Controlled Hydrogen Delivery by Single-Atom Ru Accelerates Electrocatalytic Ammonia Synthesis.

Electrocatalytic nitric oxide reduction to ammonia (NORR) offers a dual opportunity for NO remediation and decentralized NH3 production, yet its efficiency is often limited by competing pathways and unclear structure-function relationships. Here we introduce a reactant-shunting strategy that installs a guiding electrocatalytic step via isolated Ru atoms to supply surface-bound *H species and enforce a Langmuir-Hinshelwood (LH) hydrogenation pathway. Using Ru1/Co3O4 as a model catalyst, we show that single Ru sites promote water adsorption and dissociation, forming stable Ru-H intermediates that thermodynamically and kinetically accelerate the coupling-hydrogenation steps in NORR. The optimized catalyst delivers an NH3 yield of 533.49 µmol cm-2 h-1 with a 97.19% faradaic efficiency, surpassing state-of-the-art systems. The reactant-shunting principle further generalizes across multiple oxide hosts, enhancing NH3 productivity by up to threefold. These findings establish pathway steering through controlled hydrogen delivery as a powerful strategy for high-efficiency electrocatalytic ammonia synthesis.