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 (Bi 2 Se 3 ) nanosheets decorated with a thin layer of Bi 2 SeO 2 to form Bi 2 Se 3 /Bi 2 SeO 2 nanocomposites were successfully prepared using a conventional reflux and heating method. Fabricated Bi 2 Se 3 /Bi 2 SeO 2 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 Bi 2 SeO 2 layer can be tuned upon the annealing temperatures, which strongly influenced the performance of catalyst towards water splitting performances. Annealed at 200 °C, the Bi 2 Se 3 /Bi 2 SeO 2 heterojunction with ∼5 nm of Bi 2 SeO 2 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 Bi 2 Se 3 /Bi 2 SeO 2 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 Bi 2 Se 3 nanosheets, promising their industrial applications.