Boosting electrocatalytic nitrate reduction reaction for ammonia synthesis by plasma-induced oxygen vacancies over MnCuOx

Ammonia production from electrocatalytic nitrate reduction reaction (NO3RR) is a significant research field to potentially substitute the Haber-Bosch process. However, low ammonia selectivity due to competitive hydrogen evolution reaction is an issue for the NO3RR. In this study, a series of manganese copper oxide (MnCuOx) catalysts with different concentrations of oxygen vacancies have been prepared via Ar or O2 plasma treatments. MnCuOx-H with high concentration of oxygen vacancies showed a high NH3 yield rate of 9.4 mg cm-2h−1 and Faradaic efficiency of 86.4 %. The high performance of MnCuOx-H for the NO3RR can be resulted from the feature that the more oxygen vacancies formed from the plasma treatment could facilitate adsorption and weakening NO bonds of NO3. This strategy suggests a novel guidance to the catalyst design for NO3RR, which requires great improvements in terms of NH3 selectivity and production rate.