p-d orbital hybridization induced by CuGa2 promotes selective N2 electroreduction

Abstract

In the quest to align with industrial benchmarks, a noteworthy gap remains in the field of electrochemical nitrogen fixation, particularly in achieving high Faradaic efficiency (FE) and yield. The electrocatalytic nitrogen fixation process faces considerable hurdles due to the difficulty in cleaving the highly stable N≡N triple bond. Additionally, the electrochemical pathway for nitrogen fixation is often compromised by the concurrent hydrogen evolution reaction (HER), which competes aggressively for electrons and active sites on the catalyst surface, thereby reducing the FE of nitrogen reduction reaction (NRR). To surmount these challenges, this study introduces an innovative bimetallic catalyst, CuGa₂, synthesized through p-d orbital hybridization to selectively facilitate N₂ electroreduction. This catalyst has demonstrated a remarkable NH₃ yield of 9.82 μg h⁻¹ cm⁻² and an associated FE of 38.25%. Our findings elucidate that the distinctive p-d hybridization interaction between Ga and Cu enhances NH₃ selectivity by reducing the reaction energy barrier for hydrogenation and suppressing hydrogen evolution. This insight highlights the significance of p-d orbital hybridization in optimizing the electrocatalytic performance of CuGa₂ for nitrogen fixation.