Electrocatalytic reduction of N2 for ammonia synthesis by single-atom catalysts based on two-dimensional azulenocyanine monolayers

Abstract

In this paper, we systematically investigate the potential of a series of transition metal atoms embedded in two-dimensional azulenocyanine monolayer to form TM@Az as single-atom catalysts for electrocatalytic N₂ reduction to NH₃ (NRR) through first-principles calculations. Thermodynamic and electrochemical stabilities of these materials are studied to evaluate their stability, and the high-throughput screening method is used to screen out the potential candidate of Mo@Az. The detailed reaction mechanism of Mo@Az indicates that the first protonation step is the potential-determining step (PDS) with the limiting potential of −0.53 V. Then, the charge density differences, spin density, charge changes, electronic properties, and selectivity are explored. Notably, the Mo@Az demonstrates the high selectivity toward electrocatalytic nitrogen reduction reaction. We hope that this study can open a door for the development of azulenocyanine materials in the field of catalysis. Additionally, it is anticipated that our research will offer valuable insights and references for designing and developing single-atom catalysts toward electrochemical reduction of N₂ to NH₃.