Sulfur doping induced 3D hierarchical porous BiOI–Bi2S3 S-scheme heterojunction with regulated oxygen vacancies for a four-pronged enhanced photocatalytic degradation towards four representative pollutants

It is challenging and still difficult to adjust and boost the catalytic performance of photocatalysts via the synergistic achievement of heteroatom doping, vacancies engineering, morphology regulation, and appropriate structural design. Herein, we developed an efficient method to synthesize 3D hierarchical porous BiOI–BiS S-scheme heterojunction with oxygen vacancies (Ov-BBS) induced by sulfur doping and systematically investigated regulation of oxygen vacancies by sulfur doping and their effects on photocatalytic performance. Results showed that sulfur species promoted the formation of S-scheme heterojunction but depleted oxygen vacancies in Ov-BiOI. The optimal sulfur doped catalyst (Ov-BBS-0.1) exhibited excellent UV–vis light photocatalytic activity towards four representative pollutants, affording removal rate of 97.1 % for MB, 97.6 % for RhB, 99.4 % for Cr(VI), and 92.0 % for TC, respectively, which were higher than those of pristine BiS, BiOI, Ov-BiOI, Ov-BiOI/BiS mixture, Ov-BBS-0.05, and Ov-BBS-0.2. Deep characterizations and theoretical studies certified that the four-pronged enhancement strategy of 3D hierarchical porous structure, oxygen vacancies, sulfur doping and the constructed S-scheme heterojunction, not only enriched accessible active sites, but also promoted electronic polarization and modulated electronic structure, resulting in rapid separation and migration of photogenerated carriers. Moreover, considering the excellent stability and cyclic photocatalytic performance, the film prepared by pumping Ov-BBS dispersion was also satisfactory in the practical application of circulating sewage treatment. Overall, the present work provides a novel approach for the design of more photocatalysts with high efficiency.