Abstract:

A CdS/g-C₃N₄ composite was prepared by hydrothermal method using cadmium sulfide （CdS） and graphitic carbon nitride （g-C₃N₄） as precursors. This CdS/g-C₃N₄ composite material had high specific surface area and rich mesoporous structure. The average grain size was 11.0 nm and the band gap energy was 2.43 eV. The UV-visible diffuse reflectance spectrum showed a significant red shift, and the spectral absorption range became wider. The typical emission peak intensity in fluorescence spectrum was significantly lower than that of the pure-phase material, which realized the efficient photoelectron-hole separation. Congo red （CR） dye was used as the target pollutant to carry out photocatalytic experiments. When 30 mg CdS/g-C₃N₄ composite was added to 100 mL of CR dye solution with a mass concentration of 20 mg/L at pH of 7.0, the removal percentage of CR was 95.99%, and the CdS/g-C₃N₄ composite material showed good stability. Mechanism analysis showed that the efficient degradation of CR dye was achieved under the synergistic effect of electric field and highly active superoxide anion radicals （·O₂^-） in the S-scheme charge transfer mechanism.

Key words: CdS/g-C₃N₄, composite material, photocatalysis, congo red, heterojunction