Defect‐Driven Multimetal Synergy Enables Electrocatalytic Amine Valorization and Hydrogen Co‐Generation

ABSTRACT Sustainable nitrile synthesis remains a formidable challenge due to the high energy demands and environmental burden of conventional routes. Here, we present a defect‐engineered high‐entropy sulfide catalyst (FeCoNiMnWS ₂ /NF) that drives the electrooxidation of benzylamine to benzonitrile with 99% Faradaic efficiency and complete conversion. Operando studies reveal that atomic vacancies induce dynamic surface reconstruction, generating a heterogeneous catalytic interface composed of WS ₂ domains, Fe(Co/Ni)OOH, and W–O species, which facilitate N–H and C–H dehydrogenation. Machine‐learning‐assisted first‐principles calculations combined with microkinetic modeling show that WS ₂ edge sites dominate the catalytic activity, while adjacent oxyhydroxide and oxide species modulate the electronic structure through interfacial interactions. When integrated into a hybrid acid/alkali flow electrolyzer, the system achieves 10 mA cm ⁻² at 0.55 V, simultaneously yielding benzonitrile and high‐purity hydrogen with nearly quantitative efficiency. This work introduces a high‐entropy catalyst platform that couples amine valorization with energy co‐generation, charting a sustainable path toward electrified fine chemical synthesis.