Biocatalysis, which involves using enzymes to address synthetic challenges of significance to humans, has rapidly developed into a pivotal technology for chemical innovation. Over the past decade, there has been a notable increase in the use of metalloproteins as catalysts for abiotic, synthetically valuable carbene and nitrene transfer reactions. This trend highlights the adaptability of protein-based catalysts and our growing ability to harness this potential for novel enzyme chemistry. This review focuses on the most recent advancements in metalloenzyme-catalyzed carbene and nitrene transfer reactions, including cyclopropanation, carbene Y-H and C-H insertions, Doyle-Kirmse reactions, aldehyde olefinations, nitrene azide-to-aldehyde conversions, and nitrene C-H insertion. A variety of protein scaffolds have been engineered to offer varied levels of reactivity and selectivity towards pharmaceutically relevant compounds. The application of these new catalysts in preparative-scale synthesis underscores their emerging biotechnological significance. Furthermore, insights into key intermediate and determining factors in stereochemistry are offering valuable guidance for engineering metalloproteins, thereby expanding the scope and utility of these non-natural activities.

Hydrogen peroxide (H₂O₂), as an essential and green chemical, is extensively used in energy and environmental applications. However, the production of H₂O₂ primarily relies on the anthraquinone method, which is an energy-intensive method involving multi-step reactions, producing harmful by-product wastes. Solar-driven H₂O₂ production, an alternative route for H₂O₂ generation, is a green and sustainable technology since it only utilizes water and oxygen as feedstock. However, the rapid recombination of charge carriers as well as insufficient redox capability limit the photocatalytic H₂O₂ production performance. Constructing step-scheme (S-scheme) heterojunction photocatalysts has been regarded as an effective strategy to address these drawbacks because it not only achieves spatially separated charge carriers, but also preserves redox capability of the photocatalytic system. This paper covers the recent advances of S-scheme heterojunction photocatalysts for H₂O₂ production in terms of basic principles, characterization techniques, and preparation strategies. Moreover, the mechanism and advantages of S-scheme heterojunction for photocatalytic H₂O₂ generation are systematically discussed. The recent S-scheme heterojunction designs, including inorganic-organic heterojunction, inorganic-inorganic heterojunction, and organic-organic heterojunction, are summarized. Lastly, the challenges and research directions of S-scheme photocatalysts for H₂O₂ generation are presented.

The study of the oxygen evolution reaction (OER) mechanism is vital for advancing our understanding of this pivotal energy conversion process. This review synthesizes recent advancements in OER mechanism, emphasizing the intricate relationship between catalytic mechanisms and catalyst design. This review discusses the connotation and cutting-edge progress of traditional mechanisms such as adsorbate evolution mechanism (AEM) and lattice oxygen mechanism (LOM) as well as emerging pathways including oxide path mechanism (OPM), oxo-oxo coupling mechanism (OCM), and intramolecular oxygen coupling mechanism (IMOC) etc. Innovative research progress on the coexistence and transformation of multiple mechanisms is highlighted, and the intrinsic factors that influence these dynamic processes are summarized. Advanced characterization techniques and theoretical modeling are underscored as indispensable tools for revealing these complex interactions. This review provides guiding principles for mechanism-based catalyst design. Finally, in view of the multidimensional challenges currently faced by OER mechanisms, prospects for future research are given to bridge the gap between mechanism innovation and experimental verification and application. This comprehensive review provides valuable perspectives for advancing clean energy technologies and achieving sustainable development.

Directed degradation of abundant renewable lignin into small aromatic compounds is crucial for lignin valorization but challenging. The degradation of lignin in natural environments typically involves multienzyme synergy. However, the proteinaceous characteristics of lignin-degrading enzymes restrict their accessibility to certain regions of intricate lignin, resulting in the multienzyme systems being unable to fully demonstrate their effectiveness. Herein, a de novo biomimetic enzyme-nanozyme hybrid system was constructed by combining λ-MnO₂ nanozyme with laccase CotA from Bacillus subtilis, aimed at facilitating lignin degradation under mild conditions. The lignin degradation rate of the CotA + λ-MnO₂ hybrid system was determined to be 25.15%, which was much higher than those of the lignin degradation systems with only laccase CotA (15.32%) or λ-MnO₂ nanozyme (14.90%). Notably, the proportion of aromatic chemicals in the products derived from the hybrid system reached as much as 48%, which was 41.2% and 118.2% higher than those of the CotA- and λ-MnO₂-catalyzed systems, respectively. Analysis of products mapping and lignin structure changes suggested that the higher proportion of aromatic compounds in the CotA + λ-MnO₂ hybrid system was more likely to benefit from the laccase-mediated methoxylation. Moreover, electron paramagnetic resonance analysis indicated that the intensity and kind of free radicals such as •OH and •O₂^- are closely linked to the degradation rate and reaction type. This work is the inaugural application of an enzyme-nanozyme hybrid system for lignin degradation, demonstrating the potential of the synergistic interaction between enzyme and nanozyme in the directed degradation of lignin.

Multienzyme cascades enable the sequential synthesis of complex chemicals by combining multiple catalytic processes in one pot, offering considerable time and cost savings compared to a series of separate batch reactions. However, challenges related to coordination and regulatory interplay among multiple enzymes reduce the catalytic efficiency of such cascades. Herein, we genetically programmed a scaffold framework that selectively and orthogonally recruits enzymes as designed. The system was then used to generate multienzyme complexes of D-allulose 3-epimerase (DAE), ribitol dehydrogenase (RDH), and formate dehydrogenase (FDH) for rare sugar production. This scaffolded multienzymatic assembly achieves a 10.4-fold enhancement in the catalytic performance compared to its unassembled counterparts, obtaining allitol yield of more than 95%. Molecular dynamics simulations revealed that shorter distances between neighboring enzymes in scaffold-mounted complexes facilitated the transfer of reaction intermediates. A dual-module catalytic system incorporating (1) scaffold-bound complexes of DAE, RDH, and FDH and (2) scaffold-bound complexes of alcohol dehydrogenase and NADH oxidase expressed intracellularly in E. coli was used to synthesize D-allulose from D-fructose. This system synthesized 90.6% D-allulose from 300 g L⁻¹ D-fructose, with a space-time yield of 13.6 g L⁻¹ h⁻¹. Our work demonstrates the programmability and versatility of scaffold-based strategies for the advancement of multienzyme cascades.

Solar-driven Fenton-like reactions are promising strategies for degrading pharmaceutical wastewater to address environmental challenges and antibiotic pollution. However, its efficacy is limited by suboptimal light absorption efficiency, rapid charge recombination, and inadequate interfacial charge transfer. In this study, an inorganic/organic S-scheme photo-Fenton system of pseudobrookite/carbon nitride (FTOCN) was synthesized via a hydrothermally coupled calcination process for the effective purification of tetracycline antibiotics under visible-light irradiation. The optimized FTOCN-2 heterostructure exhibits a significantly enhanced TC degradation capacity of 90% within 60 min. The rate constant of FTOCN-2 is 1.6 and 5.2 times greater than those of FTO and CN, respectively. Furthermore, FTOCN exhibits high antibacterial efficacy, highlighting its potential application in the purification of natural water. Measurements via a range of analytical techniques, including Kelvin probe force microscopy, density functional theory calculations, in situ X-ray photoelectron spectroscopy, and femtosecond transient absorption spectroscopy, corroborate the S-scheme mechanism. This study provides a novel perspective for the development of photo-Fenton systems with S-scheme heterojunctions for water purification.

The establishment of S-scheme heterojunctions has arisen as a promising strategy for the advancement of efficient photocatalytic systems with superior charge separation and redox ability, specifically for H₂O₂ production. In this investigation, an innovative 2D/2D g-C₃N₄/BiOBr S-scheme heterojunction was meticulously engineered through an in situ growth methodology. The synthetic composites exhibit boosted H₂O₂ production activity, achieving a peak generation rate of 392 μmol L^-1 h^-1, approximately 8.7-fold and 2.1-fold increase over the pristine BiOBr and g-C₃N₄, respectively. Such a superior activity should be attributed to the highly efficient charge separation and migration mechanisms, along with the sustained robust redox capability of S-scheme heterostructure, which are verified by time-resolved photoluminescence spectroscopy, photocurrent test and electron paramagnetic resonance measurements. Furthermore, the interfacial electric field induced S-scheme charge transfer mechanism between g-C₃N₄ and BiOBr is systematically certificated by in situ irradiated X-ray photoelectron spectroscopy and density functional theory calculation. This research offers a comprehensive protocol for the systematic development and construction of highly efficient S-scheme heterojunction photocatalysts, specifically tailored for enhanced H₂O₂ production.

Devising S-scheme heterostructure is considered as a cutting-edge strategy for advanced photocatalysts with effectively segregated photo-carriers and prominent redox potential for emerging organic pollutants control. Herein, an S-scheme Ag₂CO₃/C₃N₅ heterojunction photocatalyst was developed via a simple in situ chemical deposition procedure, and further photoreduction operation made metallic Ag (size: 3.5-12.5 nm) being in situ formed on Ag₂CO₃/C₃N₅ for a plasmonic S-scheme Ag/Ag₂CO₃/C₃N₅ heterojunction photocatalyst. Consequently, Ag/Ag₂CO₃/C₃N₅ manifests pronouncedly upgraded photocatalytic performance toward oxytetracycline degradation with a superior photoreaction rate constant of 0.0475 min^‒1, which is 13.2, 3.9 and 2.2 folds that of C₃N₅, Ag₂CO₃, and Ag₂CO₃/C₃N₅, respectively. As evidenced by comprehensive characterizations and density functional theory calculations, the localized surface plasmon resonance effect of metallic Ag and the unique S-scheme charge transfer mechanism in 0D/0D/2D Ag/Ag₂CO₃/C₃N₅ collaboratively strengthen the visible-light absorption, and facilitate the effective separation of powerful charge carriers, thereby significantly promoting the generation of reactive species like ·OH^-, h⁺ and ·O₂^- for efficient oxytetracycline destruction. Moreover, four consecutive cycles demonstrate the reusability of Ag/Ag₂CO₃/C₃N₅. Furthermore, the authentic water purification tests affirm its practical application potential. This work not only provides a candidate strategy for advancing S-scheme heterojunction photocatalysts but also makes a certain contribution to water decontamination.

Photocatalytic ozonation holds promise for advanced water purification, yet its development has been hindered by a limited understanding of ozone activation mechanisms and its related photogenerated electron transfer dynamics. Herein, we employed in-situ DRIFTS and Raman spectroscopy to elucidate the distinct adsorption and activation behaviors of ozone (O₃) on the {001} and {110} crystal facets of Bi₂O₂CO₃ (BOC) nanosheets. BOC-{001} demonstrates superior photocatalytic ozonation performance, with 85% phenol mineralization and excellent durability, significantly outperforming the 53% mineralization rate of BOC-{110}. This enhanced activity is attributed to non-dissociative ozone adsorption and favorable adsorption energy over {001} facet, which facilitate the one-electron O₃ reduction pathway. Furthermore, crystal facet engineering strengthens the built-in electric field, promoting exciton dissociation and the generation of localized charge carriers. The synergistic effects of optimized electron availability and ozone adsorption significantly boost the production of reactive oxygen species. These findings provide a deeper understanding of the critical roles of O₃ adsorption and electron transfer in radical generation, which could provide some guidance for the strategic development of highly effective photocatalytic ozonation catalysts.

Photoelectrocatalytic (PEC) seawater splitting as a green and sustainable route to harvest hydrogen is attractive yet hampered by low activity of photoanodes and unexpected high selectivity to the corrosive and toxic chlorine. Especially, it is full of challenges to unveil the key factors influencing the selectivity of such complex PEC processes. Herein, by regulating the energy band and surface structure of the anatase TiO₂ nanotube array photoanode via nitrogen-doping, the seawater PEC oxidation shifts from Cl^- oxidation reaction (ClOR) dominant on the TiO₂ photoanode (61.6%) to oxygen evolution reaction (OER) dominant on the N-TiO₂ photoanode (62.9%). Comprehensive investigations including operando photoelectrochemical FTIR and DFT calculations unveil that the asymmetric hydrogen-bonding water at the N-TiO₂ electrode/electrolyte interface enriches under illumination, facilitating proton transfer and moderate adsorption strength of oxygen-intermediates, which lowers the energy barrier for the OER yet elevates the energy barrier for the ClOR, resulting to a promoted selectivity towards the OER. The work sheds light on the underlying mechanism of the PEC water oxidation processes, and highlights the crucial role of interfacial water on the PEC selectivity, which could be regulated by controlling the energy band and the surface structure of semiconductors.

The oxygen evolution reaction (OER) serves as a fundamental half-reaction in the electrolysis of water for hydrogen production, which is restricted by the sluggish OER reaction kinetics and unable to be practically applied. The traditional lattice oxygen oxidation mechanism (LOM) offers an advantageous route by circumventing the formation of M-OOH* in the adsorption evolution mechanism (AEM), thus enhancing the reaction kinetics of the OER but resulting in possible structural destabilization due to the decreased M-O bond order. Fortunately, the asymmetry of tetrahedral and octahedral sites in transition metal spinel oxides permits the existence of non-bonding oxygen, which could be activated by rational band structure design for direct O-O coupling, where the M-O bond maintains its initial bond order. Here, non-bonding oxygen was introduced into NiFe₂O₄ via annealing in an oxygen-deficient atmosphere. Then, in-situ grown sulfate species on octahedral nickel sites significantly improved the reactivity of the non-bonding oxygen electrons, thereby facilitating the transformation of the redox center from metal to oxygen. LOM based on non-bonding oxygen (LOM_NB) was successfully activated within NiFe₂O₄, exhibiting a low overpotential of 206 mV to achieve a current density of 10 mA cm^-2 and excellent durability of stable operation for over 150 h. Additionally, catalysts featuring varying band structures were synthesized for comparative analysis, and it was found that the reversible redox processes of non-bonding oxygen and the accumulation of non-bonding oxygen species containing 2p holes are critical prerequisites for triggering and sustaining the LOM_NB pathway in transition metal spinel oxides. These findings may provide valuable insights for the future development of spinel-oxide-based LOM catalysts.

The slow-proton-fast-electron process severely limits the catalytic efficiency of oxygen evolution reaction. A method is proposed to accelerate proton transfer by building up local electric fields. Modifying acetic, ethanedioic and propanetricarboxylic (C₆H₈O₆) ligands on BiVO₄ surface results in a potential difference between BiVO₄ and ligands that generates a local electric field which serves as a driving force for proton transfer. Among the ligands, carrying the strongest electron-withdrawing ability, the modification of C₆H₈O₆ forms the strongest local electric field and leads to the fastest proton transfer and the smallest thermodynamic overpotential. C₆H₈O₆-BiVO₄ exhibits 3.5 times photocurrent density as high as that of pure BiVO₄, which is 3.50 mA cm^-2 at 1.23 V_RHE. The onset potential of C₆H₈O₆-BiVO₄ shifts negatively from 0.70 to 0.38 V_RHE. The mechanism for OER transitions from thermodynamically high energy proton-coupled electron transfer to thermodynamically low energy electron transfer as proton transfer is accelerated.

Catalytic oxidation plays a crucial role in chemical industry, in which the utilization of abundant and environmental-friendly oxygen (O₂) as oxidant aligns with sustainable development principles in green chemistry. However, the intrinsic inertness of ground-state O₂ molecule poses a long-standing challenge in developing an efficient non-noble metal-based catalyst. Herein, inspired by the electron transfer process in respiratory chain, we engineered long-range N_V to mediate Fe₁ center for O₂ activation in aerobic oxidation. Combined in/quasi-situ spectroscopic characterizations and control experiments suggest the Fe₁ site efficiently adsorbs O₂, and the N_V site facilitates electron delocalization to adjacent Fe₁, providing efficient transformation of O₂ to reactive oxygen species that boost oxidation reactions mildly. This Fe₁--N_V single-atom catalyst demonstrates outstanding catalytic performance in aerobic oxidations of alkanes, N-heterocycles, alcohols, and amines under relatively mild conditions. Our findings offer a new perspective for designing high-efficiency heterogeneous catalysts in aerobic oxidations, promising various potential applications.

To convert carbon dioxide into high-value-added liquid products such as formate with renewable electricity (CO₂RR) is a promising strategy of CO₂ resource utilization. The key is to find a highly efficient and selective electrocatalyst for CO₂RR. Herein, clustered Bi₂₈O₃₂(SO₄)₁₀ was found to show a high formate Faradaic efficiency (FE_formate) of 96.2% at -1.1 V_RHE and FE_formate above 90% in a wide potential range from -0.9 to -1.3 V_RHE in H-type cell, surpassing the corresponding layered Bi₂O₂SO₄ (85.6% FE_formate at -1.1 V_RHE). The advantageous CO₂RR performance of Bi₂₈O₃₂(SO₄)₁₀ over Bi₂O₂SO₄ was ascribed to a special two-step in-situ reconstruction process, consisting of Bi₂₈O₃₂(SO₄)₁₀ → Bi_-2.1/Bi₂O₂CO₃ → Bi_-2.1/Bi_-0.6 during CO₂RR. It gave metallic Bi_-2.1 with lattice distortion of -2.1% at the first step and metallic Bi_-0.6 with lattice distortion of -0.6% at the second step. In contrast, the usual layered Bi₂O₂SO₄ only formed metallic Bi_-0.6 with weaker lattice strain. The metallic Bi_-2.1 revealed higher efficiency in stabilizing *CO₂ intermediate and reducing the energy barrier of CO₂RR, while suppressing hydrogen evolution reaction and CO formation. This work delivers a high-performance cluster-type Bi₂₈O₃₂(SO₄)₁₀ electrocatalyst for CO₂RR, and elucidates the origin of superior performance of clustered Bi₂₈O₃₂(SO₄)₁₀ electrocatalysts compared with layered Bi₂O₂SO₄.

Metal-support interaction (MSI) is regarded as an indispensable manner to stabilize active metals and modulate catalytic activity, which shows great potentials in developing of efficient hydrogen evolution reaction (HER) electrode with high activity and strong robustness. Herein, this work presents a novel heterostructure with ultrafine platinum quantum dots (Pt QDs) on defective catalytic supports derived from metal-organic frameworks (MOFs). It is indicated substantial oxygen vacancies can be generated and Pt-Pt bonds can be optimized through topological transformation. The resulting Pt/T-NiFe-BDC (BDC: C₈H₆O₄) exhibits competitive HER activity in alkaline seawater, attaining ultralow overpotentials of 158 and 266 mV at 500 and 1000 mA cm^-2 with fast kinetics and outstanding stability. An asymmetric water electrolyzer using Pt/T-NiFe-BDC as a cathode only requires a voltage of 1.89 V to generate an industrial density of 1000 mA cm^-2 and shows no attenuation in 500-h continuous test at 500 mA cm^-2. Theoretical calculations and in-situ spectroscopic analysis reveal the reversible hydrogen spillover mechanism, in which oxygen vacancies facilitate the sluggish water dissociation and Pt QDs promote the H* combination. This study provides a new paradigm to engineer metal-supported catalysts for efficient and robust seawater splitting.

Single-atom Fe catalysts show significant promise in the electrocatalytic reduction of CO₂ (CO₂RR), while their performance remains inferior to that of precious metal catalysts due to the overly strong binding of *CO intermediates. Although the introduction of heteroatoms or transition metal sites can modulate the binding strength of *CO on Fe sites, these regulators often induce competitive hydrogen evolution reaction (HER) with reduced Faraday efficiency (FE). In this work, we employ HER-inert Sn as a regulator to tune the electronic structure of Fe, weakening *CO adsorption and enhancing CO₂RR performance. Diatomic Fe-Sn pairs supported on N-doped carbon (Fe-Sn/NC) were synthesized, achieving FE for CO exceeding 90% over a broad potential range from −0.4 to −0.9 V versus the reversible hydrogen electrode. Fe-Sn/NC shows a high turnover frequency of 1.5 × 10⁴ h⁻¹, much higher than that of Fe/NC. Characterization results and theoretical calculations demonstrate that bonding Sn site to Fe generates electron-rich Fe centers, effectively reducing the adsorption strength of *CO without triggering HER. Additionally, Fe-Sn/NC exhibits exceptional activity in hydrazine oxidation performance (HzOR). The HzOR-assisted CO₂RR system using Fe-Sn/NC as electrodes reduces energy consumption by 38% compared with the conventional CO₂RR coupled oxygen evolution reaction system.

It is well known that transition metal sulfides (TMS) (i.e., NiS₂) undergo electrochemical reconstructions to generate highly active Ni₃S₂ during the process of hydrogen evolution reaction (HER) under overpotentials of < 500 mV. However, at higher overpotentials, Ni₃S₂ can theoretically be further restructured into Ni and thus form Ni/Ni₃S₂ heterogeneous interface structures, which may provide opportunities to further enhance HER activity of NiS₂. Here, we selected NiS₂ as a model electrocatalyst and investigated the influence of the reconstruction results induced from regular to ultrahigh overpotentials on its electrocatalytic hydrogen precipitation performance. The experimental results showed that the most significant enhancement of hydrogen precipitation performance was obtained for the NiS₂@CC-900 (900 means 900 mV overpotential) sample after the ultra-high overpotential induced reconstruction. Compared with the initial overpotential of 161 mV (10 mA cm^-2), the overpotential of the reconstructed sample reduced by 67 mV (42%). The characterization results showed that an ultra-high overpotential of 900 mV induced deep reconstruction of NiS₂, formed highly reactive Ni/Ni₃S₂ heterogeneous interfaces, which is more conducive to improved HER performance and match well with theoretical calculations results. We demonstrated ultrahigh overpotential was an effective strategy to induce NiS₂ deeply reconstruction and significantly improve its HER performance, and this strategy was also applicable to CoS₂ and FeS₂. This study provides an extremely simple and universal pathway for the reasonable construction of efficient electrocatalysts by induced TMS deeply reconstruction.

The catalyst's structural dynamics under reaction conditions critically determine their performance. We proved this indication by studying Ni nanoparticles supported on Mo₂CT_x MXene, where the average size during CO₂ hydrogenation changed from 12.9 to 3.1 nm. A parallel increase of CO selectivity from 21.1% to 92.6% at 400 °C was observed, while the CO₂ conversion rate remained at about 84.0 mmol·g_cat^-1·h^-1. This transformation involved partial removal of Mo₂CT_x terminal groups, allowing direct interaction between Ni and Mo atoms instead of indirect coupling through -O terminations. The shift from a Ni-O-Mo to a Ni-Mo interaction enhanced electron transfer from Ni to Mo₂CT_x, strengthening the metal-support interaction and driving Ni nanoparticle dispersion. In-situ mechanistic analysis and kinetic isotope studies revealed that Ni dispersion suppresses the formate and carboxyl pathway, promotes direct CO₂ dissociation, and inhibits CO hydrogenation, shifting the primary product from CH₄ to CO. These findings provide a strategy for designing highly selective and stable MXene-based catalysts through engineered metal-support interactions.

The development of advanced support is conducive to promoting the practical application of fuel cells but remains an enormous challenge in terms of stabilizing catalyst particles and enabling improved accessibility to O₂. Beyond solid carbon black and conventional porous carbon, we demonstrate a new type of mesoporous bowl-like carbon support with a high specific surface area of over 1200 m² g^-1 and ~ 4 nm pore. Both rotating disk electrode and membrane electrode assembly (MEA) tests show that BC-supported Pt₃Co (Pt₃Co/BC) catalyst greatly outperforms hollow porous carbon spheres and solid carbon spheres supported Pt₃Co catalysts. The Pt₃Co/BC catalysts exhibited remarkable performance as cathode catalyst in MEA, achieving a comparable open-circuit voltage of approximately 0.95 V under H₂-air condition and a current density of 1.3 A cm^-2 at 0.6 V with a loading of only 0.2 mg_Pt cm^-2. Diffusion simulations and physical characterizations demonstrate that the high porosity and highly accessible pore structure of BC support facilitate the uniform distribution of catalyst particles and enhance the mass transport of O₂, thereby resulting in a significant improvement in catalytic activity and durability. This work provides new insights into the influence of support shape on mass transport of reactants and electrochemical performances of the catalyst in MEA.

Active and poisoning-resistant Ru-based electrocatalysts for the hydrogen oxidation reaction (HOR) are designed and fabricated by integrating Cu/Ru dual single atoms and alloy CuRu nanoparticles (N-(CuRu)_NP+SA@NC) through a strategy involving weak chemical reduction and ammonia-assisted gas-phase nitridation. The resultant N-(CuRu)_NP+SA@NC electrocatalysts feature nitrogen atoms coordinated to both Cu and Ru metal atoms via strong N-metal interactions. Density functional theory calculations revealed that alloyed CuRu nanoparticles and monodispersed Cu atoms are vital for altering the electronic configuration of the host Ru elements. This finely tuned structure enhanced the adsorption of H and OH and promoted CO oxidation over the N-(CuRu)_NP+SA@NC electrocatalyst, resulting in high alkaline HOR activity, as evidenced by the higher exchange current density of 3.74 mA cm^-2 and high mass activity of 3.28 mA μg_Ru^-1, which are far superior to those of most Ru-based catalysts reported to date. Moreover, the N-(CuRu)_NP+SA@NC electrocatalysts are resistant to CO poisoning and can be used at a high concentration of 1000 ppm CO with no distinct decay in the activity, in stark contrast to the commercial Pt/C catalyst under the same conditions.

Developing efficient and stable non-precious metal catalysts is essential for replacing platinum-based catalysts in polymer electrolyte membrane fuel cells (PEMFCs). The transition metal and nitrogen co-doped carbon electrocatalyst (M-N-C) is considered an effective alternative to precious metal catalysts. However, its relatively poor performance in acidic environments has always been a problem plaguing its practical application in PEMFCs. This study presents a sequential deposition methodology for constructing a composite catalytic system of Fe-N-C and ionic liquid (IL), which exhibits improved performance at both half-cell and membrane electrode assembly scales. The presence of IL significantly inhibits H₂O₂ production, preferentially promoting the 4e^- O₂ reduction reaction, resulting in improved electrocatalytic activity and stability. Additionally, the enhanced PEMFC performance of IL containing electrodes is a direct result of the improved ionic and reactant accessibility of the pore confined Fe-N-C catalysts where the IL minimizes local resistive transport losses. This study establishes a strategic foundation for the practical utilization of non-precious metal catalysts in PEMFCs and other energy converting technologies.

Potassium (K) is known to enhance the catalytic performance of Fe-based catalysts in the reverse water-gas shift (rWGS) reaction, which is highly relevant during Fischer-Tropsch (FT) synthesis of CO₂-H₂ mixtures. To elucidate the mechanistic role of K promoter, we employed density functional theory (DFT) calculations in conjunction with microkinetic modelling for two representative surface terminations of Hägg carbide (χ-Fe₅C₂), i.e., (010) and (510). K₂O results in stronger adsorption of CO₂ and H₂ on Hägg carbide and promotes C-O bond dissociation of adsorbed CO₂ by increasing the electron density on Fe atoms close to the promoter oxide. The increased electron density of the surface Fe atoms results in an increased electron-electron repulsion with bonding orbitals of adsorbed CO₂. Microkinetics simulations predict that K₂O increases the CO₂ conversion during CO₂-FT synthesis. K₂O also enhances CO adsorption and dissociation, facilitating the formation of methane, used here as a proxy for hydrocarbons formation during CO₂-FT synthesis. CO dissociation and O removal via H₂O compete as the rate-controlling steps in CO₂-FT.

As one of the most important industrially viable methods for carbon dioxide (CO₂) utilization, methanol synthesis serves as a platform for production of green fuels and commodity chemicals. For sustainable methanol synthesis, In₂O₃ is an ideal catalyst and has garnered significant attention. Herein, cubic In₂O₃ nanoparticles were prepared via the precipitation method and evaluated for CO₂ hydrogenation to produce methanol. During the initial 10 h of reaction, CO₂ conversion gradually increased, accompanied by a slow decrease of methanol selectivity, and the reaction reached equilibrium after 10-20 h on stream. This activation and induction stage may be attributed to the sintering of In₂O₃ nanoparticles and the creation of more oxygen vacancies on In₂O₃ surfaces. Further experimental studies demonstrate that hydrogen induction created additional oxygen vacancies during the catalyst activation stage, enhancing the performance of In₂O₃ catalyst for CO₂ hydrogenation. Density functional theory calculations and microkinetic simulations further demonstrated that surfaces with higher oxygen vacancy coverages or hydroxylated surfaces formed during this induction period can enhance the reaction rate and increase the CO₂ conversion. However, they predominantly promote the formation of CO instead of methanol, leading to reduced methanol selectivity. These predictions align well with the above-mentioned experimental observations. Our work thus provides an in-depth analysis of the induction stage of the CO₂ hydrogenation process on In₂O₃ nano-catalyst, and offers valuable insights for significantly improving the CO₂ reactivity of In₂O₃-based catalysts while maintaining long-term stability.

Direct converting carbon dioxide (CO₂) and propane (C₃H₈) into aromatics with high carbon utilization offers a desirable opportunity to simultaneously mitigate CO₂ emission and adequately utilize C₃H₈ in shale gas. Owing to their thermodynamic resistance, converting CO₂ and C₃H₈ respectively remains difficult. Here, we achieve 60.2% aromatics selectivity and 48.8% propane conversion over H-ZSM-5-25 via a zeolite-catalyzing the coupling of CO₂ and C₃H₈. Operando dual-beam FTIR spectroscopy combined with ¹³C-labeled CO₂ tracing experiments revealed that CO₂ is directly involved in the generation of aromatics, with its carbon atoms selectively embedded into the aromatic ring, bypassing the reverse water-gas shift pathway. Accordingly, a cooperative aromatization mechanism is proposed. Thereinto, lactones, produced from CO₂ and olefins, are proven to be the key intermediate. This work not only provides an opportunity for simultaneous conversion of CO₂ and C₃H₈, but also expends coupling strategy designing of CO₂ and alkanes over acidic zeolites.

Propane dehydrogenation (PDH) has emerged as a key on-purpose technology for the production of propylene, but it often depends on toxic chromium and expensive platinum catalysts, highlighting the need for environmentally friendly and cost-effective alternatives. In this study, we developed a facile impregnation method to fabricate unsaturated Co single-atoms with a tricoordinated Co₁O₃H_x structure by regulating silanol nests in purely siliceous Beta zeolites. Detailed PDH catalytic tests and characterizations revealed a positive correlation between the presence of silanol nests and enhanced catalytic activity. Additionally, the unsaturated Co single-atoms exhibited a carbon deposition rate more than an order of magnitude slower than that of Co nanoparticles. Notably, the optimized Co_0.3%/deAl-meso-Beta catalyst achieved a record-high propylene formation rate of 21.2 mmol_C3H6 g_cat^-1 h^-1, with an exceptional propylene selectivity of 99.1% at 550 °C. Moreover, the Co_0.3%/deAl-meso-Beta catalyst demonstrated excellent stability, with negligible deactivation after 5 consecutive regeneration cycles. This study emphasizes the pivotal role of silanol nests of zeolites in stabilizing and modulating the coordination environment of metallic active sites, providing valuable insights for the design of high-activity, high-stability, and low-cost PDH catalysts.

Iron-Vanadium (FeV) catalyst showed a unique catalytic activity for the selective oxidation of methanol to formaldehyde; however, due to its complex compositions, the identification of catalytic active sites still remains challenging, inhibiting the rational design of excellent FeV-based catalysts. Here, in this work, a series of FeV catalysts with various compositions, including FeVO₄, isolated VO_x, low-polymerized V_nO_x, and crystalline V₂O₅ were prepared by controlling the preparation conditions, and were applied to methanol oxidation to formaldehyde reaction. A FeV_1.1 catalyst, which consisted of FeVO₄ and low-polymerized V_nO_x species showed an excellent catalytic performance with a methanol conversion of 92.3% and a formaldehyde selectivity of 90.6%, which was comparable to that of conventional iron-molybdate catalyst. The results of CH₃OH-IR, O₂ pulse and control experiments revealed a crucial synergistic effect between FeVO₄ and low-polymerized V_nO_x. It enhanced the oxygen supply capacity and suitable binding and adsorption strengths for formaldehyde intermediates, contributing to the high catalytic activity and formaldehyde selectivity. This study not only advances the understanding of FeV structure but also offers valuable guidelines for selective methanol oxidation to formaldehyde.

Defect engineering improves the catalytic performance of metal-organic frameworks (MOFs) loaded metal nanoparticles (MNPs@MOFs), but there is still a challenge in defining the structure-activity relationships. Herein, the content of linker-missing defects in UiO-66(Ce) was systematically regulated via formic acid as the modulators, and defective UiO-66(Ce) loaded Ni nanoparticles (NPs) were constructed for dicyclopentadiene (DCPD) hydrogenation. The fine regulation of defect engineering and reduction conditions affected the structure properties of UiO-66(Ce) and the electronic metal-support interaction between MOFs and Ni NPs, thereby optimizing the microenvironment and electronic state of Ni NPs. The optimized U(Ce)-40eq with suitable defects, small size and structure stability effectively promoted the production of highly dispersed abundant electron-deficient Ni⁰ active sites, enhancing the adsorption and activation of H₂ and C=C bonds, especially accelerating the rate-determining step. Therefore, U(Ce)-40eq loaded 5 wt% Ni NPs achieved DCPD saturated hydrogenation to tetrahydrodicyclopentadiene (70 °C, 2 MPa, 90 min), superior to most high-loading Ni-based catalysts. This work reveals the synergistic mechanism of MOFs defect engineering and electronic structure of Ni NPs, providing effective guidance for the precise preparation of highly efficient and stable MNPs@MOFs heterogeneous catalysts.

Aromatization of light alkanes is a value-added process in both petrochemical and coal chemical industries. Here, single [Ga(OH)]²⁺ ion-exchanged mesoporous hollow-structured ZSM-5 (Ga-MH-ZSM-5) material was prepared, and it shows unprecedented catalytic performance in light alkane aromatization, considering activity, product selectivity and catalytic stability. The average aromatics yields in ethane aromatization at 600 °C and WHSV of 0.8 h^-1 within 28 h and in propane aromatization at 580 °C and WHSV of 1.1 h^-1 within 20 h reach ’18.4% and ’70.8% with benzene, toluene and xylenes (BTX) accounting for ’96% and ’88% of aromatics, respectively. Ga-MH-ZSM-5-0.41 gave a TON for formation of aromatics (TON_aromatics) from propane as high as 57479, whereas the reported catalysts maximally show a TON_aromatics of 5514. This also holds true for ethane aromatization; the TON_aromatics obtained on Ga-MH-ZSM-5-0.41 was ≥ 3845 in contrast to £ 392 on reported non-noble metal catalysts. The catalytic activity of Ga-MH-ZSM-5 highly depends on Ga species structures. [Ga(OH)]²⁺ ions are predominant species at Ga loading ≤ 0.3 wt%, while more [Ga(OH)₂]⁺ and GaO_x oligomers are formed with increasing Ga content. Upon reduction with H₂, [Ga(OH)]²⁺ and [Ga(OH)₂]⁺ are transformed into [GaH]²⁺ and [GaH₂]⁺ species, which show a propane dehydrogenation rate of 300 and 15 times of that of Brønsted acid sites respectively. The light alkanes are mainly dehydrogenated into light olefins on [GaH]²⁺ species, and then, oligomerized and cyclized into (alkyl)cycloalkanes on H⁺ sites, which is followed by possible ring expansion on H⁺ and sequential dehydrogenations into aromatics primarily on [GaH]²⁺.

Propylene, a readily accessible and economically viable light olefin, has garnered substantial interest for its potential conversion into valuable higher olefins through oligomerization processes. The distribution of products is profoundly influenced by the catalyst structure. In this study, Fe₂O₃-doped NiSO₄/Al₂O₃ catalysts have been meticulously developed to facilitate the selective trimerization of propylene under mild conditions. Significantly, the 0.25Fe₂O₃-NiSO₄/Al₂O₃ catalyst demonstrates an enhanced reaction rate (48.5 mmol_C3/(g_cat.·h)), alongside a high yield of C9 (~ 32.2%), significantly surpassing the performance of the NiSO₄/Al₂O₃ catalyst (C9: ~24.1%). The incorporation of Fe₂O₃ modifies the migration process of sulfate ions, altering the Lewis acidity of the electron-deficient Ni and Fe sites on the catalyst and resulting a shift in product distribution from a Schulz-Flory distribution to a Poisson distribution. This shift is primarily ascribed to the heightened energy barrier for the β-H elimination reaction in the C6 alkyl intermediates on the doped catalyst, further promoting polymerization to yield a greater quantity of Type II C9. Furthermore, the validation of the Cossee-Arlman mechanism within the reaction pathway has been confirmed. It is noteworthy that the 0.25Fe₂O₃-NiSO₄/Al₂O₃ catalyst exhibits remarkable stability exceeding 80 h in the selective trimerization of propylene. These research findings significantly enhance our understanding of the mechanisms underlying olefin oligomerization reactions and provide invaluable insights for the development of more effective catalysts.

Amines represent fundamental motifs in various chemical contexts and are widely used in agrochemicals and pharmaceuticals. The development of earth-abundant metal-based heterogeneous catalysts for the synthesis amines remains an important goal in terms of chemical research and industrial application/manufacture. Herein, we developed an efficient and highly selective nitrogen-doped nickel catalyst enriched with Lewis acid sites, which has been applied for to the hydrogenative coupling of nitriles and amines with molecular hydrogen for the synthesis of a train of functionalised and structurally diverse secondary and tertiary amines. Furthermore, catalytic hydrogenation and deuteration of nitriles were achieved under milder conditions, yielding a series of primary amines and deuterated amines with high deuterium incorporation.