Study on optical properties of alkali metal doped g-C3N4 and their photocatalytic activity for reduction of CO2

Abstract Alkali metal (Li, Na, K and Rb) doped g-C3N4 were prepared by water bath heating and high temperature calcination method. Photoelectric properties were studied by first-principles calculations and experiments. Computational results show that absorption spectra of Rb doped g-C3N4 increases significantly in the wavelength range of 500-1100 nm, which is consistent with the UV-vis spectrum. Rb doped g-C3N4 showed the best photo-reduction CO2 performance, with a CO productivity more than three times higher compared with bulk g-C3N4. This work provides a guiding significance for construction of doped g-C3N4 materials applied in fields of environmental remediation, energy conversion and medical imaging.