Persulfate Activation of Photocatalysts Based on S-Scheme Bi₃NbO₇/BiOBr_0.75I_0.25 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 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.

Generation of •OH and •O2– Radicals by a Bi2O3-Nanoparticle/Bi4O5Br2 Type-II Heterojunction for Photocatalytic Degradation of Organic Molecules

“…Classical layered ternary compounds, bismuth oxyhalides (Bi m O y X n , X = Cl, Br, or I) composed of [Bi 2 O 2 ] 2+ layers sandwiched between two slabs of halogen atoms, are a promising class of photocatalysts for improvements in the environment and energy conversion, and Bi 4 O 5 Br 2 exhibits great potential for practical application in environmental and energy areas in view of its suitable conduction band structure, tunable morphologies, high photostability, visible light response, and relatively negative conduction band energy. − Nevertheless, confined by the high photogenerated charge recombination efficiency, the photocatalytic activity of Bi 4 O 5 Br 2 is not high enough for application and needs to be greatly enhanced.…”