Probing into the\nCatalytic Activity of Single-Atom\nCatalysts for NO Oxidation by H<sub>2</sub>O<sub>2</sub> via the Tri-activity\nVolcano Plot

The recently emerging single-atom catalysts (SACs) are\nproposed\nas promising candidates for the catalytic oxidation of NO in the field\nof NO pollutant reduction from coal-fired power stations. However,\ndue to the lack of theoretical model guidance, achieving efficient\ncatalytic oxidation of NO at room temperature still remains a major\nconcern. Thus, in this study, the reaction pathways for the catalytic\noxidation of NO by OOH radicals on eight TM–N<sub>4</sub>–C\n(TM = Sc, Cr, Mn, Fe, Co, Ni, Cu, and Zn) were investigated based\non density functional theory calculations. Based on the Bronsted–Evans–Polanyi\nlinear relationship and microkinetic simulations, the activity volcano\nplot model for the catalytic oxidation of NO by OOH has been successfully\nestablished and validated. The Fe–N<sub>4</sub>–C and\nMn–N<sub>4</sub>–C catalysts showed higher reactivities\namong these catalysts. The energy barriers for the rate-determining\nsteps of these two catalysts were 0.14 and 0.30 eV, respectively,\nillustrating that catalytic oxidation of NO is feasible at room temperature.\nSignificantly, a tri-activity volcano plot was constructed based on\nthe unified activity descriptor of O adsorption energy for guiding\nthe design of SACs in H<sub>2</sub>O<sub>2</sub> catalytic oxidation\nof NO. The pathway of catalytic oxidation NO by OOH radicals is the\ndominant route in the system of SACs for the catalytic oxidation of\nNO by H<sub>2</sub>O<sub>2</sub>. The analysis of Bader charge and\nelectronegativity revealed a linear correlation between the structural\nproperties of the catalysts and the catalytic activity descriptor,\nwhich can be used to quickly predict the reactivity of SACs with different\ncoordination environments. This work provides a new pathway for the\ncurrent NO oxidation and guides future work on catalyst screening\nand experimental preparation.