Highly Efficient Visible Light Photocatalytic Activities in Self-Assembled Metastable TiO2/Bi4MoO9 Heterojunctions

Metastable TiO2/Bi4MoO9 heterojunctions are synthesized using a hydrothermal method. TiO2 nanoparticles, which are used as templates in the hydrothermal process, can induce the heterogeneous nucleation and 1D preferential growth of Bi4MoO9 to form TiO2/Bi4MoO9 heterojunctions. The TiO2/Bi4MoO9 heterojunctions exhibit very efficient visible-light photocatalytic activity, which is much higher than those of TiO2 nanoparticles, Bi4MoO9 microcubes, and TiO2/Bi2MoO6 composites. This could be mainly ascribed to the synergistic effects of the band structure matching and the unique microstructure between TiO2 nanoparticles and Bi4MoO9 nanobelts in the heterojunctions. The Bi4MoO9 nanobelts with approximate to 150 nm in width promote the production of photogenerated electron-hole pairs due to its narrow bandgap. The TiO2 nanoparticles embedded into Bi4MoO9 nanobelts still remain small size, large specific surface area, and high crystallinity. These not only facilitate the transfer of photogenerated holes from Bi4MoO9 nanobelts to TiO2 nanoparticles, but also improve the holes capture rate on the surface of the heterojunctions.