Co4N/Co2C@rGO with Abundant Co–C and N–C Bonds as Highly Efficient Electrocatalyst for N2 Reduction

Abstract

Ammonia is among the available sustainable fuels for humans in the future. Electrochemical nitrogen fixation, which is a promising ammonia synthesis method, can achieve artificial N2 fixation at room temperature and pressure. We report that 5% Co4N/Co2C@rGO is a high-efficiency nitrogen reduction reaction electrocatalyst for ammonia synthesis under ambient conditions. The catalyst obtains high NH3 yield (24.12 μg h–1 mgcat–1) and Faradaic efficiency (24.97%) at −0.1 V (vs RHE) in 0.1 M HCl. The addition of graphene reduces CoN to Co2C and Co4N. A high ratio of Co–C bonds improves NRR performance. The excellent performance of the catalyst is attributed to the high proportion of pyridine N and pyrrole N. Data analysis results show that the NRR on the surface of Co4N adopts a favorable Mars–van Krevelen reaction mechanism. Moreover, the Co2C(101) crystal plane is more conducive to NRR.