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

Abstract

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.