Enhancing electrocatalytic N2 reduction to NH3 by introducing Ni heteroatoms into NiCuOx electrocatalyst

Abstract

Modulating the local electronic structure in 3d transition metal oxides is appealing in the N₂ reduction reaction (NRR), yet remains challenging. Herein, Ni dopants with higher electronegativity are introduced to tune the electronic density of Cu in flower-like NiCuO_x through low-temperature calcination of the readily formed NiCu(OH)_x precursor. The as-obtained catalyst delivers a remarkable NH₃ production of 11.78 μg h⁻¹ mg_cat.^–1 with a high faradaic efficiency of 19.28% at a low voltage of −0.2 V, superior to most NRR electrocatalysts at similar voltages. XPS, in situ Raman, and DFT calculation reveal that the Ni dopant enhances the local electronic density surrounding Cu sites, which is favorable for reducing the energy barrier of the rate-determining (*N₂ to *NNH) step of the NRR as well as depressing the competing hydrogen evolution reaction. This work provides new insight into the effect of hetero-metal-atom doping on the NRR process and is instructive for the rational design of high-performance electrocatalysts.