Abstract

Electrocatalytic nitrate reduction reaction (NO3RR) is a promising strategy to transform nitrate into harmless products and even valued-added products such as ammonia using renewable electricity. However, the poor understanding of the catalytic mechanism on metal-based catalysts hinders the development of high-performance NO3RR catalysts. Herein, by constructing multiple single transition metal atoms supported on oxygen vacancy MXene (Ov-MXene), the NO3RR mechanism of single-atom catalysts (SACs) is systematically explored by using density functional theory (DFT) calculations. The results show that highly efficient NO3RR toward NH3 can be achieved on Ag/Ov-MXene (for precious metal) and Cu/Ov-MXene (for non-precious metal) with low limiting potentials of −0.24 and −0.34 V as well as suppressing competitive hydrogen evolution reaction (HER). Furthermore, the high energy barriers are observed during the formation of byproducts NO2, NO, N2O, and N2 on Ag/Ov-Mxene and Cu/Ov-Mxene, guaranteeing their high selectivity of ammonia. This work provides new strategies for driving NH3 production by MXene-based SACs electrocatalysts under ambient conditions and developing NO3RR electrocatalysts.