Active sites are pivotal regions on the surfaces of photocatalysts where interactions with reactants and intermediates occur, governing processes such as adsorption, catalysis, transformation, and desorption. Their regulation is essential for enhancing catalytic performance and achieving high-selectivity product formation. Consequently, identifying and constructing active sites capable of efficiently adsorbing and activating pollutants is a key strategy for improving photocatalytic efficiency. Recently, the identification and classification of active sites across various photocatalysts have attracted increasing attention. A deeper understanding of these sites is pivotal for elucidating catalytic mechanisms, optimizing performance, and guiding the design of more effective catalysts. This review systematically summarizes recent advances in the identification of photocatalytic active sites, highlighting commonly used characterization techniques and their applications in different catalyst systems. The role of these methods in revealing reaction mechanisms is critically discussed, with particular emphasis on the necessity of combining multiple techniques to enhance the reliability of active site identification. Moreover, the limitations of current characterization approaches are analyzed, and future directions for the development of advanced identification strategies are proposed. Improved precision in active site characterization would not only deepen mechanistic insights but also provide theoretical and practical guidance for the advancement of high-efficiency photocatalytic processes.

Photocatalysis provides a viable approach to address critical global challenges of energy scarcity and environmental pollution. Significantly, one-dimensional (1D) nanomaterials (e.g., nanorods, nanowires, nanofibers, nanotubes, and nanobelts) have attracted great attention in the field of photocatalysis owing to their inherent structural advantages such as directional charge transport pathways, high aspect ratio, and abundant exposed active surface sites. Nevertheless, the inherent issue including rapid photogenerated carrier recombination and low apparent quantum efficiency continue to hinder practical implementation of 1D scaffolds. To overcome these limitations, step-scheme (S-scheme) heterojunctions have been strategically constructed using 1D nanomaterials as fundamental building blocks, demonstrating superior charge separation and enhanced photocatalytic properties. In this review, we comprehensively summarized recent advances in the design and implementation of 1D-based S-scheme photocatalysts for targeted applications in sustainable energy conversion, and environmental remediation. The review was introduced by a historical development of the S-scheme charge transfer model and the typical charge transfer mechanism, followed by a comprehensive summary of the preparation approaches and characterization techniques of 1D-based S-scheme systems. Subsequently, a detailed discussion of the recent advances in 1D S-scheme heterojunction photocatalysts for various applications are provided and the implications of the S-scheme charge transfer mechanism on promoting the catalytic activity are elucidated. Finally, the prospects for the development of 1D-based S-scheme heterojunction photocatalysts are presented.

Heterojunction comprising the distinct semiconductors with different band gap and band edge potentials allows the easy migration of charge carriers by utilizing the large fraction of solar light. In this context, the design and fabrication of S-scheme heterojunction (SSH) constituting the oxidation and reduction photocatalysts has spurred interests owing to their flexibility in utilizing the energetic charge carriers for the desired redox reactions that are not only confined to the pollutant degradation reactions and fuel production, but also to extends to broad spectrum of coupled photocatalytic systems. The ZnO is an ideal semiconductor that has the capacity to serve as both oxidation and reduction photocatalyst due to their intermediate band edge positions. In this focused review article, design principles and fabrication of ZnO based S-scheme heterojunction (ZSSH) with various functional semiconductors are discussed under the light of different preparation methods. The mechanism underlying the crystallization, morphological evolution and the heterojunction formation are emphasized. Further improvement in the performance through strategies like co-catalyst modification, doping process, vacancy engineering and fabricating the dual SSH to extend the charge carrier lifetime are underscored. The applications of ZSSH towards various photocatalytic reactions such as H₂ evolution, H₂O₂ production, CO₂ reduction, pollutant degradation and coupled photocatalytic systems are emphasized. Finally, challenges associated in this area are presented to forefront the prospective of this heterostructure for broader visibility in energy-environmental related fields.

Lithium-sulfur (Li-S) batteries, with their ultrahigh theoretical energy density (~2600 Wh·kg^‒1), natural abundance, and low cost represent one of the most compelling next-generation energy storage technologies. However, their practical deployment remains hindered by polysulfide shuttling, sluggish sulfur redox kinetics, severe volume expansion, and limited cycle life. This review provides a comprehensive yet forward-looking analysis of the latest advances in Li-S batteries, emphasizing strategies that go beyond conventional sulfur hosts and electrolytes. Particular attention is given to emerging concepts such as single-atom catalysts, lattice strain engineering, defect modulation, redox mediator-assisted conversion, and high-entropy MXenes, which together offer new opportunities to regulate sulfur electrochemistry. In addition, we highlight the role of artificial solid-electrolyte interfaces and electrolyte optimization in stabilizing Li-metal anodes. By integrating computational insights with experimental breakthroughs, this review not only dissects the mechanistic origins of key challenges but also bridges the gap between laboratory demonstrations and scalable pouch-cell performance. An “Issues at a Glance” framework is introduced to distill the most urgent obstacles and corresponding mitigation strategies. We conclude by outlining a roadmap for translating Li-S research into commercially viable systems. This work aims to serve as both a technical reference and a strategic guide for advancing Li-S batteries toward real-world applications.

The hydroxyethyl radical (•CH(CH₃)OH)-mediated pathway, by avoiding the formation of aldehyde intermediates, constitutes a promising approach for the highly selective photocatalytic synthesis of benzimidazoles from ethanol and o-phenylenediamine. However, inefficient reactant adsorption and activation, as well as severe recombination of photogenerated charge carriers of traditional photocatalysts, impose a fundamental challenge for this reaction pathway. Herein, we construct an oxygen vacancy (V_O)-rich Nb₂O₅ decorated with Pt nanoparticles (NPs), which exhibits the highest photocatalytic activity to date, with production rates of 4.0 mmol g^-1 h^-1 for 2-methylbenzimidazole and 10.2 mmol g^-1 h^-1 for H₂, respectively. The synergistic interaction between V_O and Pt NPs markedly promotes the migration and separation of photogenerated charge carriers. The electron-accumulating Pt NPs drive efficient H₂ evolution through proton reduction, while the engineered V_O sites enhance ethanol adsorption and selectively activate α-C-H bond cleavage to generate •CH(CH₃)OH radicals, suppressing the accumulation of N-ethyl-2-methylbenzimidazole by-products inherent to conventional aldehyde-mediated reaction pathways, significantly facilitating the co-production of benzimidazoles and H₂. This work achieves directional pathway regulation via rational design of semiconductor defects and metal co-catalysts, establishing a radical-mediated strategy for efficient and selective green synthesis of N-heterocyclic compounds.

Efficient and sustainable photocatalytic hydrogen peroxide (H₂O₂) synthesis is crucial due to its role as an eco-friendly oxidant and the limitations of conventional industrial methods. Graphitic carbon nitride (g-C₃N₄) is a promising photocatalyst but suffers from inefficient charge separation and limited visible light absorption. This study introduces a dual-modified g-C₃N₄, incorporating Na⁺/K⁺ ions and cyano groups, coupled with ultrathin BiOCl nanosheets to form an S-scheme heterojunction (CN-NH-NaK/BiOCl). The modification enhances the electronic structure, visible light absorption, and charge separation. The CN-NH-NaK/BiOCl photocatalyst achieved an outstanding H₂O₂ production rate of 33.15 mmol·g^‒1·h^‒1 under visible light (λ ≥ 400 nm), outperforming pristine g-C₃N₄ (118-fold) and BiOCl (83-fold), and surpassing all previously reported g-C₃N₄- and BiOCl-based photocatalysts. Even in pure water, the production rate reached 5.18 mmol·g^‒1·h^‒1, exceeding that of most previously reported catalysts. Comprehensive characterization revealed an efficient S-scheme charge transfer mechanism, enabling selective 2e^‒ oxygen reduction reaction (94.06% selectivity) and water oxidation. The heterojunction demonstrated excellent stability, reusability, and enhanced degradation of tetracycline hydrochloride. This work provides a promising strategy for advanced S-scheme photocatalysts in sustainable H₂O₂ production and environmental remediation.

The conversion of solar energy into hydrogen represents a promising and sustainable approach to addressing the global energy crisis and mitigating environmental pollution. However, achieving the industrial benchmark of solar-to-hydrogen efficiency remains challenging due to the inherently insufficient spatial separation of charge carriers and sluggish interfacial kinetics. Engineering redox-active sites has emerged as an effective approach to enhance photocatalytic hydrogen evolution performance. Herein, a dual-mode copper-modified titanium dioxide photocatalyst (Cu/TiO₂), comprising isolated Cu atoms and CuO nanoclusters, was successfully synthesized via a facile molten salt method. The optimized Cu/TiO₂ exhibited a remarkable hydrogen evolution rate of 37.6 mmol g^-1 h^-1 with methanol as a sacrificial agent, representing a 96-fold enhancement compared to pristine TiO₂. Mechanistic studies revealed that isolated Cu atoms incorporated into the TiO₂ lattice substantially lower the free energy of hydrogen adsorption (*H), thereby promoting the proton reduction half-reaction. Simultaneously, the surface-dispersed CuO nanoclusters were found to reduce the overpotential for methanol oxidation, thereby accelerating the oxidation half-reaction and facilitating overall charge balance during photocatalysis. Furthermore, photocatalytic hydrogen production coupled with the oxidation of various organic molecules was evaluated under a low sacrificial agent concentration (0.1%) over the Cu/TiO₂ photocatalyst, offering a more sustainable and practically relevant assessment of catalyst performance for green energy applications.

The photocatalytic conversion of nitrate (NO₃^-) into ammonia (NH₄⁺) under mild conditions offers a promising approach for mitigating environmental nitrate contamination. The efficiency of this process is fundamentally governed by the adsorption and activation of NO₃^- and its intermediates, which are significantly influenced by the surface electronic properties of the catalyst, particularly the position of the d-band center. However, conventional approaches to tune the surface electronic structure such as doping with extraneous elements or forming heterojunctions often alter the overall band structure seriously, typically leading to reduced photocatalytic activity. In this study, the d-band state of (CuGa)_xZn_1‒2xGa₂S₄ semiconductor is engineered through Al³⁺ surface decoration without affecting the conduction band or the bandgap to enhance NO₃^- adsorption and activation. X-ray photoelectron spectroscopy and X-ray absorption fine structure analyses reveal that the surface doping of Al³⁺ do not induce obviously energy band structure change but the d-band center, which shift more closer to Fermi level in comparison with pristine material. Electronic energy band analyses indicate that Al³⁺ decoration does not significantly alter the conduction band or bandgap. Moreover, the Al³⁺-modified material demonstrates a substantial improvement in photocatalytic conversion of NO₃^- into NH₄⁺, increasing the NH₄⁺ production rate from 0.18 to 0.93 mmol h^-1 g^-1. Density functional theory calculations further revealed that the d-band center of Al³⁺/(CuGa)_xZn_1-2xGa₂S₄ shifted closer to the Fermi level, moving from -4.75 to -4.54 eV compared to the pristine (CuGa)_xZn_1-2xGa₂S₄. This shift lowered the Gibbs free energy for the adsorption of NO₃^- reduction intermediates, thereby enhancing the conversion efficiency of NO₃^- into NH₄⁺. This work introduces an effective strategy for surface d-band states modulation without altering the intrinsic band structure to improve nitrate reduction performance, offering deep insights into the future design of materials for environmental remediation applications.

Solar-driven CO₂ reduction is confronted with challenges of limited light absorption and elevated reaction energy barriers. To address these, a solvothermal-wet coupled chemical reduction method was developed to precisely construct a bifunctional catalyst comprising single-atom Ru and clustered Ni on porous CeO₂ nanorods, featuring efficient CO₂ methanation in H₂O vapor under concentrated solar irradiation (4.01 W·cm^-2). Through lattice substitution at Ce sites, Ru single atoms form a distinctive pentacoordinate configuration, largely accelerating H₂O dissociation to generate active hydrogen (^*H). Conversely, Ni clusters enhance visible-to-near-infrared light capture via localized surface plasmon resonance effects, optimizing the CO₂ adsorption configuration to reduce the activation energy barrier of the C=O bond. The synergistic interplay between these dual sites, mediated by the hydrogen spillover effect, resolves the spatiotemporal mismatch between proton supply and carbon source activation. Based on the evidence from femtosecond and nanosecond transient absorption spectroscopy, the Ru/Ni dual-active sites enable spatially decoupled directional transport of charge carriers, synergistically handling the photogenerated carrier transfer dynamics. Furthermore, the robust photoelectric and thermal effects induced by concentrated irradiation enhance photogenerated carrier concentrations and the reaction temperature, reducing the apparent activation energy for CH₄ formation to 14.61 kJ·mol^-1 (a 29.9% decrease compared to non-concentrated systems). This catalyst achieves a CH₄ production rate of 133.1 μmol·cm^-2·h^-1 (a 31-fold enhancement over non-concentrated systems) and a solar-to-chemical energy conversion efficiency of 0.423%, offering insights into the design of photothermal synergistic catalytic systems through atomic-scale active site decoupling and multi-physical field coupling.

Societal and industrial development has caused a drastic increase in greenhouse gas emissions, leading to serious environmental problems. One-carbon (C1) based biomanufacturing offers a green and sustainable approach for converting C1 compounds such as carbon dioxide (CO₂) to biofuels and biochemicals. However, the efficiency of C1-based biomanufacturing is still challenging, due to the intrinsic inefficiency of C1-utilizing pathways and the inadequate supply of energy and reducing power. Here, a light-driven biohybrid system (LDBS) was developed to facilitate energy-efficient bioproduction by integrating reducing power regeneration and synthetic C1 fixation modules in E. coli. Reducing power regeneration module was constructed by biosynthesizing photosensitive cadmium selenide quantum dots in E. coli to enable the conversion of solar energy to reducing power, leading to a 148.1% increase in intracellular NADH contents. C1 fixation module was built by employing a new-to-nature serine aldolase/malic enzyme cycle. By integrating two modules, LDBS was programmed in a plug-and-play manner for the biosynthesis of C2, C3 and C4-compounds with C1 utilization rates approaching those of cyanobacteria and microalgae. The study demonstrates a carbon-negative platform that extends the operational scope of photobiosynthesis technologies, potentially advancing C1-based biomanufacturing for sustainability.

The selective cleavage of C_α-C_β bonds is of great significance to lignin valorization, and photocatalysis offers an eco-friendly pathway to achieve this process. Here, graphitic carbon nitride (g-C₃N₄) modified with hollow tubular In₂O₃ was constructed via the calcination method for the photocatalytic cleavage of lignin C_α-C_β bonds. MIL-68(In) was used as the precursor of In₂O₃, imparting a unique hollow tubular structure and a relatively large specific surface area. The hollow tubular structure is helpful for light penetration and scattering, as well as rapid migration of the lignin substrate. The Z-scheme g-C₃N₄/In₂O₃ heterojunction exhibited 92.1% conversion (corresponding benzaldehyde yield: 82.4%) of the lignin model compound 2-phenoxy-1-phenylethanol (PP-ol), outperforming pure In₂O₃ and g-C₃N₄ by 40- and 2.3-fold, respectively, under 395 nm light illumination. By varying the illumination wavelength, the conversion and yields of the g-C₃N₄/In₂O₃ composites were found to follow wavelength-dependent reactivities. Additionally, photogenerated holes are capable of converting PP-ol into benzoic acid, whereas ¹O₂ mainly converts PP-ol into benzaldehyde. This work could encourage the application of metal-organic frameworks in biomass conversion and provide insight into photocatalytic lignin valorization.

The persistent challenge impeding photocatalytic advancement lies in achieving simultaneous efficient utilization of photogenerated carriers for dual value-added reactions. This study demonstrates the synergistic interplay of plasmon-exciton-phonon interactions within non-metallic plasmonic Mo₂N quantum dots anchored on ultrathin ZnIn₂S₄ nanosheets (0D/2D Mo₂N/ZnIn₂S₄), which simultaneously enhances photocatalytic hydrogen evolution and selective oxidation of 4-methoxybenzyl alcohol to 4-methoxybenzaldehyde. Integrated experimental, operando spectroscopic, and theoretical analyses reveal triple cooperative mechanisms: localized surface plasmon resonance at Mo₂N sites generates high-energy hot electrons through plasmon-exciton coupling, significantly reducing the apparent activation energy to 4.87 kJ·mol^-1; quantum confinement synergizing with the 0D/2D ohmic-junction concentrates excitons at nanoscale interfaces, enabling prolonged carrier lifetime; meanwhile, directional photon-to-phonon energy conversion induces uniform photothermal heating (ΔT = 55.9 °C), kinetically accelerating dehydrogenation while balancing redox half-reactions. This synergy achieves sacrificial-free co-production rates of 96.3 mmol·h^-1·g^-1 H₂ and 38.7 mmol·h^-1·g^-1 4-methoxybenzaldehyde with 13.7% apparent quantum efficiency at 420 nm, establishing a new paradigm for solar-driven chemical refineries via precision plasmon-phonon engineering.

Polystyrene, a widely used yet chemically inert plastic, poses major recycling challenges due to its low degradability and global recovery rate below 1%, calling for innovative upcycling strategies under mild conditions. Herein, we report a dual-functional ionic liquid catalyst, [BSPy][OTf]-Fe(OTf)₃, that enables room-temperature photooxidative upcycling of PS into benzoic acid with a yield of 76.43% in 24 h under an oxygen atmosphere. This catalytic performance is substantially higher than that of control systems using individual components or their physical mixture, indicating a strong synergistic effect. Mechanistic investigations revealed that Fe³⁺ in the ionic liquid initiates chain scission via a single-electron transfer process, generating oxidized intermediates. These intermediates are subsequently converted to benzoic acid through singlet oxygen, as supported by kinetic isotope effect studies and density functional theory calculations. The generation of singlet oxygen is facilitated by the ionic liquid catalyst, as confirmed by ultraviolet-visible and electron paramagnetic resonance spectroscopy. The approach is applicable to post-consumer Polystyrene products, with benzoic acid yields ranging from 56.01% to 74.57%. This study establishes a mechanistically guided strategy for low-energy, selective upcycling of PS, offering a viable alternative to conventional high-temperature or harsh-oxidant approaches.

Solar-driven CO₂ conversion into valuable hydrocarbon fuels process primarily depends on the development of efficient photocatalysts capable of achieving effective charge separation, high sunlight utilization, and strong reactant adsorption. In this work, one-dimensional (1D) TiO₂ nanobelts with abundant oxygen vacancies (TN) were strategically coupled with a two-dimensional (2D) electron-rich triazine-based covalent organic framework (CTF) to construct a high-efficiency 1D/2D TN/CTF S-scheme heterojunction for photocatalytic CO₂ reduction. The resulting TN/CTF composites exhibited impressive CO₂ conversion rates toward CO and CH₄ generation, with the optimized TN/CTF composite (TN/CTF10) achieving the highest CO and CH₄ yields of 21.4 and 7.9 μmol g^‒1 h^‒1, respectively, which were 3.5- and 4.4-fold higher than those of pristine CTF and represented 6.5- and 7.2-fold enhancements compared to pure TN. The charge-transfer mechanism involved in the S-scheme heterojunction was identified via photo-irradiated Kelvin probe force microscopy, in-situ X-ray photoelectron spectroscopy, and density functional theory calculations, while the formation of oxygen vacancies was confirmed by electron spin resonance and X-ray photoelectron spectroscopy. Further in-depth studies indicate that the oxygen vacancies in TN greatly broaden light absorption and provide an intermediate energy level that accelerates charge separation in the S-scheme heterojunction, thereby significantly improving light-harvesting efficiency and suppressing charge recombination. Meanwhile, the synergistic integration of defect engineering with S-scheme heterojunction design optimizes redox capability and CO₂ adsorption strength to enhance the CO₂ reduction reaction. This work offers a new perspective on designing high-performance photocatalysts by integrating defect engineering into S-scheme heterojunctions.

Electrocatalytic nitrite reduction represents a sustainable and efficient alternative to conventional routes for the production of hydroxylamine and ammonia. A comprehensive understanding of the correlation between the nature of catalytic active sites and their electrocatalytic performance is essential, particularly in steering product selectivity. Herein, we report the synthesis of a series of highly crystalline metalated porphyrin-based covalent organic frameworks (M-TAPP-TTF COFs, M = Zn, Fe), enabling systematic investigation of the structure-selectivity relationships and mechanistic pathways dictated by distinct metallic centers during NO₂RR. Experimental evaluations reveal that fully metalated Zn-porphyrins in COFs could efficiently inhibit the deep reduction of NO₂^- to NH₃ even at higher potentials, with NH₂OH as the major product throughout the entire voltage window. The maximum Faradaic efficiency of NH₂OH (FE_NH2OH) is 71.4% and its yield rate could reach up to 542.3 μmol h^-1 mg_COF^-1 at -2.0 V vs. Ag/AgCl. Meanwhile, when the metallic centers in the porphyrins were switched to Fe ions, it exhibits superior selectivity toward NH₃ formation, achieving a maximum FE_NH3 of 72.6% and a yield rate of 867.2 μmol h^-1 mg_COF^-1 at -2.0 V vs. Ag/AgCl. Complementary density functional theory calculations and in-situ Raman spectroscopy reveal that the Zn active sites in Zn-TAPP-TTF COF promote the preferential hydrogenation of *NO to *NHO, followed by the thermodynamically favorable desorption of NH₂OH, thereby enhancing selectivity toward NH₂OH. In contrast, Fe active sites in Fe-TAPP-TTF COF favor the *NO to *NOH pathway, in which *NOH undergoes further reduction via N‒O bond cleavage with following favorable desorption of NH₃. These insights into metallic site-dependent reaction pathways offer a mechanistic basis for the rational design of single-atom catalysts with tunable selectivity in electrocatalytic NO₂RR.

The photogenerated carrier separation efficiency and material wettability are of critical importance for aqueous-phase photocatalytic reactions, achieving both simultaneously poses a significant challenge owing to the inherent interdependencies and trade-offs involved. In this work, a series of isoreticular benzotrithiophene-based covalent organic frameworks (COFs) were successfully synthesized by incorporating diverse hydrophobic and hydrophilic functional groups (-OH, -F, -H) onto their skeletons, thereby modulating their characteristic charge separation and transport as well as their wettability, and systematically studied their photocatalytic H₂O₂ production performance in O₂-saturated water under visible-light irradiation. Remarkably, the synthesized hydrophilic BTT-BD-OH-COF demonstrates the highest H₂O₂ production rate of 6105 μmol g^-1 h^-1 in the absence of any sacrificial agent in pure water, attributed to its extended light absorption range, improved hydrophilicity, and enhanced photo-induced charge separation and transport efficiency. Combined experimental results and the density functional theory calculations elucidate the reaction mechanism, revealing the overall H₂O₂ photosynthesis via both oxygen reduction reaction and water oxidation reaction dual pathways. This study demonstrates that functional-group-mediated linker engineering is a powerful approach for significantly enhancing the efficiency of COF-based photocatalysts.

Covalent organic frameworks (COFs) have garnered considerable attention for their potential in photocatalytic hydrogen peroxide (H₂O₂) generation. However, their limited photocatalytic efficiency, resulting from rapid photogenerated carrier recombination and weak oxygen adsorption, remains a critical challenge, especially in systems without sacrificial agents. Herein, we present a cyano-functionalized COF, BTT-CN-COF, synthesized by Schiff-base condensation of benzotrithiophene-2,5,8-tricarbaldehyde and 2,5-diaminobenzonitrile monomers. Incorporating the electron-withdrawing cyano groups into the COF creates a strongly polarized microenvironment that redistributes π-electron structure. This modulation enhances material hydrophilicity, reduces exciton binding energy to accelerate charge separation, prolongs photogenerated carrier lifetime, and favors a Yeager-type oxygen adsorption configuration, thereby enhancing photocatalytic performance. Consequently, BTT-CN-COF achieves an impressive H₂O₂ production rate of 3711 μmol g⁻¹ h⁻¹ under sacrificial-agent-free conditions and retains high stability for at least 20 h, surpassing the cyano-free analogue COF (BTT-Ph-COF) and numerous reported COF-based photocatalysts. Mechanism studies reveal that H₂O₂ generation primarily proceeds via a sequential two-step single-electron oxygen reduction reaction, accompanied by a direct two-electron water oxidation reaction.

The development of high-performance and durable oxygen reduction reaction catalysts under harsh working environments remains a key challenge in advancing proton exchange membrane fuel cells. Here, we report a series of hollow-structured covalent organic framework-derived carbon as support materials for PtCo alloy nanocatalysts. These hollow architectures provide unique spatial confinement and encapsulation effects, which not only facilitate efficient mass transport but also protect active sites from degradation in acidic media, thereby ensuring simultaneous enhancement in activity and stability. The optimized PtCo@NC_TAPBT catalyst delivers a peak power density of 1.23 W cm^-2 under H₂-Air conditions and a mass activity of 1.06 A mg_Pt^-1 at 0.9 V, representing 2.41 times higher than that of commercial Pt/C (0.40 A mg_Pt^-1). Moreover, the fuel cell assembled with this catalyst exhibits outstanding durability, showing a voltage degradation of only 8 mV after 30000 cycles at 0.8 A cm^-2 and a mass activity retention of 87.7% (0.93 A mg_Pt^-1). Notably, this performance exceeds the U.S. Department of Energy’s 2025 initial mass activity target (0.44 A mg_Pt^-1) by a factor of 2.1, highlighting the potential of HCOF-derived carbon materials for next-generation fuel cell applications.

Pt/C catalysts are widely used for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs) but suffer from limited stability. Herein, we demonstrate that the introduction of Fe-N-C layers onto the surface of Pt/C catalysts can significantly bolster both the ORR stability and activity of Pt/C in the harsh working environment of PEMFCs. Whilst Fe-N-C catalysts typically exhibit poor ORR activity and durability in acidic media, the obtained PtFe/C@Fe-N-C catalyst exhibits a very high peak power density of 2.03 W cm^-2 and an excellent mass activity (MA) of 0.75 A mg_Pt^-1 in a H₂-O₂ fuel cell, with only 2.7% decay after 30000 cycles, far superior to the Pt/C (0.176 A mg_Pt^-1 and 54.0% decay) and the U.S. Department of Energy 2025 targets. Experimental and density functional theory investigations unequivocally confirm that the Pt coated with optimized Fe-N-C layer contributes to a more delocalized electronic structure and stronger bonding between Pt and FeN_x via strong hybridization of 5d-3d/2p orbitals, resulting in the excellent activity and stability of the PtFe/C@Fe-N-C catalyst.

Polymetallophthalocyanine covalent organic frameworks (pMPc-COFs) exhibit considerable promise in the electrocatalytic CO₂ reduction reaction (CO₂RR) due to their tunable active sites and excellent structural stability. Nevertheless, preparation of crystalline pMPc-COFs under mild conditions remains a significant challenge. Herein, we developed a mild and scalable synthetic strategy, which can realize the construction of pMPc-COFs with different metals embedded. Thus, in the presence of different metal atoms (Co, Bi and Cu), the nucleophilic catalyst 4-dimethylaminopyridine (DMAP) flux-mediated formation of pMPc-COFs occurred efficiently leading to crystalline DMAP-pCoPc-COFs, DMAP-pBiPc-COFs and DMAP-pCuPc-COFs, respectively, incorporated with well-defined single-metal-atom reactive centers at a temperature of 150 °C with no other solvents required. Intriguingly, in the electrocatalytic CO₂RR, as-prepared DMAP-pCoPc-COFs demonstrated remarkable CO Faradaic efficiencies above 88% and up to 91% over a wide potential range (-0.8 to -1.0 V vs. RHE). More interestingly, DMAP-pBiPc-COFs, as the first example of Bi phthalocyanine COFs to date, exhibited an encouraging formate selectivity of up to 85%, making it one of the most efficient formate electrocatalysts. The tuning of CO₂RR selectivity by the center metal was further revealed from the atomic level through in-situ infrared spectroscopy technique and theoretical calculations, providing new insights for the design of efficient electrocatalysts involving pMPc-COFs.

Electrocatalytic carbon dioxide reduction (CO₂RR) offers a highly promising strategy for achieving carbon-neutral energy cycles by converting CO₂ into high-value chemicals and fuels. While it remains challenging to modulate the electronic environment precisely and systematically around the active sites of catalysts to steer the reaction toward desired products, especially hydrocarbons such as methanol (CH₃OH). This study reports a strategy that enables highly efficient CO₂RR to CH₃OH under neutral conditions by fine-tuning the electronic environment of cobalt center in cobalt phthalocyanine (CoPc) through nitrogen-rich supports. Among them, CoPc/TiN achieved a high Faradaic efficiency of 53.28% for CH₃OH production at -1.0 V (vs. reversible hydrogen electrode), with a partial current density of 68.76 mA cm^‒2. X-ray photoelectron spectroscopy and extended X-ray absorption fine structure analyses reveal that electronic modulation at Co-N sites of CoPc, which can promote ^*HCO coupling, and it’s a critical step in CH₃OH formation. Theoretical calculations further demonstrate that nitrogen carriers induce electronic redistribution within the Co center coordination environment. The projected density of states of ^*HCO on CoPc loaded on (Si)N-MXene)/TiN/C₃N₄ shown electron deficient characteristics. It promotes the formation of ^*HCO, thereby facilitating CH₃OH synthesis. This work provides new mechanistic insights into CO₂RR for CH₃OH and opens new avenues for designing efficient catalysts.

The dynamic reconstruction of surfaces during electrochemical reactions plays a crucial role in determining the performance of electrocatalysts. However, because reconstructions occur at the atomic level, direct observation and elucidation of the underlying mechanism are challenging for conventional powder-type catalysts with ill-defined lattices. In this study, the catalytically active surface of 3C BaRuO₃ (BRO) epitaxial thin films emerges upon the dynamic introduction of surface Ru clusters, for the alkaline hydrogen evolution reaction (HER). Based on the mass activity at overpotential 100 mV, the intrinsic HER performance increases dramatically from 0.11 to 7.72 A mg_Ru⁻¹ immediately after the initial HER cycle and eventually saturates at 1.05 A mg_Ru⁻¹ after continuous operation. The formation of Ru clusters on the catalyst surface, driven by selective Ba leaching under alkaline HER conditions, is observed experimentally. Density functional theory calculations demonstrate that HER activity increased with enhanced H* adsorption owing to the dynamic Ru₆ cluster formation. A strategy for stabilizing the ‘awakened’ active surface of BRO is further proposed by validating that the atomic-scale control of the film thickness can effectively maintain the highly active state. This study offers fundamental insights into the design and stabilization of the highly active Ru-based electrocatalysts for the alkaline HER.

Photothermal coupling catalytic CO₂/H₂O to CH₄ is recognized as an effective strategy for addressing environmental concerns and energy crisis. However, hydrogen evolution reaction (HER) competition and weak intermediate adsorption limiting CH₄ selectivity and yield during the reaction process. Herein, we incorporate Bi into the In₂O₃ lattice to create an oxygen-bridged asymmetric bimetallic In-O-Bi (In-O-Bi bridge) sites. The optimized Bi/In₂O₃ catalyst achieves CH₄ yield of 214.1 μmol·g^-1 with 96.7% selectivity. The exceptional catalytic activity of Bi/In₂O₃ stems from two key synergistic effects: (1) the cooperative interaction between Bi and In as p-block metals effectively suppress the competing HER, and (2) the unique In-O-Bi bridge configuration induces significant electron delocalization through p-orbital hybridization. This electronic modulation creates highly active catalytic centers, with In sites preferentially facilitating H₂O dissociation while Bi sites selectively promote CO₂ reduction. Moreover, the electron delocalization effect in the In-O-Bi bridge sites enhances the adsorption and electron transfer capabilities of the Bi/In₂O₃ surface for key CHO species, and reduces the energy barrier, thereby enabling efficient CH₄ production. These findings provide crucial insights into the design of photothermal catalysts, highlighting the transformative potential of oxygen-bridged asymmetric bimetallic units in efficient CO₂ methanation and sustainable energy technologies.

Achieving both high activity and long-term stability for the oxygen evolution reaction (OER) in acidic media remains a critical challenge for proton exchange membrane water electrolyzers (PEMWEs). In this study, we proposed a Cu-incorporated ruthenium (Ru) catalyst (CuRu-250) that exhibited superior performance via dynamic surface modulation during operation. Rather than serving solely as a static dopant, Cu actively influenced the catalyst surface by undergoing partial dissolution and inducing surface restructuring. This dynamic behavior enabled pathway tuning from the adsorbate evolution mechanism to the oxide path mechanism, enhancing the intermediate turnover and suppressing the overoxidation of Ru. Consequently, CuRu-250 demonstrated markedly improved durability and competitive activity compared to undoped Ru and commercial RuO₂. Single-cell PEMWE tests validated its catalytic performance under realistic conditions. These findings highlight the role of active dopant behavior in tuning acidic OER pathways and improving electrochemical resilience, thus offering a practical strategy for advanced catalyst design.

Modulating the potent oxidative nature of Pt sites is the central strategy for optimizing the selective catalytic oxidation of NH₃ (NH₃-SCO). The primary challenge is to suppress byproduct formation (N₂O, NO_x) while preserving the intrinsic activity for N₂ production, a balance governed by the metal-support interaction. Herein, a facile physical-mixing strategy is demonstrated to engineer a Pt/Cu-SSZ-13 catalyst that simultaneously establishes a moderate Pt-Cu interaction while preserving the integrity of isolated Z₂Cu sites. This catalyst demonstrates superior performance, achieving 98% NH₃ conversion at 180 °C and over 90% N₂ selectivity (280‒300 °C), outperforming its counterpart prepared by intensive grinding. It also exhibits exceptional hydrothermal stability (750 °C, 10 h). Electronic structure and in-situ spectroscopy results reveal that the Pt-Cu electronic interaction tunes the reactivity of Pt sites to selectively catalyze the formation of *NO_x intermediates. Concurrently, the preserved Z₂Cu sites act as distinct active centers for NH₃ adsorption, which then readily reduce these intermediates to N₂.

Promoting activity while inhibiting hazardous byproduct formation remains a great challenge in oxygenated volatile organic compounds (OVOCs) purification. Here, we found that the low-temperature oxidation of ethyl acetate (EA) and the generation rate of CO₂ were enhanced by controlling the initial Ag precursor (ions vs. nanoparticles) to engineer catalysts with distinct active site configurations. The reaction rate and TOF_Ag of Ag nanoparticles/310MnO₂ (Ag-NP/310MnO₂) are 4.3 and 4.1 times higher, respectively, than those of Ag ions/310MnO₂ (Ag-IS/310MnO₂) at 150 °C. And Ag-NP/310MnO₂ further shows a 1.9-fold higher CO₂ selectivity compared to that of Ag-IS/310MnO₂. The adsorption ability of EA is much stronger than that of O₂ at Ag site, while the opposite trend is observed at oxygen vacancy. The synergy between Ag site (EA adsorption) and oxygen vacancy (O₂ dissociation) in Ag-NP/310MnO₂ accelerates O₂ activation and subsequent EA oxidation. Moreover, abundant active oxygen species (*O) promote the rate-limiting step of acetic acid decomposition, contributing to superior low-temperature CO₂ selectivity. However, due to the fierce competition from EA, limited O₂ is adsorbed at Ag site-occupied oxygen vacancy, which is difficult to dissociate especially at low temperature, leading to inferior activity of Ag-IS/310MnO₂. This work provides a vital scientific basis for enhancing the low-temperature deep oxidation of OVOCs, showcasing remarkable environmental significance.

Sulfur-induced catalyst deactivation has been a challenge in the design of gaseous pollutants purified catalyst. As the mainstream strategy for anti-sulfur catalyst design, the incorporation of sacrificial components into the catalyst bulk still faces issues such as increased cost and rapid activity decline. Herein, the physical isolated island strategy is proposed to improve the sulfur resistance and cost-effectiveness of a lean methane oxidation catalyst at no cost of its high activity. The isolated Al₂O₃ island suppresses the formation of sulfates on adjacent Ir@Pt nanoparticles and avoids the sulfation of Ir@Pt/TiO₂. Meanwhile, the isolated Al₂O₃ island draws little effect on the chemical states of active sites. The sulfur adsorption function of isolated Al₂O₃ island and high activity of Ir@Pt/TiO₂ are synergistically combined, leading to both remarkably high CH₄ oxidation activity (TOF = 1.2 s^‒1 at 350 °C) and high sulfur resistance without observable activity loss during 50 h on-stream test under 50 ppm SO₂ and a space velocity of 30000 mL g^‒1 h^‒1. Such isolated-island strategy provides a meaningful reference for the efficient sulfur resistance catalyst design.

The selective hydrogenation of furfural (FAL) to furfuryl alcohol (FOL) over Ni catalysts offers a sustainable route for biomass valorization. However, the conventional Ni catalysts suffer from poor selectivity in FAL hydrogenation. Herein, we report that the moderate Fe doping in Ni/TiO₂ significantly enhances selectivity without compromising catalytic activity for the selective hydrogenation of FAL to FOL. Notably, Ni/Fe-TiO₂ catalyst with Fe content ≥ 4.9 wt% maintained > 90% selectivity toward FOL at nearly 100% conversion, whereas Ni/TiO₂ achieved only 38% under the identical condition. Combined experimental and theoretical studies revealed that the enhanced catalytic performance of Ni/Fe-TiO₂ originates from the dilution of contiguous Ni sites by Fe, which suppresses the further hydrogenation of FOL. Moreover, Fe sites exhibited a stronger affinity for carbonyl groups compared to Ni(0), indicating complementary role where Ni(0) primarily facilitates H₂ dissociation, while Fe sites play a critical role in carbonyl activation. These findings underscore the superior synergistic effect of bimetallic systems in promoting selective functional group transformation.

Single-atom catalysts possess the ability to effectively modulate the chemical environment of active sites, thereby synergistically enhancing catalytic reaction activity due to their unique electronic properties. In this study, single-atom Ni-doped CeO₂-supported Pd catalysts were designed and synthesized. The introduction of single-atom Ni induced lattice distortion in the CeO₂ support, resulting in an increased concentration of oxygen vacancies on the surface. This increase in oxygen vacancies enhances the strong metal-support interactions between Pd and the support. Under the intensified metal-support interaction effect, Pd species tend to transfer more electrons to Ni atoms and adjacent O atoms, leading to a higher proportion of high oxidation states (Pd⁴⁺) in PdO_x species. The presence of high-valent Pd⁴⁺ and oxygen vacancies synergically enhances the activation of C-H bonds in methane and the adsorption and dissociation of oxygen, significantly improving the overall catalytic activity of methane combustion. This study provides a critical theoretical foundation and practical guidance for the design and optimization of clean energy catalysts.

The development of highly efficient and stable non-precious metal catalysts under mild conditions is highly desirable for NH₃ synthesis. However, the competitive adsorption of N₂ and H₂ on the single site and strong NH₃ adsorption greatly hinder the catalytic efficiency of catalysts under mild conditions. Herein, we propose the use of responsive alkali metal perrhenates (AMReO₄, AM = K, Na, or Cs) supports with scheelite-type structure that contains active Re metal and promoters to disperse cobalt (Co) species, constructing highly efficient catalysts by regulating the competitive reactant adsorption-activation pattern to a non-competitive mechanism. Our studies demonstrate that Co/KReO₄ catalyst shows excellent catalytic performance for NH₃ synthesis. Co and Re sites synergistically to promote the activation of N₂ molecules, while the adsorption and activation of H₂ primarily occur on Re sites of KReO₄. The presence of Co species facilitates H-spillover that enables the migration of *H species from Re to Co sites, then cascade catalysis of hydrogen and dissociated nitrogen species to form NH₃. Accordingly, the NH₃ synthesis rate of Co/KReO₄ (11.48 mmol_NH3 g_cat^-1 h^-1) is 3.2-fold higher than that of KReO₄ (3.58 mmol_NH3 g_cat^-1 h^-1) at 400 °C and 1 MPa. This work emphasizes the significance of employing reactive supports containing promoters and active metals, in collaboration with non-precious Co sites, to enhance NH₃ synthesis performance under mild conditions.