Thermal coupled photocatalysis over Pt/g-C3N4 for selectively reducing CO2 to CH4 via cooperation of the electronic metal–support interaction effect and the oxidation state of Pt

Pt nanoparticle-loaded g-C3N4 (Pt/CN) that consisted of integrating Pt0 and Pt2+ species was prepared for selectively reducing CO2 to CH4 with H2O by thermal coupled photocatalysis. A strong electronic metal-support interaction was constructed between Pt nanoparticles and the g-C3N4 substrate, which limited the activity for CO evolution and improved the charge transfer from g-C3N4 to Pt for selective CH4 production. The formed Pt2+ species in the Pt nanoparticles completely suppress the side reaction of H2 production from reducing H2O. Moreover, a moderate heat input in the photocatalytic reaction facilitated the transfer of the photogenerated electrons from Pt nanoparticles to CO2, which further increased the photocatalytic activity for CH4 evolution. As a result, a significant enhancement of CO2 methanation performance (∼100 % selectivity, 14.8 μmol g−1 h−1) was realized on a 2 % Pt-loaded g-C3N4 photocatalyst under low intensity light-emitting diode (420 nm, on the order of solar intensity) irradiation at 125 °C.