Main-Group p-Block Metal-Doped C₃N Monolayers as Efficient Electrocatalysts for NO-to-NH₃ Conversion: A Computational Study

The electrochemical NO reduction reaction (NORR) toward NH₃ synthesis not only helps address issues of air pollution but also holds significant energy and economic value, making it an innovative method with broad application prospects. However, designing NORR electrocatalysts that are both highly active and selective remains a formidable challenge. Herein, we study the main-group p-block metal (M = Al, Ga, and In)-doped C₃N monolayers as promising single-atom catalysts (SACs) for NORR through spin-polarized first-principles calculations. Our results show that Al@V_CC, Al@V_CN, Ga@V_CC, and Ga@V_CN systems are not only stable but also exhibit metallic characteristics, ensuring effective charge transfer during the NORR process. Moreover, nitric oxide (NO) can be strongly chemisorbed and activated on all four candidates with adsorption free energies ranging from -0.83 to -1.59 eV and then spontaneously converted into NH₃ without the need for any applied voltage. More importantly, Ga@V_CN possesses a well-suppressed ability for the formation of H₂/N₂O/N₂ byproducts, indicating excellent NH₃ selectivity. These findings not only offer a promising electrocatalyst for the NO-to-NH₃ conversion but also highlight the great potential of main-group metals as SACs for electrochemical reactions.