Ambient ammonia production via electrocatalytic nitrate reduction catalyzed by a flower-like CuCo2O4 electrocatalyst

The electrochemical nitrate reduction reaction (NtRR) under ambient conditions is regarded as a potential approach to achieve NH3 production, which currently heavily relies on the Haber-Bosch process at the cost of a huge amount of energy and the massive production of CO2. Herein, a flower-like CuCo2O4 spinel was synthesized via a two-step urea-assisted hydrothermal treatment and calcination process. When used as the electrocatalyst for the NtRR, the as-synthesized CuCo2O4 spinel exhibits a high electrocatalytic activity, affording a high NH3 yield rate of 48.8 mu g h(-1) cm(-2) at -0.85 V (vs. RHE) and a high faradaic efficiency (FE) of 34.2% at -0.45 V (vs. RHE). The N-15 isotopic labelling experiments confirm that the yielded NH3 is, indeed, from the CuCo2O4 spinel catalyzed NtRR process. Our theoretical calculations results reveal that the NO3- can be adsorbed on the CuCo2O4 to form the *NOH intermediate, leading to a good selectivity and FE.