The efficient and simultaneous utilization of photogenerated electrons and holes in photocatalytic reduction-oxidation (redox) reactions is currently an important trend in photocatalysis. This review systematically describes photocatalytic redox systems involving H2 evolution, H2O2 evolution, CO2 reduction, and NO3- reduction coupled with key oxidation reactions, respectively, to meet economic and sustainable goals. The general background and fundamental principles of photocatalytic coupled reactions are first introduced to provide a systematic understanding of the field. Thereafter, the research progress of H2 evolution, H2O2 evolution, CO2 reduction, and NO3- reduction coupled with various oxidation reactions, including H2O oxidation, biomass and its derived platform molecules valorization, organics conversion, and pollutants treatment, respectively, is highlighted. Moreover, the commonalities and differences among photocatalytic coupled reactions are briefly summarized. Finally, the remaining challenges and future prospects of photocatalytic coupled reactions are critically discussed.

Strongly endothermic reactions are always constrained by thermodynamic equilibrium that necessitates high-temperature operation. This paper describes a co-thermal coupling strategy that integrates two thermodynamic equilibrium-limited processes into a single reaction environment via hydrogen transfer. In this system, the hydrogen generated in situ from endothermic propane dehydrogenation is continuously consumed by simultaneous carbonate decomposition, thereby achieving bidirectional reaction intensification. As a result, the decomposition temperature of calcium carbonate is reduced by approximately 75 °C compared to inert conditions, while the propane dehydrogenation conversion reaches ~120% of the thermodynamic equilibrium value with a propylene selectivity of 97.8% during the continuous regeneration cycles. In situ spectroscopic and kinetic analyses demonstrate a coupled reaction network, where hydrogen transfer promotes carbonate transformation via bicarbonate-related surface intermediates and then follows the reverse water-gas shift pathway. Techno-environmental analysis indicates that this integrated process lowers the energy consumption per ton of propylene by 9.8% and reduces net CO2 emissions by 18.1% in the base-case industrial simulation, while co-producing propylene and a CaO-containing solid. These findings establish hydrogen-mediated co-thermal coupling as a general strategy for surmounting equilibrium constraints and intensifying energy- and carbon-intensive chemical processes. Thermodynamic equilibrium imposes a major limitation on strong endothermic reactions, requiring energy-intensive high-temperature operation. Here, the authors develop a co-thermal coupling strategy that links two equilibrium-limited processes through hydrogen transfer in a single reaction environment, achieving bidirectional reaction intensification.

Direct hydrogenation of carbon dioxide (CO2 ) to acetic acid, a key commodity chemical, offers a sustainable route to valorize greenhouse gases but is plagued by CO2 inertness, thermodynamic barriers, and poor selectivity for C-C coupling over competing overhydrogenation. This paper describes the design and synthesis of ultrathin cobalt(II) oxide nanosheets (<4 nm thick) that achieve direct one-step CO2 hydrogenation to acetic acid with over 90% selectivity, minimal C1 by-products and the highest reported yield under mild conditions, surpassing traditional multistep routes (such as CO2 to CO/methanol followed by carbonylation) in cost, efficiency, and atom economy. These two-dimensional structures feature extended terraces that undergo in situ reconstruction in CO2/H2 mixtures to a cobalt(II) carbonate hydroxide-like phase, stabilizing Co2+ and generating abundant hydroxyl groups to optimize CO2 activation and selective C-C coupling while suppressing over-reduction. In situ characterizations, including electron energy-loss near-edge structure, spatially resolved infrared spectroscopy, and kinetic/isotopic analyses, reveal the reconstructed phase's role in modulating electron density for superior yields and confirm a formate-coupling mechanism unattainable with conventional catalysts. This study introduces a paradigm for CO2 upgrading: harnessing dynamic surface reconstructions and nanoscale morphology to access elusive multicarbon pathways, with implications for sustainable chemical synthesis.

γ-Al2O3 is one of the most widely used catalyst supports in heterogeneous catalysis, yet its catalytic role remains unclear due to intrinsic structural disorder and complex surface species. This paper describes the development of a high-accuracy Al–O–H machine learning interatomic potential combined with global optimization to explore the structural landscape of γ-Al2O3 and its influence on propane dehydrogenation over single-atom Pt catalysts. Two energetically favorable structures, γ-no aluminum vacancy (NAV) and γ-aluminum vacancy (AV), are identified with energies lower than the conventional model by up to 34.44 meV·(f.u.)−1. These optimized structures expose abundant penta-coordinated Al3+ sites on the (100) surface, serving as preferred anchoring sites for Pt atoms. Simulated X-ray diffraction patterns indicate that γ-AV shows better qualitative agreement with experimental data. Surface phase diagrams further reveal that defect-rich surfaces are thermodynamically stabilized under realistic reaction conditions. Catalytic calculations demonstrate that γ-NAV and γ-AV significantly reduce propane dehydrogenation activation barriers through enhanced metal-support interactions associated with penta-coordinated Al3+ sites and defect-modulated local environments. These results suggest that γ-Al2O3 is better described as an ensemble of defect-rich surface configurations rather than a single crystal structure. These findings establish a direct relationship between atomic structure, defect chemistry, and catalytic performance in γ-Al2O3.

Photocatalytic C-N coupling offers a promising approach for the sustainable production of amino acids, but the uncontrolled coupling pathway of reaction intermediates limits yield and selectivity. This paper describes a Pd-B diatomic catalyst that can selectively catalyze the photosynthesis of glycine via C-N coupling reaction between waste poly(ethylene terephthalate)-derived ethylene glycol and nitrate, achieving a glycine yield of 2.9 mmol gcat-1 h-1 with a selectivity of 92%. Mechanistic investigations reveal that ethylene glycol is photo-oxidized to glycolaldehyde at the hole-rich B site, while nitrate is photo-reduced to NH4+/NH3 at the electron-rich Pd site. Subsequently, glycolaldehyde undergoes C-N coupling with NH4+/NH3, and further photo-oxidized to form glycine. The Pd-B diatomic site more effectively stabilizes the glycolaldehyde intermediate, resulting in a more favorable C-N coupling pathway than metal oxide and enhancing glycine selectivity. Thus, we show a catalytic system for selective glycine photosynthesis by precisely regulating the reaction pathways of key intermediates.

Photothermal CO2 methanation presents a promising strategy for mitigating the energy crisis and reducing CO2 emissions, however, the critical role of hydrogen migration dynamics in addressing reaction kinetics and thermodynamics has not been thoroughly investigated. Here, we demonstrate the design of a (NiO/Ru0)/TiO2 photothermal catalyst with optimized interfacial architecture and enhanced hydrogen mobility, which facilitates exceptionally selective conversion of CO2-to-CH4. Both experimental and theoretical analyses reveal that H2 dissociates efficiently on Ru0, subsequently undergoing spillover to O in NiO (ONiO). This process not only redistributes active sites but also influences the reaction kinetics, thereby fundamentally altering the energy landscape associated with CO2 methanation. Consequently, the (NiO/Ru0)/TiO2 catalyst achieves complete CO2 conversion and CH4 selectivity, with a CH4 production rate of 2552.49 μmol h-1 (85.08 mmol g-1 h-1) under an irradiation of 25.5 suns without external heat or pressure. This research underscores an innovative engineering approach that leverages hydrogen spillover to enhance photothermal catalytic efficiency and selectivity, thereby providing a robust framework for the advancement of sophisticated photothermal catalysts for selective CO2 hydrogenation.

Bifunctional catalysis is pivotal to industrial heterogeneous catalytic processes, yet its performance is limited by the kinetic entanglement among different elementary steps. In the conversion of light alkanes to aromatics, a promising non-naphtha route to produce benzene, toluene and xylene (BTX) that examples this challenging, this paper describes a process-separated cascade catalysis (PSCC) for efficient BTX synthesis, prioritizing kinetic decoupling over spatial intimacy of active sites in bifunctional systems. We employ a spatially decoupled metal-zeolite catalyst, achieving >95% propane conversion and 82.3% aromatic selectivity with near-exclusive BTX formation at 550 °C during continuous reaction-regeneration cycles. In situ spectroscopies and kinetics analysis reveal that PSCC decouples kinetics of alkane dehydrogenation to olefine intermediates (ethene, propene) in the first stage and synchronizes this process with oligomerization and aromatization reactions in the second stage. This synchronization affords the rate matching of two stage, thus minimizes cracking by-products and enhances BTX production substantially. Combined with high catalytic stability and technoeconomic assessment, this PSCC strategy represents a robust pathway in alkane (C2-C4)-to-BTX conversion and beyond bifunctional catalysis processes.

Propane dehydrogenation (PDH) requires platinum (Pt) sites that couple high intrinsic activity with propylene selectivity, yet most Pt-based strategies that enhance selectivity rely on electronically modified metallic Pt and can compromise intrinsic rates. This paper describes a discovery that atomically dispersed, cationic Ptδ+ sites can be anchored on zincosilicate *BEA (CIT-6) via ion exchange at framework-derived paired negative charge environments. Transient measurements, (in situ) spectroscopic studies, kinetic analysis, and density functional theory calculations collectively show that Ptδ+ exhibits higher dehydrogenation activity than metallic Pt0, consistent with enhanced C-H bond polarization and facilitated C-H cleavage on electron-deficient centers. As a result, a 0.01 wt. % Ptδ+/CIT-6 catalyst achieves PDH activity comparable to a commercial (mimic) PtSnK/Al2O3 catalyst while using ∼30-fold less Pt. The same design concept extends to zincosilicate CHA and MFI frameworks, establishing framework-anchored positively charged Ptδ+ species as an active motif for Pt-efficient PDH catalysis.

Heterogeneous catalysis underpins the majority of industrial chemical manufacturing and is central to the low-carbon transition encompassing CO2 valorization, light-alkane upgrading, and waste upcycling. Rational catalyst design for these processes demands mechanistic insight far beyond what conventional bulk-averaged, ex situ methods can deliver. This review systematically assesses recent advances in spatiotemporally resolved operando characterization of industrial catalysts. We argue that the principal bottlenecks now lie not in detection sensitivity per se, but in reactor-cell fidelity (ensuring spectroscopic environments faithfully replicate industrial conditions) and, as a more nascent but rapidly emerging front, in data-model integration (converting high-dimensional operando datasets into predictive, multi-scale design rules). Along the spatial axis, super-resolution fluorescence microscopy (Nanometer Accuracy by Stochastic Chemical Reactions (NASCA), Super-resolution Optical Fluctuation Imaging (SOFI)) resolves single-molecule catalytic events at ∼20 nm precision, while synchrotron X-ray nanotomography and environmental transmission electron microscopy map compositional, structural, and thermal heterogeneities in three dimensions from the nanometer to the millimeter scale. Along the temporal axis, transient kinetic methods, notably Steady-State Isotopic Transient Kinetic Analysis (SSITKA) and modulation excitation spectroscopy with phase-sensitive detection, discriminate genuine reactive intermediates from spectator species, and multimodal coupling correlates metal-site electronic structure with surface adsorbate dynamics within a single experiment. At the spatiotemporal frontier, purpose-built reactor platforms including capillary profile reactors, Spatially Coupled MS (SpaciMS), Micro-Electro-Mechanical Systems (MEMS) nanoreactors, and magnetic resonance spectroscopic imaging enable real-time tracking of reaction and deactivation fronts in realistic catalyst architectures. These capabilities are illustrated through three case studies: intermediate identification and deactivation at the metal–support interface in CO2 hydrogenation, two-stage coking mechanisms in propane dehydrogenation, and feed-dependent deactivation in waste plastic and biomass upcycling. Finally, we outline a roadmap encompassing label-free nanoscopy, ultrafast X-ray Free-Electron Laser (XFEL) probes, and digital-twin-guided optimization to overcome these bottlenecks and translate spatiotemporal insights into rational catalyst design.

Silicon-based metal-insulator-semiconductor (MIS) photoelectrodes provide a built-in field for photoelectrochemical water splitting but suffer from inefficient charge transport due to carrier recombination at defect sites within the space-charge region. The insulating layer fabricated by atomic layer deposition (ALD) is critical for defect passivation and requires carefully engineered deposition and annealing processes for optimal performance. This necessitates the quantitative analysis of defect density distribution. However, such analysis remains impeded by intrinsic limitations of conventional single-capacitance techniques and the influence of tunneling leakage currents. This paper describes an integrated multicapacitance methodology that combines drive-level capacitance profiling (DLCP) and capacitance-voltage (C-V) techniques to quantify both interface (Nit) and bulk defect charge density (NDLCP) within the space-charge region, using the space-charge capacitance refined by MIS-adapted multicomponent equivalent circuit modeling. This approach reveals that Al2O3 reduces the Nit at n-Si/ITO interface from approximately 2.9 × 1016 to 1.4 × 1016 cm-3, while simultaneously profiling the variation of NDLCP and depletion width. Furthermore, systematic DLCP/C-V analysis enables the design of a tailored passivation protocol by tuning ALD deposition (Tdep) and annealing temperatures to leverage the hydrogen-induced mechanism. Optimal passivation is achieved at a moderate Tdep (∼160 °C) followed by 350 °C annealing, which balances sufficient hydrogen content and suitable structural properties of the Al2O3 film without introducing additional bulk defects during annealing. Eventually, the optimized n-Si/SiOx/Al2O3/ITO/Ni photoanode exhibits an onset potential of 0.88 V vs RHE and an applied bias photon-to-current efficiency (ABPE) of 2.91%, with a long-term stability of 120 h.

Heterogeneous catalytic CO2 hydrogenation has emerged as a versatile route for converting captured CO2 and renewable H2 into fuels and chemicals, with relevance to carbon circularity, energy storage, and the progressive defossilisation of chemical manufacturing. This review describes CO2 hydrogenation as a complex network capable of delivering CO, methanol, methane, formates, dimethyl ether, and a broad range of C2+ products. We examine how catalyst composition and structure, including metal nuclearity, metal-oxide interfaces, oxygen vacancies, acid-base properties, and pore confinement, govern pathway competition and product selectivity, and we discuss the growing importance of tandem and multifunctional catalytic platforms. Particular attention is given to the dynamic evolution of active phases under reaction conditions, and to the role of in situ and operando characterisation, together with theoretical and kinetic analysis, in establishing meaningful structure-performance relationships. We further consider the emerging contribution of data-driven methods to catalyst screening, descriptor discovery, and optimisation. Beyond catalyst-level advances, this review addresses reactor and process constraints, including transport effects, scale-up, separation, feed variability, and system integration, and examines how life-cycle assessment, techno-economic analysis, and pilot-scale validation are needed to distinguish laboratory performance from deployable value. Taken together, this review provides an integrated framework for evaluating the scientific basis and practical prospects of CO2 hydrogenation in a net-zero context.

Heterogeneous electrocatalytic reactions driven by renewable electricity offer a route for chemical production. To advance these technologies towards applications, it is essential to maximize the use of each valuable electron, to drive valorization reactions at both the anode and cathode. Coupled electrocatalytic systems with well designed integrated anodic and cathodic reactions could simultaneously improve process efficiency and product value. This Review describes the technical principles and economic considerations for coupling electrocatalytic reactions. Technically, a well designed coupled system should reduce the reaction potential for elevated energy efficiency, with matched mass flow and electron consumption at both electrodes. Additional technical principles include streamlining downstream processing and improving operational safety. Economically, an integrated techno-economic assessment framework could comprehensively consider the financial, environmental and regulatory impacts. The coupling viability score, which combines economic, environmental and uncertainty information, could enable quantitative comparisons of coupled systems. Coupled electrochemical systems for green hydrogen production with alternative anodic reactions, carbon dioxide utilization for C1 products, and organic valorization through cascade and convergent architectures show favourable economic viability. Further development in electrocatalyst design, electrode construction and electrolyser optimization, supported by advanced characterization techniques, computational simulations and artificial intelligence, together with the full guidance of economic analysis, is needed for the implementation of coupled electrocatalytic systems. Coupling electrocatalytic reactions could enable more efficient and economically viable systems for chemical production. This Review discusses key technical and economic principles for the development of coupled electrocatalytic systems.

Single‐site pairs are promising in achieving high selectivity and activity in alkyne semihydrogenation, but its applicability is limited by the insufficient activity because pair sites cannot adsorb and activate alkyne. Here, we couple single‐site Pd with Jahn–Teller active Cu atoms of Cu‐doped Fe 2 O 3 to construct a highly active and stable single‐site Pd‐Cu pairs. The Jahn–Teller active Cu possesses elongated axial orbitals, and the strong electronic coupling between Pd and Cu further contributes to their unoccupied axial d orbitals, which helps Pd‐Cu pair to cooperatively activate C 2 H 2 molecule, unlike ordinary single‐site pairs where only H 2 is activated. As a result, this catalyst exhibits state‐of‐the‐art performance, with > 99.99% conversion and 95.5% selectivity as well as excellent stability with negligible performance decay after 300‐h test in purifying acetylene of ethylene stream. Both in situ spectra and theoretical results indicate two H addition steps occur on Pd and Cu sites in sequence. This work opens an avenue for constructing highly efficient single‐site pairs for selective hydrogenation and beyond.

Metal‐containing hybrid resists have attracted considerable attention for advanced lithography owing to their superior performance in resolution, sensitivity, and etch resistance.Beyond these benefits, vapor‐deposited dry hybrid resists offer distinct advantages in film‐component uniformity and process compatibility.However, such vapor‐deposited dry resists typically form highly cross‐linked covalent networks, which require aggressive development conditions for patterning and may not effectively establish a significant solubility switch upon exposure.This paper describes the design and fabrication of a molecular layer deposition (MLD)‐based dry resist featuring a restricted covalent network, enabled by the unique reactivity of ε‐caprolactone (CL). During deposition, nonring‐opening reactions and double reaction pathways of some ε‐caprolactone precursors systematically disrupt the long‐range network integrity, thereby significantly enhancing the solubility of the film in deionized water. E‐beam exposure tests confirmed that this resist is developable in deionized water, exhibiting a critical exposure dose of approximately 200 μC·cm−2, which is lower than many other MLD resists. Infrared spectroscopy (IR) and X‐ray photoelectron spectroscopy (XPS) analyses reveal that the exposure mechanism primarily involves the cleavage of CO, HfO, and HfN bonds, inducing the detachment of main chain ε‐caprolactone molecules from the film matrix.

The chemical looping steam reforming of methane (CL-SRM) holds immense potential for energy-efficient conversion of CH4 into syngas and high-purity hydrogen. However, its large-scale implementation remains limited by high operating temperatures and substantial energy requirements. This paper describes a non-thermal plasma-mediated CL-SRM process based on CH4/H2O redox cycles over lanthanum-based perovskites under mild conditions. The developed process achieves efficient CH4 activation at 600 °C, attaining 53.5% CH4 conversion and 0.57 mmol∙g−1 H2 with 92% purity over La0.5Ce0.5FeO3, while negligible conversion is observed under plasma-free conditions at the same furnace temperature. These performances surpass those observed under purely thermal conditions at 800 °C. Mechanistic insights reveal that plasma plays a crucial role in generating vibrationally excited CH4v species, thereby markedly lowering the reaction barrier for CH4 activation. The plasma-mediated CL-SRM process delivers energy through voltage-induced electron transfer, offering the potential for adiabatic reactor designs that minimize energy consumption compared with conventional combustion-based systems suffering from heat transfer limitations.

To realize industrially feasible CO2 conversion, it is particularly important to achieve efficient catalysis in large-area electrocatalytic CO2 reduction (CO2RR) electrolyzers. However, the flooding and salt precipitation within electrolyzers make this extremely challenging. Currently, hydrophobic Teflonated carbon papers (TCPs) are widely used in CO2RR electrolyzers. However, the use of TCP can lead to poor electrode conductivity, catalyst agglomeration, and detachment, thereby reducing the catalytic performance of the electrolyzers. This paper describes the design and construction of a three-dimensional hydrophobic catalytic structure by modifying hydrophilic raw carbon paper with tetrafluorooctyltriethoxysilane and spraying Ag catalyst. By analyzing the catalytic performance, surface ion concentration, and salt precipitation distribution of the electrode, the optimization effect of the three-dimensional hydrophobic catalytic structure on the three-phase interface is elucidated. The results show that the three-dimensional catalytic structure effectively increases the catalytic area, reduces the penetration of electrolyte into the electrode, and reduces salt precipitation. Meanwhile, the three-dimensional catalytic structure facilitates efficient charge transfer and regulates the H2O and CO2 concentrations around the catalysts. After operating at a current density of 200 mA/cm2 for 100 h in KOH solution, the Faraday efficiency of CO remains above 88

Polyolefins account for more than half of global plastic production. However, their short service life and limited recyclability have led to severe environmental pollution and substantial resource loss. Catalytic valorization has emerged as a promising strategy to convert polyolefin waste into high-value chemicals and fuels. In practice, progress toward deployable valorization technologies depends on coordinated innovation across the connected catalyst-process-reactor chain at different length scales, spanning molecular-scale active-site chemistry, process development and optimization, and reactor selection and design. This review describes recent advances in the catalytic valorization of polyolefins from an integrated, multiscale perspective, encompassing catalyst design, process engineering, and reactor development. We first discuss the design principles and reaction mechanisms of representative catalytic systems, including metal catalysts, solid acid catalysts, bifunctional catalysts, and ionic liquid catalysts, with an emphasis on how catalyst properties dictate reaction pathways and product selectivity. Building on these insights, process innovations, such as mixed catalysts, co-conversion with small molecules (CH4, CO2, C2H4, CO, and CH3OH), and external-field-assisted transformations (plasma, microwave, and Joule heating), are analyzed in terms of their roles in enhancing catalytic activity, selectivity, and stability. Furthermore, recent developments in batch, fixed-bed, and fluidized-bed reactors are reviewed, highlighting the influence of heat and mass transfer, continuous operation, and scalability on overall process performance. Finally, we conclude by outlining critical gaps that currently hinder translation from lab studies to real-world waste streams and by proposing opportunities to accelerate catalyst and process development.

Abstract Photocatalytic reaction efficiency is governed by the spin states of active center and reaction intermediates, as it allows selective formation of desired products through spin-dependent reaction pathways. As a representative process, photocatalytic overall water splitting remains limited by water oxidation reaction, where spin-dependent formation of triplet-state O2 is thermodynamically and kinetically unfavorable. This work describes an atom-specific spin modulation strategy by selectively substituting tetrahedral Co2+ with Ni2+ in spinel Co3O4 to form NiCo2O4, which reconstructs the local coordination environment and charge distribution of octahedral Co3+, constructing a high-spin configuration with increased eg occupancy. Under the constraint of external magnetic field, high-spin Co3+ atom generates aligned parallel ·OH radicals, favoring the formation of triplet-state O2 while suppressing singlet byproducts. Meanwhile, the enhanced eg occupancy weakens the adsorption of oxygenated intermediates, lowering the Gibbs free energy barrier of the rate-determining step and accelerating water oxidation. Hence, the NiCo2O4/BiVO4 photocatalyst achieves a water oxidation rate of 148.5 ± 3.7 μmol h−1, which is 5.6 times higher than the pristine BiVO4. Furthermore, it enables near-stoichiometric overall water splitting with a solar-to-hydrogen efficiency of up to 0.309 ± 0.003%. This work underscores the importance of atom-specific spin state regulation to promote spin-polarization-dependent photocatalytic water splitting.

Abstract The electrochemical CO2 reduction reaction (eCO2RR) on CuGa alloys exhibits nonmonotonic selectivity trends that remain mechanistically unexplained. Here, we employ density functional theory (DFT) to investigate three model surfaces (Cu(111), Cu9Ga4(110), CuGa2(110)) spanning the experimentally relevant Ga content range. Ga incorporation progressively strengthens surface oxygen affinity (from 0.47 eV to −0.13 eV) while hydrogen affinity evolves nonmonotonically: Cu9Ga4 binds H slightly more strongly than Cu(111) (−0.04 vs 0.07 eV), while CuGa2 shows the weakest H binding among the three surfaces (0.27 eV). This provides a thermodynamic framework for interpreting selectivity. The free energy landscape analysis identifies *CHO as the pivotal intermediate governing C1 vs C2 branching, with CuGa2 favoring methanol due to diminished *CHO stability despite favorable C–C coupling thermodynamics. For C2 products, the ethylene/ethanol bifurcation at *CH2CHO is controlled by competing C–O cleavage and hydrogenation pathways. Cu9Ga4 exhibits superior ethylene selectivity through a dual geometric mechanism: square-like Cu sites weaken the C–O bond in *CH2CHO (ICOHP: −12.29 vs −12.60 eV on Cu) while sterically suppressing *CH3CHO formation. These findings reveal that Ga regulates eCO2RR selectivity through content-dependent electronic effects and phase-specific geometric effects, offering mechanistic design considerations for CuGa intermetallic catalysts.