Bismuth vacancy mediated Bi2WO6 nanosheets/BiOBr nanoflowers S-scheme heterostructure for efficient photocatalytic degradation of antibiotics

In this work, we successfully created Bi2WO6/BiOBr S-scheme 2D/3D heterostructures with metallic bismuth vacancies (VBi-BB) through a carefully designed hydrothermal method. This study comprehensively investigates the structure, morphology, and chemical composition of the heterostructures. It also explores photocatalytic breakdown of organic contaminants and studies the influence of environmental circumstances on this procedure. The optimal VBi-BB-3 heterojunction demonstrates exceptional photocatalytic activity in breaking down oxytetracycline (OTC), achieving a degradation rate of almost 99% in just 60 min, and the first-order kinetic constant is 0.038 min-1, which are 1.59 and 6.91 times higher than those of BOB and BWO, respectively. The exceptional performance of VBi-BB heterojunctions can be attributed to the deliberate inclusion of metal vacancy defects, the formation of distinct 2D/3D surface morphologies and S-scheme heterojunctions, which leads to precise adjustment of the energy band structure, the increase in available surface active sites, and the improvement of charge separation capability. The major active species are confirmed to be h+ and center dot O2-. Finally, we proposed the charge transfer mechanism for the photocatalytic process of the VBi-BB S-scheme heterojunction and OTC degradation pathways. This study offers a potential pathway for the advancement of highly effective photocatalysts and subsequent environmental remediation.