (© 2020 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

The exact formation mechanism of tantalum oxides (and in general, metal/mixed metal oxides) from alkoxide precursors is still not fully understood, particularly when forming cluster-like or amorphous materials. The structural evolution of Ta-based oxides was studied in detail using X-ray total scattering experiments along with subsequent pair distribution function (PDF) analyses. Starting from a tantalum alkoxide precursor (Ta 2 (OEt) 10 ), the formation of hydrolysed Ta x O y H z clusters in highly diluted aqueous solution was analysed. From the PDF data, the connectivity and arrangement of Ta x O y octahedra in the cluster could be deduced as well as the approximate size of the clusters (<1 nm). Construction of cluster models allowed for identification of common structural motifs in the Ta x O y H z clusters, ruling out the formation of chain- or ring-like clusters. More likely, bulky clusters with a high number of corner-sharing octahedra are formed. After separation of the amorphous solid from the liquid, temperature-induced crystallisation processes were monitored via in situ total scattering experiments. Between room temperature and 600 °C, only small rearrangements of the amorphous structure are observed. At about 610 °C, amorphous Ta x O y H z transforms directly into crystalline orthorhombic L-Ta 2 O 5 without formation of any crystalline intermediate structures.

Herein, we show that the performance of mesostructured cobalt oxide electrocatalyst for oxygen evolution reaction (OER) can be significantly enhanced by coupling of silver species. Various analysis techniques including pair distribution function and Rietveld refinement, X-ray absorption spectroscopy at synchrotron as well as advanced electron microscopy revealed that silver exists as metallic Ag particles and well-dispersed Ag 2 O nanoclusters within the mesostructure. The benefits of this synergy are twofold for OER: highly conductive metallic Ag improves the charge transfer ability of the electrocatalysts while ultra-small Ag 2 O clusters provide the centers that can uptake Fe impurities from KOH electrolyte and boost the catalytic efficiency of Co-Ag oxides. The current density of mesostructured Co 3 O 4 at 1.7 V RHE is increased from 102 to 211 mA cm -2 with incorporation of silver spices. This work presents the dual role of silver moieties and demonstrates a simple method to increase the OER activity of Co 3 O 4 ., (© 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

Hydrogen gas, H 2 , is generated by alkaline hydrothermal vents through an ancient geochemical process called serpentinization, in which water reacts with iron-containing minerals deep within the Earth's crust. H 2 is the electron donor for the most ancient and the only energy-releasing route of biological CO 2 fixation, the acetyl-CoA pathway. At the origin of metabolism, CO 2 fixation by hydrothermal H 2 within serpentinizing systems could have preceded and patterned biotic pathways. Here we show that three hydrothermal minerals-greigite (Fe 3 S 4 ), magnetite (Fe 3 O 4 ) and awaruite (Ni 3 Fe)-catalyse the fixation of CO 2 with H 2 at 100 °C under alkaline aqueous conditions. The product spectrum includes formate (up to 200 mM), acetate (up to 100 µM), pyruvate (up to 10 µM), methanol (up to 100 µM) and methane. The results shed light on both the geochemical origin of microbial metabolism and the nature of abiotic formate and methane synthesis in modern hydrothermal vents.

Direct selective oxidation of hydrocarbons to oxygenates by O 2 is challenging. Catalysts are limited by the low activity and narrow application scope, and the main focus is on active C-H bonds at benzylic positions. In this work, stable, lead-free, Cs 3 Bi 2 Br 9 halide perovskites are integrated within the pore channels of mesoporous SBA-15 silica and demonstrate their photocatalytic potentials for C-H bond activation. The composite photocatalysts can effectively oxidize hydrocarbons (C 5 to C 16 including aromatic and aliphatic alkanes) with a conversion rate up to 32900 μmol g cat  h -1  h -1 )-H bond activation by photoinduced charges.3 )-H bond activation by photoinduced charges., (© 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

Sub-5 nm cobalt oxide nanoparticles are produced in a flowing water system by pulsed laser fragmentation in liquid (PLFL). Particle fragmentation from 8 nm to 4 nm occurs and is attributed to the oxidation process in water where oxidative species are present and the local temperature is rapidly elevated under laser irradiation. Significantly higher surface area, crystal phase transformation, and formation of structural defects (Co 2+ defects and oxygen vacancies) through the PLFL process are evidenced by detailed structural characterizations by nitrogen physisorption, electron microscopy, synchrotron X-ray diffraction, and X-ray photoelectron spectroscopy. When employed as electrocatalysts for the oxygen evolution reaction under alkaline conditions, the fragmented cobalt oxides exhibit superior catalytic activity over pristine and nanocast cobalt oxides, delivering a current density of 10 mA cm -2 at 369 mV and a Tafel slope of 46 mV dec -1 , which is attributed to a larger exposed active surface area, the formation of defects, and an increased charge transfer rate. The study provides an effective approach to engineering cobalt oxide nanostructures in a flowing water system, which shows great potential for sustainable production of active cobalt catalysts., (© 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

The band inversion in topological phase matters bring exotic physical properties such as the topologically protected surface states (TSS). They strongly influence the surface electronic structures of the materials and could serve as a good platform to gain insight into the surface reactions. Here we synthesized high-quality bulk single crystals of Co 3 Sn 2 S 2 that naturally hosts the band structure of a topological semimetal. This guarantees the existence of robust TSS from the Co atoms. Co 3 Sn 2 S 2 crystals expose their Kagome lattice that constructed by Co atoms and have high electrical conductivity. They serves as catalytic centers for oxygen evolution process (OER), making bonding and electron transfer more efficient due to the partially filled orbital. The bulk single crystal exhibits outstanding OER catalytic performance, although the surface area is much smaller than that of Co-based nanostructured catalysts. Our findings emphasize the importance of tailoring TSS for the rational design of high-activity electrocatalysts.

Herein, an innovative approach was developed by using stable, lead-free halide perovskite for solar-driven organic synthesis. The ring-opening reaction of epoxides was chosen as a model system for the synthesis of value-added β-alkoxy alcohols, which require energy-intensive process conditions and corrosive, strong acids for conventional synthesis. The developed concept included the in situ preparation of Cs 3 Bi 2 Br 9 and its simultaneous application as photocatalyst for epoxide alcoholysis under visible-light irradiation in air at 293 K, with exceptional high activity and selectivity ≥86 % for β-alkoxy alcohols and thia-compounds. The Cs 3 Bi 2 Br 9 photocatalyst exhibited good stability and recyclability. In contrast, the lead-based perovskite showed a conversion rate of only 1 %. The origin of the unexpected catalytic behavior was attributed to the combination of the photocatalytic process and the presence of suitable Lewis-acidic centers on the surface of the bismuth halide perovskite photocatalyst., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In situ formation of electroactive cobalt species for the oxygen evolution reaction is simply achieved by applying an anodic bias to a commercially available cobalt precursor and Nafion binder mixture coated on a glassy carbon electrode. This preparation does not require energy-intensive materials preparation steps or noble metals, yet a low overpotential of 322 mV at 10.2 mA cm -2 and a high current density of more than 300 mA cm -2 at 1.7 V NHE were obtained in 1 m KOH. An operando electrochemical Raman spectroscopy study confirmed the formation of cobalt oxyhydroxide species and the iron stimulated the equilibrium state between Co 3+ and Co 4+ . The iron present in the alkali electrolyte or ink solution effectively activated the cobalt species, and most of the first row transition metals could also enhance the catalytic performance. The concept presented here is one of the simplest strategies for preparing highly active electrocatalysts and is very flexible for the replacement of cobalt by other transition metals., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Rock⁻water⁻carbon interactions germane to serpentinization in hydrothermal vents have occurred for over 4 billion years, ever since there was liquid water on Earth. Serpentinization converts iron(II) containing minerals and water to magnetite (Fe₃O₄) plus H₂. The hydrogen can generate native metals such as awaruite (Ni₃Fe), a common serpentinization product. Awaruite catalyzes the synthesis of methane from H₂ and CO₂ under hydrothermal conditions. Native iron and nickel catalyze the synthesis of formate, methanol, acetate, and pyruvate-intermediates of the acetyl-CoA pathway, the most ancient pathway of CO₂ fixation. Carbon monoxide dehydrogenase (CODH) is central to the pathway and employs Ni⁰ in its catalytic mechanism. CODH has been conserved during 4 billion years of evolution as a relic of the natural CO₂-reducing catalyst at the onset of biochemistry. The carbide-containing active site of nitrogenase-the only enzyme on Earth that reduces N₂-is probably also a relic, a biological reconstruction of the naturally occurring inorganic catalyst that generated primordial organic nitrogen. Serpentinization generates Fe₃O₄ and H₂, the catalyst and reductant for industrial CO₂ hydrogenation and for N₂ reduction via the Haber⁻Bosch process. In both industrial processes, an Fe₃O₄ catalyst is matured via H₂-dependent reduction to generate Fe₅C₂ and Fe₂N respectively. Whether serpentinization entails similar catalyst maturation is not known. We suggest that at the onset of life, essential reactions leading to reduced carbon and reduced nitrogen occurred with catalysts that were synthesized during the serpentinization process, connecting the chemistry of life and Earth to industrial chemistry in unexpected ways.

Halide perovskites have prompted the evolution of the photovoltaic field and simultaneously demonstrated their great potential for application in other optoelectronic devices. A fundamental understanding of their structure-property relationship is essential to fabricate novel materials and high-performance devices. This review gives a perspective on different synthetic methodologies for the preparation of halide perovskites and highlights the effects of structural factors such as crystal structure, grain size, nanoscale dimensionality, patterned arrangement, and hierarchical structure on their optoelectronic properties. The main emphasis is given to 0D, 1D and 2D nanostructured materials including their common synthesis methods and key structural properties. Structural factors should be precisely controlled during the material preparation and device fabrication to improve the performance of targeted applications.