Electrocatalysis of NO to NH₃ on transition-metal doped two-dimensional BC₂N: a DFT study

Coal-fired power plants widely employ low-NOx combustion and selective catalytic reduction (SCR) techniques to mitigate NOx emissions. However, the former compromises combustion stability, while the latter consumes substantial NH₃. In this study, the electrochemical conversion from nitric oxide (NO), the main component of NOx, to NH₃ offers a sustainable strategy to simultaneously reduce pollutant emissions and recover valuable nitrogen resources. Herein, density functional theory (DFT) calculations are employed to systematically investigate the electrocatalytic NO reduction reaction (NORR) on two-dimensional BC₂N monolayers doped with single transition-metal atoms (Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Nb, Mo, Ru, Rh, and Pd) at B vacancy sites. All doped configurations are thermodynamically stable, with Co@BC₂N further confirmed by ab initio molecular dynamics (AIMD) simulations to maintain structural integrity at 300 K. The calculated free energies indicate that NO adsorption dominates over the competing hydrogen evolution reaction (HER), ensuring high NO selectivity. Among all candidates, Co@BC₂N exhibits the lowest rate-determining free energy barrier (0.10 eV) and favorable charge transfer between Co-3d and NO-2p orbitals, facilitating efficient NO activation and hydrogenation. This study highlights Co@BC₂N as an outstanding active and stable NORR catalyst, offering atomic-level insight for the rational design of next-generation NO-to-NH₃ electrocatalysts.