Dual metal synergy promotes electrocatalytic nitrate-to-ammonia conversion in neutral electrolyte

Electrocatalytic nitrate-to-ammonia reduction represents a feasible pathway for sustainable energy and environmental remediation. Despite significant advances in nitrate reduction reaction (NO₃RR), achieving satisfactory ammonia yield rates and Faraday efficiency (FE) in neutral environments remains challenging. Inspired by the enzymatic processes in nature, we have designed a tandem catalyst comprising bead-chain-structured CoC nanofibers decorated with Ag nanoparticles (Co-CNFs@Ag) for NO₃RR in neutral conditions. The dual metal synergy of Ag and Co enables efficient NO₃RR, breaks linear scaling relationship in the reaction pathway, and enhances energy utilization. Notably, under neutral electrolytic conditions with a low nitrate concentration (0.5 M K₂SO₄ + 0.05 M KNO₃), this catalyst achieves an ammonia yield rate of 4.50 ± 0.04 mg h^-1 cm^-2 at -0.89 V (vs. RHE). The performance exceeds most reported counterparts under comparable conditions. This study delivers not merely a high-performance catalyst toward NO₃RR under mild conditions, but further advances the conceptual framework for constructing efficient tandem systems for multi-step electrocatalytic reactions.