Structural evolution-induced strong-coupling in CuRu-Cu2O nanocomposite enables low-overpotential electrocatalytic ammonia synthesis

Ammonia (NH 3 ) synthesis via nitrate reduction offers a sustainable energy conversion and mitigates aquatic NO 3 − pollution, yet most catalysts require high overpotentials for appreciable NH 3 yields. Here, we report a sulfur-leaching strategy to transform Cu 1.8 S/Ru heterostructures into a small CuRu-Cu 2 O nanocomposite with abundant heterointerfaces, enabling strong electronic coupling between CuRu and Cu 2 O particles, synergistically enhancing NO 3 – adsorption and reaction kinetics. The optimized catalyst achieves 95.4% NH 3 Faradaic efficiency at a low potential of 0.0 V versus reversible hydrogen electrode, stable over 30 cycles. Operando spectroscopy and density functional theory calculations reveal the incorporation of Ru facilitates active hydrogen generation, alleviating the energy barrier for hydrogenation steps at heterointerfaces. The catalyst demonstrates high stability in a membrane electrode assembly at 450 mA cm –2 over 200 h and enables a Zinc-NO 3 – battery operation exceeding 50 h, offering a design model for durable, active nanocomposites in sustainable NH 3 synthesis.