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

Abstract Boron carbide/graphitic carbon nitride (B 4 C/g-C 3 N 4 ) 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 B 4 C/g-C 3 N 4 loaded with Pt co-catalyst was evaluated using CO 2 conversion to CH 4 with H 2 as the hydrogen source and reductant under visible light irradiation. The coupling of p-type B 4 C with n-type g-C 3 N 4 significantly improved the performance of photocatalytic CO 2 reduction; with the optimum B 4 C mass fraction of 1/6, the composite photocatalyst showed approximately 6 and 8 times higher CH 4 generation rate than g-C 3 N 4 and B 4 C, respectively. The enhancement was attributed to efficient photo-excited electron/hole separation due to the formation of internal electric field at the p-B 4 C/n-C 3 N 4 interface.