Persulfate Activation of Photocatalysts Based on S-Scheme Bi3NbO7/BiOBr0.75I0.25 Nanosheet Heterojunctions for Degradation of Organic Pollutants

Abstract

Photocatalytic activation of persulfate has been receiving much attention in the field of wastewater treatment. In this work, the Bi3NbO7/BiOBr0.75I0.25 nanosheet S-scheme heterojunctions were synthesized by the solvothermal method to activate persulfate. The degradation rates of rhodamine B (RhB) and TC by 0.05Bi3NbO7/BiOBr0.75I0.25 were 95.4 and 74.7% in 2 h, respectively, indicating that 0.05Bi3NbO7/BiOBr0.75I0.25 nanosheet heterojunctions have good photocatalytic activity. The synergistic effect between persulfate and the 0.05Bi3NbO7/BiOBr0.75I0.25 photocatalyst was investigated under different persulfate contents, pH values, and light conditions. The RhB degradation rate of 0.05Bi3NbO7/BiOBr0.75I0.25 activation persulfate is more than twice that of 0.05Bi3NbO7/BiOBr0.75I0.25, and the range of pH adaptation is wide. Radical quenching experiments showed that h+, ·O2–, and ·OH were the important active groups. Persulfate and catalysts produce a synergistic effect, which is S2O82– reacting with e– to form ·SO4– in the photocatalytic process. Meanwhile, the formation of ·SO4– accelerates the process of photocatalytic reaction. This work provides ideas for the design of efficient and pollution-free photocatalysts for the activation of persulfate.