Regulation of Relay Catalytic Mechanism for Efficient Methanol Oxidation Reaction.

The methanol oxidation reaction serves as a representative model for multistep catalytic processes involving diverse intermediates. Catalyst design strategies that spatially arrange discrete active sites, analogous to relay runners, facilitate the sequential activation of reaction steps, thereby enhancing overall catalytic efficiency compared to single-site catalysts. This approach effectively decouples complex reaction networks into a sequence of coordinated elementary steps, thereby enhancing the production efficiency of the target products. Here, we propose a relay catalysis paradigm through electrochemical in situ construction of NiOOH-MoC@C heterojunction featuring with dual Lewis acid sites. By precisely controlling interfacial methanol/OH concentration gradients, nearly 100% Faradaic efficiency for formate production is achieved during methanol electrooxidation. Multiscale characterizations combined with density functional theory computations reveal that the engineered interface regulates *CHO intermediate migration from NiOOH to MoC domains, thereby effectively shifting the rate-determining step from *CHO-OH coupling to O─H bond cleavage. This spatial decoupling strategy reduces the thermodynamic barrier by 1.18 eV. This study elucidates a design strategy that tailors the spatial distribution of electrochemical interface species to guide catalytic pathway optimization. Furthermore, it highlights the essential role of heterojunction-mediated relay catalysis in enhancing electrocatalytic activity for the oxidation of organic small molecules.