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

Abstract

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.