Photocatalytic CO2 reduction over B4C/C3N4 with internal electric field under visible light irradiation

Boron carbide/graphitic carbon nitride (B4C/g-C3N4) p-n hetero-junction photocatalyst with an internal electric field was synthesized by a facile solvent evaporation method and characterized by field emission scanning electron microscope (FESEM), UV-Vis diffuse reflectance spectra (UV-Vis DRS), photoluminescence spectra (PL), etc. Photocatalytic activity of the composite B4C/g-C3N4 loaded with Pt co-catalyst was evaluated using CO2 conversion to CH4 with H2 as the hydrogen source and reductant under visible light irradiation. The coupling of p-type B4C with n-type g-C3N4 significantly improved the performance of photocatalytic CO2 reduction; with the optimum B4C mass fraction of 1/6, the composite photocatalyst showed approximately 6 and 8 times higher CH4 generation rate than g-C3N4 and B4C, respectively. The enhancement was attributed to efficient photo-excited electron/hole separation due to the formation of internal electric field at the p-B4C/n-C3N4 interface.