Theoretical Insights into the Mechanism of Selective Nitrate‐to‐Ammonia Electroreduction on Single‐Atom Catalysts

Abstract

Selective nitrate‐to‐ammonia electrochemical conversion is an efficient pathway to solve the pollution of nitrate and an attractive strategy for low‐temperature ammonia synthesis. However, current studies for nitrate electroreduction (NO 3 RR) mainly focus on metal‐based catalysts, which remains challenging because of the poor understanding of the catalytic mechanism. Herein, taking single transition metal atom supported on graphitic carbon nitrides (g‐CN) as an example, the NO 3 RR feasibility of single‐atom catalysts (SACs) is first demonstrated by using density functional theory calculations. The results reveal that highly efficient NO 3 RR toward NH 3 can be achieved on Ti/g‐CN and Zr/g‐CN with low limiting potentials of −0.39 and −0.41 V, respectively. Furthermore, the considerable energy barriers are observed during the formation of byproducts NO 2, NO, N 2 O, and N 2 on Ti/g‐CN and Zr/g‐CN, guaranteeing their high selectivity. This work provides a new route for the application of SACs and paves the way to the development of NO 3 RR.