Co 3 O 4 nanoparticles embedded in porous carbon nanofibers enable efficient nitrate reduction to ammonia.

The nitrate reduction reaction is emerging as having tremendous potential to mitigate nitrate pollution and simultaneously produce valuable ammonia. Here, we propose Co 3 O 4 nanoparticles embedded in porous carbon nanofibers (Co 3 O 4 @CNF) as a high-efficiency catalyst to convert nitrate to ammonia, and it achieves a high faradaic efficiency of 92.7% and an extremely large NH 3 yield of 23.4 mg h -1 mg -1 cat , and also presents excellent electrochemical stability. Theoretical calculations reveal that the potential determining step (PDS) reaches as low as 0.28 eV. This work is expected to open a new avenue to rationally design robust noble-metal-free catalysts for the electrochemical synthesis of ammonia.