Interfacial Electron–Proton Dual Modulation of Fe Single‐Atom Catalyst by α ‐MoC for O 2 Activation and Lignin Depolymerization

ABSTRACT Efficient O 2 activation under mild conditions is central to oxidative biomass valorization, yet single‐atom catalysts often suffer from sluggish proton‐coupled oxygen intermediate conversion, particularly because of overly strong *OH adsorption. Inspired by the cooperative electron and proton management in cytochrome c oxidase, we report an α ‐MoC/Fe–N 4 catalyst in which α ‐MoC nanoparticles are interfaced with Fe–N 4 single‐atom sites on a nitrogen‐doped carbon scaffold. The α ‐MoC component plays a dual role: it withdraws electron density from Fe sites to weaken oxygen‐intermediate adsorption and promotes water dissociation to provide local protons for *OH‐to‐H 2 O conversion. As a result, α ‐MoC/Fe–N 4 exhibits a 2.8‐fold higher V max for O 2 activation than Fe–N 4 and proceeds through a nearly four‐electron oxygen reduction pathway with negligible reactive oxygen species (ROS) generation. This interfacial strategy is generalizable to various M–N–C single‐atom catalysts, including Mn, Co, Ni, Cu, Sn, Ir, and Pt. Enabled by efficient O 2 activation, α ‐MoC/Fe–N 4 depolymerizes native birch lignin under mild alkaline conditions, substantially decreasing its molecular weight and cleaving β –O–4, β – β , and β –5 linkages. This work establishes an electron‐proton dual‐modulation strategy for constructing high‐performance single‐atom catalysts for biomass conversion.