Abstract:

AgBr/C₃N₅ composite was prepared by in-situ precipitation of AgBr on the surface of nitrogen-rich carbon nitride （C₃N₅）. The crystal phase, chemical composition, elemental composition, spectral absorption and photoelectron-hole separation of the composite were characterized by X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FTIR）, X-ray photoelectron spectroscopy （XPS）, ultraviolet-visible diffuse reflectance spectroscopy （UV-vis DRS） and photoluminescence spectroscopy （PL）. The construction of AgBr and C₃N₅ heterojunction could broaden the spectral response range, realize the efficient separation of photoelectrons and holes, and thus improve the photocatalytic performance. The photocatalytic performance of the composite material was studied by simulating inorganic ammonia nitrogen wastewater with NH₄Cl solution. The dosage of the composite material was 0.10 g, the initial mass concentration of NH₄Cl solution was 100 mg/L, and the initial pH was 10.0. The removal rate of ammonia nitrogen by the composite material reached 90.27% after 60 min of simulated visible light irradiation. After 5 cycles, the removal rate of ammonia nitrogen only declined by 0.12%. The composite material showed good photocatalytic performance and stability. The Z-scheme mechanism effectively retained the reduction and oxidation activities of photoelectrons and holes, which could change O₂ and H₂O to active groups such as superoxide radicals （·O₂^-） and hydroxyl radicals （·OH）, respectively, achieving efficient removal of inorganic ammonia nitrogen.

Key words: nitrogen-rich carbon nitride, composite material, visible light, inorganic ammonia nitrogen