New insights into mechanisms on electrochemical N2 reduction reaction driven by efficient zero-valence Cu nanoparticles

Electrochemical N2 reduction reaction (NRR) catalyzed by transition-metal-based electrocatalysts offers the sustainable strategy to directly convert N2 to NH3 at ambient conditions, but it is still extremely challenging for such catalysts to simultaneously obtain a high Faradaic efficiency (FE) and a large NH3 yield. Herein, we report the zero-valence Cu nanoparticles anchored on reduced graphene oxide (Cu NPs-rGO) as a highly effective NRR electrocatalyst for ambient N2-to-NH3 conversion in a neutral solution. When measured in 0.5 M LiClO4, the Cu NPs-rGO achieves a high Faradaic efficiency of 15.32% and a large NH3 yield of 24.58 μg h−1 mgcat.−1 at −0.4 V vs. reversible hydrogen electrode. In addition, such electrocatalyst possesses marvelous stability and selectivity as well. The density functional theory calculations are carried out to further investigate the catalytic mechanism.