Decoration of Bi2Se3 nanosheets with a thin Bi2SeO2 layer for visible-light-driven overall water splitting

Exploring and developing novel semiconductor photo-catalysts for visible-light-driven water splitting are of great scientific significance to solve energy and environmental problems. Herein, Bismuth Selenide (Bi₂Se₃) nanosheets decorated with a thin layer of Bi₂SeO₂ to form Bi₂Se₃/Bi₂SeO₂ nanocomposites were successfully prepared using a conventional reflux and heating method. Fabricated Bi₂Se₃/Bi₂SeO₂ heterojunctions were characterized via X-ray diffraction, scanning electron microscopy, high resolution transmission electron microscopy and X-ray photoelectron spectroscopy. It has revealed that, the thickness of outer Bi₂SeO₂ layer can be tuned upon the annealing temperatures, which strongly influenced the performance of catalyst towards water splitting performances. Annealed at 200 °C, the Bi₂Se₃/Bi₂SeO₂ heterojunction with ～5 nm of Bi₂SeO₂ layer yielded the highest hydrogen production rate of 136 μmol g^?1 h^?1. This enhanced photo-catalytic activity was ascribed to the synergy effect between the Bi₂Se₃/Bi₂SeO₂ layer, increased the visible light absorbance capacity, adjustment of the band gap and accelerate the electron-hole separation efficiency. The results represent a simply solution-based method towards a material with high photo-catalytic performance through the appropriate regulation of the oxidation degree of Bi₂Se₃ nanosheets, promising their industrial applications.