Tao Yao

The sluggish cathodic oxygen reduction reaction (ORR) and limited durability of Pt-based alloys remain major challenges for proton exchange membrane fuel cells (PEMFCs). Here, we report a Cu-assisted strategy to construct an ordered L12-PtCoCu intermetallic constructed through Cu incorporation and reductive annealing. The resulting ordered PtCoCu structure exhibits a relatively electron-rich Pt environment, contracted Pt–Co/Cu coordination, and compressive lattice strain. Consequently, L12-PtCoCu/C delivers a half-wave potential of 0.916 V and mass and specific activities of 0.71 A mgPt–1 and 0.98 mA cmPt–2, respectively, at 0.90 V. After 30,000 accelerated durability cycles, its half-wave potential decreases by only 3 mV. In membrane electrode assembly tests, L12-PtCoCu/C achieves peak power densities of 1.25 W cm–2 under H2–air and 2.50 W cm–2 under H2–O2 conditions. Operando synchrotron radiation infrared spectroscopy further reveals pronounced potential-dependent evolution of oxygenated intermediates and restructuring of interfacial water. These results highlight the correlation between atomic ordering, local Pt coordination, interfacial responses, and enhanced ORR performance.

Understanding how active sites dynamically respond to electrochemical polarization and control catalytic pathway selection remains a key challenge in multistep electrocatalysis. Here we show that electron‐withdrawing Mn doping endows Ca ₂ IrO ₄ with an enhanced transient response of Ir sites under acidic oxygen‐evolution conditions. Using time‐resolved energy‐dispersive x‐ray absorption spectroscopy, we directly capture Ir‐site evolution during a single voltammetric sweep, revealing a rapid potential‐induced increase in Ir oxidation state accompanied by strengthened Ir‐O covalency under anodic polarization. Operando characterizations and theoretical calculations demonstrate that this enhanced transient Ir‐site response facilitates lattice‐oxygen activation, thereby increasing the contribution of the lattice oxygen mechanism under working conditions. Consequently, Mn‐doped Ca ₂ IrO ₄ delivers 1 A cm ⁻² at 1.675 V in a proton‐exchange‐membrane water electrolyzer and maintains stable operation for over 500 h. These findings identify the transient Ir‐site response as an important factor regulating lattice‐oxygen participation in Ca ₂ IrO ₄ ‐based catalysts, providing a basis for designing Ir‐based oxides with tunable lattice‐oxygen chemistry.

Understanding how active sites dynamically respond to electrochemical polarization and control catalytic pathway selection remains a key challenge in multistep electrocatalysis. Here we show that electron‐withdrawing Mn doping endows Ca ₂ IrO ₄ with an enhanced transient response of Ir sites under acidic oxygen‐evolution conditions. Using time‐resolved energy‐dispersive x‐ray absorption spectroscopy, we directly capture Ir‐site evolution during a single voltammetric sweep, revealing a rapid potential‐induced increase in Ir oxidation state accompanied by strengthened Ir‐O covalency under anodic polarization. Operando characterizations and theoretical calculations demonstrate that this enhanced transient Ir‐site response facilitates lattice‐oxygen activation, thereby increasing the contribution of the lattice oxygen mechanism under working conditions. Consequently, Mn‐doped Ca ₂ IrO ₄ delivers 1 A cm ⁻² at 1.675 V in a proton‐exchange‐membrane water electrolyzer and maintains stable operation for over 500 h. These findings identify the transient Ir‐site response as an important factor regulating lattice‐oxygen participation in Ca ₂ IrO ₄ ‐based catalysts, providing a basis for designing Ir‐based oxides with tunable lattice‐oxygen chemistry.

Electrochemical CO ₂ ‐to‐CH ₄ conversion on Cu–N–C single‐atom catalysts is fundamentally limited by *H/*CO spatial mismatch from numerous metal‐free CN matrix, where the long‐range hydrogen transfer easily causes *H coupling or *CO dimerization, ultimately impeding *CHO formation. Herein, we design a two‐dimensional metal–organic polymer catalyst featuring spatially adjacent Cu and 1H‐benzotriazole to form Cu‐π units, which achieves a Faradaic efficiency of 61% for CH ₄ at 800 mA·cm ⁻² . Using Infrared free‐electron laser (IRFEL) nanospectroscopy, we identify the key Cu‐π coordination environment and low‐frequency bonding modes, unavailable by conventional IR techniques. Complementary in‐situ synchrotron radiation IR, electrochemical experiments and theoretical calculations reveal that π sites adsorb hydrated cations, enabling localized hydrogen supply to adjacent *CO on Cu sites and suppressing long‐range hydrogen transfer‐induced side reactions. This inorganic–organic synergy paves a new pathway to spatially match *H and *CO, advancing efficient CO ₂ ‐to‐hydrocarbons conversion.

Electrochemical CO ₂ ‐to‐CH ₄ conversion on Cu–N–C single‐atom catalysts is fundamentally limited by *H/*CO spatial mismatch from numerous metal‐free CN matrix, where the long‐range hydrogen transfer easily causes *H coupling or *CO dimerization, ultimately impeding *CHO formation. Herein, we design a two‐dimensional metal–organic polymer catalyst featuring spatially adjacent Cu and 1H‐benzotriazole to form Cu‐π units, which achieves a Faradaic efficiency of 61% for CH ₄ at 800 mA·cm ⁻² . Using Infrared free‐electron laser (IRFEL) nanospectroscopy, we identify the key Cu‐π coordination environment and low‐frequency bonding modes, unavailable by conventional IR techniques. Complementary in‐situ synchrotron radiation IR, electrochemical experiments and theoretical calculations reveal that π sites adsorb hydrated cations, enabling localized hydrogen supply to adjacent *CO on Cu sites and suppressing long‐range hydrogen transfer‐induced side reactions. This inorganic–organic synergy paves a new pathway to spatially match *H and *CO, advancing efficient CO ₂ ‐to‐hydrocarbons conversion.

Tandem carbon dioxide reduction reaction (CO ₂ RR) to multicarbon products (CO ₂ -CO-C ₂₊ ) such as ethylene represents a pivotal strategy for carbon valorization. However, conventional alkaline or neutral tandem systems limit the carbon dioxide utilization and stability due to severe (bi)carbonate formation. Here, we design a durable acidic-alkaline tandem system to efficiently synthesize C ₂₊ products, especially ethylene. In the acidic CO ₂ RR step, a catalyst with precisely controlled metal site distance was used to regulate *COOH adsorption. Typically, a 99.7 ± 0.4% carbon monoxide Faradaic efficiency (FE) at 1.4 amperes per square centimeter can be achieved using a catalyst with 0.5-nanometer nickel sites, surpassing the previously reported metal catalysts. When this catalyst was integrated into the acidic-alkaline tandem system and coupled with the alkaline carbon monoxide electroreduction, the ethylene and C ₂₊ FE reached 75.3 ± 1.2 and 92.5 ± 1.3% at 10 amperes, respectively, and remained stable for 400 hours. Our work provides solutions for the durable conversion of carbon dioxide to C ₂₊ products from catalyst and electrolyzer design.

Cu ^δ+ species are recognized as optimal active sites for the electrocatalytic CO ₂ reduction reaction. While metal‐support interactions (MSIs) modulate the local microenvironment of Cu ^δ+ , the intrinsic contribution of support crystallographic facets to these interactions remains obscured by interfering oxygen vacancies. In this work, we present a definitive study decoupling the facet effect from vacancy‐related variables by utilizing CeO ₂ supports with comparable oxygen vacancy concentrations. Our findings reveal that Cu single atoms supported on various CeO ₂ facets follow a pronounced facet‐dependent stability order of Cu/CeO ₂ ‐(110) > Cu/CeO ₂ ‐(100) > Cu/CeO ₂ ‐(111), yet exhibit facet‐independent methane Faraday efficiency (∼80% at −200 mA/cm ² ). Mechanistic studies unravel this dichotomy, revealing that identical Cu coordination environments drive the uniform initial activity, whereas distinct surface electronic structures dictate long‐term stability by modulating facet‐dependent MSIs. Specifically, the (110) facet exhibits the strongest MSI, acting as a robust “electron buffer” that securely anchors high‐valent Cu ^δ+ species and effectively retards their irreversible reductive agglomeration into clusters. By establishing an unambiguous structure–performance relationship under single‐variable conditions, this study provides a rational geometric descriptor for designing long‐lasting CO ₂ conversion catalysts.

Cu ^δ+ species are recognized as optimal active sites for the electrocatalytic CO ₂ reduction reaction. While metal‐support interactions (MSIs) modulate the local microenvironment of Cu ^δ+ , the intrinsic contribution of support crystallographic facets to these interactions remains obscured by interfering oxygen vacancies. In this work, we present a definitive study decoupling the facet effect from vacancy‐related variables by utilizing CeO ₂ supports with comparable oxygen vacancy concentrations. Our findings reveal that Cu single atoms supported on various CeO ₂ facets follow a pronounced facet‐dependent stability order of Cu/CeO ₂ ‐(110) > Cu/CeO ₂ ‐(100) > Cu/CeO ₂ ‐(111), yet exhibit facet‐independent methane Faraday efficiency (∼80% at −200 mA/cm ² ). Mechanistic studies unravel this dichotomy, revealing that identical Cu coordination environments drive the uniform initial activity, whereas distinct surface electronic structures dictate long‐term stability by modulating facet‐dependent MSIs. Specifically, the (110) facet exhibits the strongest MSI, acting as a robust “electron buffer” that securely anchors high‐valent Cu ^δ+ species and effectively retards their irreversible reductive agglomeration into clusters. By establishing an unambiguous structure–performance relationship under single‐variable conditions, this study provides a rational geometric descriptor for designing long‐lasting CO ₂ conversion catalysts.