A first-principles study of nitric oxide electroreduction on transition metal monolayers supported on Mo₂N

The electrochemical NO reduction reaction (NORR) offers a dual-functional strategy for NO removal and NH₃ synthesis. In this study, we systematically evaluated the NORR catalytic activity of transition metal (TM = Ni, Cu, Pd, Ag, Pt, Au) monolayers supported on Mo₂N (TM_ML/Mo₂N) using density functional theory (DFT). Our calculations identify that the electronic structure of these composite catalysts can be fine-tuned at the atomic level, thereby promoting NO adsorption and activation through an electron donation/backdonation mechanism. Cu_ML/Mo₂N, Ag_ML/Mo₂N, Pt_ML/Mo₂N and Au_ML/Mo₂N stand out as promising NORR candidates, with low U_L of -0.11, -0.13, -0.01, and -0.09 V for the PDSs (*NO hydrogenation). The electron redistribution and epitaxial strain in the heterojunction modulate the d-band center (ε_d) of TM monolayers. The ε_d serves as a screening indicator that optimizes the adsorption and desorption of intermediates and governs the NORR activity, thereby revealing a clear electronic structure-activity relationship. Thus, our findings provide a design principle for novel electrocatalysts, thereby contributing to both the theoretical understanding and practical application of two-dimensional materials in catalysis.