Novel porous structure enhances the photocatalytic performance of Bi5O7I nanosheet

Designing an effective microstructure to further optimize the separation efficiency of bulk and in-plane charge carriers of 2D semiconductor materials is of great significance for optimal photocatalytic efficiency. In this paper, a porous Bi5O7I nanosheet with abundant oxygen vacancies was constructed by controlling the iodine removal process under inert atmosphere conditions to optimize the photocatalytic performance. By controlling the proportion of raw materials, the oxidation capacity of the solvent in the hydrothermal reaction can be adjusted to oxidize bismuth to a higher chemical valence state, which can skillfully promote the further oxidation and sublimation of iodine at high temperature to achieve the pore-building effect. Meanwhile, the samples prepared under an inert atmosphere not only exhibited a typical two-dimensional porous structure but also displayed abundant oxygen vacancies, compared with the samples prepared under a traditional air atmosphere. Furthermore, the 2D porous structure reduced the recombination probability of in-plane charge carriers, presented weak charge transfer resistance, and improved redox capacity due to the loss of iodine. In particular, the sample calcined at 450 °C with 20 nm pores uniformly distributed on the surface exhibited the best photocatalytic degradation activity and stability. The preparation of porous nanosheets provides a reference for improving the in-plane charge carrier separation efficiency of two-dimensional semiconductor materials, and is conducive to the design and preparation of bismuth-based semiconductor materials with excellent photocatalytic performance.