Enhancing ammonia electrosynthesis from nitrate on Ru-RuO2 electrodeposited film

Ruthenium-based electrocatalysts remain relatively underexplored for performance optimization in the nitrate electroreduction reaction (NO3RR). Herein, a highly roughened Ru-RuO2 composite surface is synthesized via an electrodeposition route under mild and cost-effective conditions and is evaluated as an electrocatalyst for NO3RR in alkaline media. Scanning electron microscopy reveals a nanoparticulate rough morphology, while X-ray photoelectron spectroscopy confirms the coexistence of metallic Ru0 and Ru4+ species at the surface. Under optimized conditions, the as-prepared Ru-RuO2 electrode exhibits a maximum Faradaic efficiency for ammonia production of 71% and an ammonia yield rate of 39.2 µmol h− 1 cm− 2 at 0.0 V vs. RHE. Upon prolonged NO3RR operation, the catalytic surface evolves toward a stable Ru(0)/Ru(IV) configuration, sustaining continuous NH3 formation with a Faradaic efficiency of 40% and a yield rate of 14.3 µmol h− 1 cm− 2. The persistence of activity is attributed to the dynamic stabilization of interfacial Ru(0)/Ru(IV) sites formed during electrolysis. These results establish electrodeposited Ru-RuO2 composites as a robust and efficient platform for durable and selective electrochemical nitrate to ammonia conversion under alkaline conditions.