Electrochemical Nitrogen Reduction for Green Ammonia: Mechanistic Insights and Advanced Materials Design

Electrochemical nitrogen reduction reaction (NRR) provides a promising pathway for sustainable ammonia synthesis under ambient conditions and direct integration with renewable electricity. However, practical implementation remains limited by sluggish N₂ activation, severe competition from the hydrogen evolution reaction (HER), low ammonia partial current densities, and insufficient long-term stability. Existing studies frequently address these challenges separately, focusing on catalyst classes or mechanistic pathways, leaving a gap between atomic-scale materials design and system-level requirements for scalable operation. In this Review, we present an integrative perspective on electrocatalytic NRR that links reaction kinetics, descriptor-guided materials design, and reactor-level considerations. Emerging catalyst architectures, including single-atom, dual-atom, vacancy-engineered, and metal-free systems, are critically evaluated, highlighting how cooperative active sites, electronic-structure modulation, and defect chemistry regulate N₂ adsorption, stabilization of key intermediates (particularly NNH), and suppression of HER. Mechanistic descriptors, scaling relations, and design principles are discussed alongside experimental performance trends to clarify thermodynamic and kinetic limits governing selectivity. Beyond catalyst discovery, we examine electrolyte and interphase engineering, gas-liquid-solid transport, pressure and flow management, durability, and ammonia handling. By connecting catalyst design, mechanistic descriptors, reactor constraints, and techno-economic targets, this Review outlines credible pathways toward scalable electrochemical ammonia production.