Xu, Xiaofeng; Wang, Ziyu; Zhang, Zhongyan; Guo, Pengfei; Shen, Di; Wei, Tianyi; Shi, Meiqin; Mei, Bingbao; Wu, Dongshuang; Sun, Fanfei

JOURNAL OF MATERIALS CHEMISTRY A

2025, 29,

Xu, Xiaofeng; Wang, Ziyu; Zhang, Zhongyan; Guo, Pengfei; Shen, Di; Wei, Tianyi; Shi, Meiqin; Mei, Bingbao; Wu, Dongshuang; Sun, Fanfei

The electrochemical nitrate (NO3-) reduction reaction (NO3RR) is hindered by nitrite (NO2-) accumulation and the competing hydrogen evolution reaction, limiting the faradaic efficiency (FE) and selectivity of ammonia (NH3) production. Herein, we report a cobalt-copper catalyst supported on biomass carbon (CoCu@BC) that achieves a high NH3 FE of 97.15% with an NH3 yield of 367.33 mu mol h-1 mgcat-1, while maintaining an NO2- FE of only 0.26% and NO2- concentrations below 10 mu g mL-1. In situ Fourier transform infrared spectroscopy confirms the presence of *NH2 and the absence of NO2- on the catalyst surface, indicating enhanced hydrogenation toward NH3 formation. In situ X-ray absorption fine structure analysis further demonstrates the structural stability of CoCu@BC during the reaction, supporting its sustained performance over 120 hours. Density functional theory calculations reveal that the heterogeneous Co-Cu interface optimizes the reaction energy barrier for *NO3 to *NO2 conversion, facilitating rapid reaction kinetics and enabling highly efficient and selective NH3 synthesis.