Novel dual S-scheme BiOI/AgI/Bi2WO6 heterojunction with enhanced photocatalytic activity for highly efficient removal of organic pollutants

To improve the catalytic performance of Bi2WO6, a dual S-scheme BiOI/AgI/Bi2WO6 ternary heterojunction photocatalyst was successfully constructed. Under visible light irradiation, 93.6% of 2,4-dinitrophenylhydrazine (2,4-DNPH) was removed by BOI/AI/BWO within 30 min, and the apparent rate constant was 30 times that of pure Bi2WO6. In addition, the methyl orange (MO) and tetracycline (TC) degradation rates were 87% and 94%, respectively. Therefore, BOI/AI/BWO exhibited more remarkable photocatalytic performance for the elimination of organic pollutants and aqueous solution containing antibiotics. Cyclic voltammetry test indicated that ternary heterojunction photocatalyst can able to provide more active surface area. Quenching experiments and electron paramagnetic resonance (EPR) analysis revealed that center dot O-2(-) and h(+) are main active species. Characterization test and mechanism analysis indicated that excellent photocatalytic performance of ternary heterostructure was ascribed to dual S-scheme charge transfer mechanism leaded to efficient photoexcited carrier separation and strong redox capacity. This research could provide a new strategy to design high-efficiency dual S-scheme photocatalyst for environmental remediation.