Exploring the Catalytic Performance of Oxygen-Coordinated Single-Atom Catalysts for Nitric Oxide Electroreduction

Single-atom catalysts (SACs) have been successfully implemented in the electrochemical nitric oxide reduction reaction (NORR) for ammonia (NH 3 ) synthesis over the past years. Given the prominent impact of microstructures on the catalytic performance of SACs, a rational design of the catalyst structure is indispensable for regulating the catalytic properties. In this study, we systematically explored the catalytic activity of two emerging oxygen-coordinated SACs, carbonyl oxygen-coordinated M–O–C (M = Sc, Ti, V, Cr, Mn, Fe, Co, and Ni) and graphitic oxygen-coordinated M–O 4, toward electrocatalytic reduction of NO to NH 3 by means of density functional theory (DFT) calculations. Through detailed selectivity and surface Pourbaix diagram analyses, we finally identified four M–O–C (M = Cr, Mn, Fe, Ni) SACs as promising NORR electrocatalysts, wherein the Mn–O–C demonstrates superior catalytic activity for NH 3 formation, with a limiting potential of −0.36 V. Furthermore, the constant potential calculations show that the Mn–O–C SAC can attain a lower limiting potential of −0.12 and −0.20 V in acidic (pH = 1) and neutral (pH = 7) environments, respectively, when employing a biased potential of 0 V/RHE. These findings offer fundamental guidelines for the rational regulation of oxygen-coordinated SACs and pave the way for their applications in NORR.