Understanding the Activity Trends in Electrocatalytic Nitrate Reduction to Ammonia on Cu Catalysts
Haibo Yin, Dong Feng, Yunlong Wang, Haiwei Su, Xiansheng Li, Yue Peng, Haohong Duan, Junhua Li
Abstract
Cu-based catalysts possess great potential in the electrocatalytic nitrate (NO 3 – ) reduction reaction for ammonia (NH 3 ) synthesis. However, the low atomic economy limits their further application. Here we report a Cu single-atom (SA) incorporated in nitrogen-doped carbon (Cu SA/NC) with high atomic economy, which exhibits superior NH 3 Faradaic efficiency (FE) of 100% along with an impressive NH 3 yield rate of 7480 μg h –1 mg cat. –1 . As counterparts, Cu s+n /NC, with mixed SA and nanoparticles (NPs), shows decreasing NH 3 FE with decreasing SA content, but the production of N 2 and N 2 O increases gradually, which reaches the maximum on pure Cu NPs. In situ characterizations and theoretical calculations reveal that a higher NH 3 FE of Cu SA/NC is ascribed to a lower free energy of the rate-limiting step (HNO* → N*) and effective inhibition for the N-N coupled process. This work provides the intuitive activity trends of Cu-based catalysts, opening an avenue for subsequent catalysts design.