Photocontrolled heterojunctions constructed from holmium single atom modified Mg1.2Ti1.8O5/g-C3N4 with enhanced photocatalytic CO2 conversion

Photocontrolled composites are worth studying because they exhibit different types of heterojunctions and tunable characteristics under different wavelengths of light. Here, photocontrolled heterojunctions constructed from Ho single atom modified Mg1.2Ti1.8O5/g-C3N4 exhibit different photocatalytic product selectivities and electron transfer directions under visible and ultraviolet light irradiation, indicating different photocatalytic mechanisms, both of which exhibit excellent photocatalytic performance. The results of XAFS, in situ XPS, and fs-TAS indicated that Ho coordinated with N and O, and preferentially combined with g-C3N4 to form more N vacancies, which was beneficial for charge transfer and CO2 adsorption. The (5)G(3)(H-3(6))/K-3(7)((5)G(4))/(5)G(5)/(5)G(6)(F-5(1)) -> I-5(8) emissions can be absorbed by Mg1.2Ti1.8O5/g-C3N4 composites, improving the light capture capability. The synergistic effects of Ho and Mg1.2Ti1.8O5/g-C3N4 composites can reduce the Delta G of the key rate-determining step CO2* -> COOH*.