Comprehensive study of growth mechanism and photoelectrochemical activity of BiVO4/Bi2S3 nanowire composite.

A BiVO4/Bi2S3 composite comprising Bi2S3 nanowires on top of BiVO4 film was prepared via hydrothermal reaction. Because additional Bi3+ ions were not delivered during the reaction, the BiVO4 served as the Bi3+ ion source for the development of Bi2S3. Detailed growth mechanism of the nanowire was elucidated by an analysis of the concentration gradient of Bi3+ and S2- ions during the reaction. The in situ growth was followed by the etching of BiVO4 to Bi3+ and VO43- ions and regrowth to Bi2S3, which resulted in the rapid evolution of nanowires on the BiVO4 substrate. The fabricated BiVO4/Bi2S3NW composite exhibited an improved photoelectrochemical activity compared to other Bi2S3 samples. The improved efficiency was mainly attributed to both improved charge separation and effective adhesion obtained by the in situ growth.