Lattice-Engineered Dual-Electron-Drive Electrode for Selective Ammonia Production From Nitrate.

Abstract

Ammonia (NH₃) is indispensable in agriculture and emerging energy systems, yet its conventional production remains energy- and carbon-intensive. Electrochemical nitrate reduction reaction (NO₃ ^-RR) represents a promising alternative for sustainable NH₃ synthesis but is hampered by slow kinetics and low selectivity under realistic, neutral conditions. Here, we employ the lattice engineering strategy to construct a cobalt-doped nanoscale zerovalent iron (Co-nFe⁰) electrode that integrates a dual-electron-drive mechanism with a self-triggered alkaline microenvironment to overcome these challenges. Cobalt doping modulated the surface Fe electronic structure to create electron-deficient Fe sites, which enhanced charge transfer, promoted water dissociation into active hydrogen species, and facilitated the hydrogenation of reaction intermediates. This design enabled an NH₃ Faradaic efficiency of 96% and near-quantitative selectivity across a wide nitrate concentration range (100-1000 mg L^-1 NO₃ ^--N), alongside sustained operational stability. An insitu NH₃ recovery system could provide stable operation over 360 h and deliver 13 g day^-1 NH₃ production with 100% NH₃ recovery. Rice pot experiments demonstrated that the recovered ammonium sulfate (99% purity) performed comparably to commercial fertilizers. This work provides an efficient electrocatalyst that couples electronic structure modulation and interfacial microenvironment regulation, thereby offering a sustainable technological route for nitrogen upcycling and green fertilizer production.