Electrocatalytic nitrogen reduction to ammonia by atomically precise Cu6 nanoclusters supported on graphene oxide

Abstract

The electrocatalytic nitrogen reduction reaction (NRR) enables the production of ammonia by the use of renewable energy, providing a direct method for nitrogen fixation. Nevertheless, the NRR process under ambient conditions is often impeded by inertness of N₂ and the occurrence of hydrogen evolution as a byproduct in aqueous electrolytes, resulting in a diminished reaction rate and reduced efficiency. In this study, we synthesized Cu₆(SMPP)₆ nanoclusters (Cu₆ NCs for short) and immobilized them on graphene oxide (GO) to investigate their electrocatalytic nitrogen reduction reaction (ENRR) using an H-cell setup. The GO-supported Cu₆ NCs exhibit enhanced catalysis with a high NH₃ yield rate of 4.8 μg h⁻¹ cm⁻² and a high faradaic efficiency up to 30.39% at −1.1 V. Quantum chemistry calculations reveal that the Cu₆S₆ cluster on GO support facilitates the N₂ adsorption and NN bond activation with a surmountable energy barrier for the potential-determining step (N₂* → NNH*).