Research progress on alloy catalysts in the electrocatalytic reduction of nitrates for ammonia production

Electrocatalytic nitrate reduction to ammonia (eNO 3 RR) offers a sustainable route that simultaneously addresses nitrate pollution remediation and green ammonia synthesis; however, its intrinsically coupled multi-electron/multi-proton reaction pathway and the intense competition from the hydrogen evolution reaction (HER) severely hinder the concurrent enhancement of catalytic activity, selectivity, and stability. In recent years, alloy catalysts have exhibited pronounced advantages in eNO 3 RR due to their tunable electronic structures, cooperative multi-active-site architectures, and rich interfacial effects. This review systematically surveys recent advances in alloy catalysts for eNO 3 RR, encompassing non-precious-metal solid solutions and doped bimetallic systems, single-atom alloys (SAAs) and dual-atom catalysts (DACs), metal-metal and metal-oxide heterostructures, multiphase tandem and confined multimetallic architectures, as well as MOF-derived alloys and self-supported, engineered electrodes. Particular emphasis is placed on elucidating how compositional modulation, site engineering, interfacial synergy, and support stabilization collectively govern nitrate activation, stepwise hydrogenation, and the suppression of the HER. By offering a unified abstraction of diverse synergistic strategies, this review reveals that functional division among multiple active sites, together with reaction-pathway matching, is central to overcoming the activity-selectivity trade-off, and further distills alloy catalyst design principles toward high-current-density operation and practical implementation. • A comprehensive review of alloy catalysts for eNO 3 RR. • Mechanistic insights into alloy catalyzed eNO 3 RR and reaction pathway regulation. • Universal synergy from single-to multi-site alloy catalysts in eNO 3 RR.