Thermal coupled photocatalysis to enhance CO₂ reduction activities on Ag loaded g-C₃N₄ catalysts

The contribution of heat input in traditional photocatalytic processes is rarely studied. Herein, a series of the Ag nanoparticles deposited g-C₃N₄ (Ag-CN) was prepared by photochemical method and used for photocatalytic CO₂ reduction with the assistance of thermal energy. The photocatalytic properties were investigated under light-emitting diode light (420 nm, on the order of solar intensity) irradiation at temperatures up to 200 ºC, confirming that the CO evolution rate was strongly dependent on the reaction temperature. The CO production reached to a maximum value of 179.6 μmol•g⁻¹•h⁻¹ (about 4.2 times higher than that of CN) on the 20%Ag loaded CN at 190 °C although negligible photocatalytic activity was observed under light illumination at ambient temperature. The enhancement of the temperature could not only improve the transfer rate and energy of the excited electrons, but also increase the population of the activated molecules, which might contribute to the enhancement on the CO production. Our finding provides an alternative way for integrating infrared light (accounting for ~50% of the solar light) in photocatalysis considering the thermal effect of the infrared light.