Synthesis of band gap-tunable alkali metal modified graphitic carbon nitride with outstanding photocatalytic H2O2 production ability via molten salt method

Abstract Band gap-tunable alkali metal modified graphitic carbon nitride was prepared by a molten salt method. X-ray diffraction, N2 isothermal sorption, ultraviolet-visible spectroscopy, scanning electron microscope, X-ray photoelectron spectroscopy and photoluminescence were used to characterize the obtained catalysts. The photocatalytic H2O2 production ability of as-prepared catalyst was investigated. The results indicate that K+ and Na+ are doped into g-C3N4 lattice simultaneously by the molten salt method. Alkali metal modification not only promotes the specific surface area, visible light absorption and separation of electron-hole pairs, but tunes the conduction band and valence band edge positions of as-prepared catalysts by controlling the weight ratio of eutectic salts to melamine. The tunable band edge positions result in the photocatalytic H2O2 production from “single channel pathway” to “two channel pathway”, leading to the promoted H2O2 production ability.