Monodisperse Cu Cluster-Loaded Defective ZrO₂ Nanofibers for Ambient N₂ Fixation to NH₃

Electrocatalytic nitrogen reduction to ammonia has attracted increasing attention as it is more energy-saving and eco-friendly. For this endeavor, the development of high-efficiency electrocatalysts with excellent selectivity and stability is indispensable to break up the stable covalent triple bond in nitrogen. In this study, we report monodisperse Cu clusters loaded on defective ZrO₂ nanofibers for nitrogen reduction under mild conditions. Such an electrocatalyst achieves an NH₃ yield rate of 12.13 μg h^-1 mg_cat.^-1 and an optimal Faradaic efficiency of 13.4% at -0.6 V versus the reversible hydrogen electrode in 0.1 M Na₂SO₄. Density functional theory calculations reveal that the N₂ molecule was reduced to NH₃ at the Cu active site with an ideal overpotential. Meanwhile, the interaction between bonding and antibonding of the Cu-N bond promotes activation of N₂ and maintains a low desorption barrier.