Ruthenium-induced hydrolysis effect on Fe₂O₃ nanoarrays for high-performance electrochemical nitrate reduction to ammonia

Electrochemical nitrate reduction (NO₃^-RR) to ammonia (NH₃) has become an attractive pathway for sewage remediation and ammonia synthesis. However, the NO₃^- electroreduction reaction remains hindered by the sluggish multi-proton involved steps without sufficient proton supply. Herein, we designed Ru nanoparticles (NPs) loaded onto ferric oxide nanoarrays (Ru-Fe₂O₃) catalysts with hydrolysis effect for high-efficient NH₃ production. Ru-Fe₂O₃ exhibits an impressive ammonia yield and faraday efficiency (209–329 μmol cm⁻² h⁻¹ and 45.2–72.8%, respectively). Ru-induced hydrolysis promotes the hydrogenation of the reaction intermediates in the process (H₂O+e⁻→H*+OH⁻) by accelerating the generation of localized protons at the reactive sites. More importantly, this effect can further accelerate the H*-mediated indirect reduction pathway and the electron-mediated direct reduction pathway. These findings underscore the importance of relating NO₃^-RR performance with nanometallic particles-supported electrodes to advance catalyst design and operation.