Persulfate Activation of Photocatalysts Based on S-Scheme Bi₃NbO₇/BiOBr_0.75I_0.25 Nanosheet Heterojunctions for Degradation of Organic Pollutants

Photocatalytic activation of persulfate has been receiving much attention in the field of wastewater treatment. In this work, the Bi 3 NbO 7 /BiOBr 0.75 I 0.25 nanosheet S-scheme heterojunctions were synthesized by the solvothermal method to activate persulfate. The degradation rates of rhodamine B (RhB) and TC by 0.05Bi 3 NbO 7 /BiOBr 0.75 I 0.25 were 95.4 and 74.7% in 2 h, respectively, indicating that 0.05Bi 3 NbO 7 /BiOBr 0.75 I 0.25 nanosheet heterojunctions have good photocatalytic activity. The synergistic effect between persulfate and the 0.05Bi 3 NbO 7 /BiOBr 0.75 I 0.25 photocatalyst was investigated under different persulfate contents, pH values, and light conditions. The RhB degradation rate of 0.05Bi 3 NbO 7 /BiOBr 0.75 I 0.25 activation persulfate is more than twice that of 0.05Bi 3 NbO 7 /BiOBr 0.75 I 0.25, and the range of pH adaptation is wide. Radical quenching experiments showed that h +, ·O 2 –, and ·OH were the important active groups. Persulfate and catalysts produce a synergistic effect, which is S 2 O 8 2– reacting with e – to form ·SO 4 – in the photocatalytic process. Meanwhile, the formation of ·SO 4 – accelerates the process of photocatalytic reaction. This work provides ideas for the design of efficient and pollution-free photocatalysts for the activation of persulfate.