Asymmetric Co-Ov-Ti in hierarchical platelet-spherical structure Co NCs/Ti3C2 MXene for simultaneous and competitive catalytic oxidation of Hg0 and CO in flue gas

Among the diverse pollutants emitted from coal-fired and non-ferrous metal smelting flue gas, Hg 0 and CO have emerged as globally concerning environmental pollutants. However, the simultaneous abatement of multiple pollutants remains a critical challenge to be addressed. In this study, cobalt nanoclusters (Co NCs) were anchored on the terminal oxygen of Ti-O on Ti 3 C 2 MXene and formed asymmetric oxygen vacancies Co-Ov-Ti via a one-step hydrothermal method, yielding Co NCs/Ti 3 C 2 MXene with a morphology of hierarchical nanosheet-assembled spheres for Hg 0 and CO catalytic oxidation. Co NCs/Ti 3 C 2 MXene exhibited excellent 44 % and 52 % of Hg 0 and CO simultaneous removal efficiency at the optimal temperature of 250 °C, respectively. DFT calculations combined with energy barrier modeling were employed to investigate the reaction pathways and energy variations during the catalytic oxidation of Hg 0 and CO. Specifically, Hg 0 oxidation follows the Eley-Rideal mechanism, with a rate-determining energy barrier of 2.11 eV, while CO oxidation adheres to the Langmuir-Hinshelwood mechanism, featuring a rate-determining barrier of 0.17 eV. In the co-catalytic oxidation process, competitive adsorption between Hg 0 and CO was observed, primarily manifested as competition for Ov on the catalyst surface. This study provides a novel strategy for the synergistic control of multi-pollutants in industrial flue gas.