Modulated metal-support interactions for efficient nitrate electroreduction at positive potentials

Electrochemical nitrate upgrading presents a sustainable route for repairing unbalanced nitrogen cycle. However, the low energy efficiency caused by high overpotential impedes the industrialization progress. Herein, Ru clusters supported on metal hydroxide are constructed by a universal self-corrosion strategy, and the metal-support interaction is modulated to simultaneously optimize NO3− adsorption and water dissociation for achieving high energy efficiency at positive potentials. The Co(OH)2-supported Ru with moderate metal-support interaction exhibits a high energy efficiency of 49.5% and a high NH3 Faradaic efficiency of ~100% at positive potentials. Furthermore, a long-term stability over 1200 h is achieved at an industrial-scale current density of 200 mA cm−2. Moreover, the assembled rechargeable hybrid battery system shows a great potential in waste upcycling and energy conversion. This work underscores the significance of metal-support interaction for promoting nitrate electroreduction at positive potentials. Electrochemical nitrate upgrading is restricted by high overpotential with low energy efficiency. Here, the authors report a metal-support modulation strategy to simultaneously optimize nitrate adsorption and water dissociation for achieving high energy efficiency at positive potentials.