It remains a great challenge to understand the role of oxygen vacancies in determining the photooxidation properties of semiconductors under visible-light irradiation. Herein, BiOCl with oxygen vacancies is proposed as an excellent model to study the relationship between oxygen vacancies and photooxidation properties. BiOCl nanosheets with abundant oxygen vacancies are synthesized via a facile solvothermal route. Theoretical and experimental results reveal that after the introduction of oxygen vacancies, a new electron donor level appears in the band gap of BiOCl, extending the absorption from the ultraviolet to the visible regime. As expected, BiOCl nanosheets with oxygen vacancies exhibit visible-light-driven photocatalytic activity towards oxygen evolution. In addition, BiOCl with abundant oxygen vacancies exhibits a higher visible-light photocurrent and more efficient photoinduced charge separation and transportation than BiOCl with a small number of oxygen vacancies. The introduction of oxygen vacancies on the surfaces of semiconductors provides a promising way to improve the visible-light photooxidation activity of photocatalysts.

A convenient hydrothermal intercalation/exfoliation method for large-scale manufacturing of bismuth telluride (Bi₂Te₃) nanosheets is reported here. Lithium cations can be intercalated between the layers of Bi₂Te₃ using the reducing power of ethylene glycol in the common hydrothermal process, and high quality Bi₂Te₃ nanosheets with thickness down to only 3–4 nm are obtained by removing lithium in the following exfoliating process. Scanning electron microscopy, transmission electron microscopy and Raman spectrum characterizations confirm that the high yield of Bi₂Te₃ nanosheets with good quality were successfully achieved and the sizes of the immense nanosheets reached 200 nm width and 1 μm length. This hydrothermal intercalation/exfoliation method is general, as it has been extended to other layered materials, such as Bi₂Se₃ and MoS₂. Our results suggest a simple route for the large-scale production of thin and flat Bi₂Te₃ nanosheets, which may be beneficial to further electronic and spintronics applications.