Computational screening of g-CN supported transition metals single-atom catalysts for electrocatalytic NO reduction reaction.

Electrocatalytic nitric oxide reduction reaction (NORR) offers a promising approach for the efficient synthesis of ammonia (NH). Density functional theory (DFT) study was conducted to investigate the activity and selectivity of NORR on transition metal (TM-Cv-CN) single-atom catalysts (SACs) supported on graphitic carbon nitride. Initially, 13 stable SACs were screened based on thermodynamic and electrochemical stability. Subsequent analysis revealed that nine of these stable SACs could adsorb and activate NO molecules in the most stable N-terminal adsorption mode. Based on the stable N-terminal adsorption configuration on SACs, the possible reaction mechanisms for the electrocatalytic NO reduction to ammonia on nine SACs were studied. The results revealed that every elementary reaction in the most favorable path N-mixed-1 on Ti-Cv-CN was exothermic, demonstrating its highest catalytic activity. Additionally, the competitive hydrogen evolution reaction (HER) was effectively suppressed on Ti-Cv-CN, and the selectivity of the NH product was significantly higher compared to by-products such as NO, N, further confirming the excellent electrocatalytic NORR selectivity of Ti-Cv-CN. Moreover, charge and bonding analysis indicated that Ti atom in Ti-Cv-CN not only acts as an electron donor to promote NO activation but also serves as an electron channel for rapid charge transfer between adsorbed intermediates and other substrate atoms.