Preparation of Hollow SiO2@BiOI Nanocomposites and Their Photocatalytic Performance in Ammonia Nitrogen Degradation

Hollow SiO2 microsphere-supported bismuth oxyiodide (BiOI) nanocomposites were prepared using Bi(NO3)3 · 5H2O and KI as the precursors of BiOI at 80 °C in an aqueous solution by the liquid chemical deposition method. The BiOI nanosheets with the thicknesses of 25–40 nm and the widths of 1–2 μm were deposited on the hollow SiO2 microsphere surfaces. There were interactions between the BiOI nanosheets and hollow SiO2 microspheres, which enlarged the ban gap of the BiOI nanosheet as compared with the pure BiOI. The band gap energy increased with the increase in SiO2/BiOI weight ratios. The hollow SiO2@BiOI nanocomposites showed high photocatalytic activity in ammonia nitrogen degradation when the photocatalytic degradation reaction was performed in aqueous solution under visible light irradiation. The degradation extent of ammonia nitrogen was upto 81% when the ammonia nitrogen degradation reaction was photocatalyzed by the hollow SiO2@BiOI(100:10) nanocomposite at an initial concentration of ammonia nitrogen of 10 mg L−1 and 25 °C for 4 h. The reaction kinetics of ammonia nitrogen degradation was well simulated by the first-order reaction model.