Herein, an efficient broad-spectrum WS 2 /BiOBr heterostructure with ultrathin nanosheet was successfully prepared by one-pot hydrothermal route. The self-assembled flower-like WS 2 /BiOBr nanostructure was formed by few-layer WS 2 and BiOBr nanosheets. The optimized heterojunction presented broad-spectrum high-efficiency photocatalytic activity towards the removal of various pollutants under visible-light irradiation, including organic dyes, antibiotics and phenols. This efficiency was linked to high light harvesting combined with effective charge separation/transfer. Meanwhile, the degradation efficiencies varied with nature of the pollutant decreased in the following order: LR5B (99%) > MNZ (97%) > TC (92%) > OTC (92%) > RhB (90%) > CIP (83%) > MB (78%) > MO (62%) > bisphenol (42%) > phenol (40%). The photocatalytic process of ciprofloxacin was explored, and the results indicated that high ciprofloxacin concentrations, low pH values and elevated concentrations of ions (PO 4 3− , HPO 4 2‐ , H 2 PO 4 − , and Cu 2+ ) restrained the photocatalytic performances. Trapping experiments and ESR revealed the significant contribution of holes (h + ) in the mechanism, where both superoxide radicals ( O 2 − ) and hydroxyl radicals ( OH) acted as assistants. Overall, this work could offer a new protocol for the design of highly efficient heterostructure photocatalysts for environmental remediation.
In this study, a novel 0D/2D WS 2 /BiOBr heterostructured photocatalyst with rich oxygen vacancies was fabricated by a hydrothermal method. The WS 2 QDs/BiOBr-10 heterostructures exhibited a maximum removal rate of 92% towards ciprofloxacin (CIP) within 100 min under visible-light irradiation, which was 2.63- and 2.02- folds higher activity than that of pristine BiOBr and WS 2 QDs/BiOBr-10 with poor oxygen vacancies, respectively. In addition, the removal efficiencies of this photocatalyst towards various pollutants were 99% (Lanasol Red 5B), 95% (Rhodamine B), 85% (metronidazole), 96% (tetracycline) and 41% (Bisphenol A), respectively. Besides, the simultaneous photocatalytic degradation showed the competitive interactions between these organic contaminants for the active species, decreasing the removal efficiency for CIP. However, the simultaneous photocatalytic oxidation of CIP and reduction of Cr(VI) improved the utilization efficiency of photo-induced electrons and holes, resulting in high removal efficiencies for both CIP and Cr(VI). Three-dimensional excitation-emission matrix fluorescence spectra (3D EEMs) were used to investigate the degradation of CIP molecules. The synergistic effect of heterostructure and oxygen vacancies greatly assisted in the removal of organic pollutants, attributing to the enhanced visible-light harvesting and effective separation of photo-induced electron–hole pairs. Furthermore, trapping experiments and ESR results demonstrated that the CIP removal was dominated by the direct oxidation of holes (h + ), whereas the hydroxyl radicals ( OH) and superoxide radicals ( O 2 − ) acted as auxiliary active species. This study provides a new way to rationally design and construct active 0D/2D pattern heterojunction photocatalysts for environmental remediation.
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