Synthesis and characterization of enhanced visible light-driven mesoporous TiO2-WO3/Bi2WO6 nanosheet photocatalyst

The construction of matchable multi-heterojunction with appropriate morphology provides a good strategy for improving the performance of semiconductor photocatalyst in degrading organic pollutants. Herein, binary WO3/Bi2WO6 nanosheets coupled with various contents of mesoporous anatase TiO2 nanoparticles for constructing TiO2/WO3/Bi2WO6 heterojunction composite photocatalysts are hydrothermally fabricated. The investigation on structure and properties in the TiO2/WO3/Bi2WO6 ternary photocatalysts in terms of the incorporation of TiO2 is systematically conducted by using characterization techniques. The results show that the TiO2/WO3 /Bi2WO6 ternary composite at the optimized Ti/W ratio of 1:2 has the highest visible light-irradiated MB degradation, which is 9.5 times and 2.8 times that of pure TiO2 and pristine WO3/Bi2WO6 nanosheets, respectively. The effective charge separation between TiO2 and WO3/Bi2WO6 has been confirmed by PL and current-voltage (I-V) characteristics. A possible mechanism is clarified through the active species trapping experiments using various scavengers, indicating that photogenerated holes and center dot OH radicals play a key role. The enhanced photocatalytic activity can be ascribed to the synergistic effect of the unique structure with some favorable properties, including the elevation of the separation efficiency of photoinduced electron-hole pairs at the multi-heterojunction interfaces with appropriate band structures as well as more active adsorption sites of mesoporous/nanosheet microstructure in the degradation process. This research may provide a simple method for design and preparation of novel heterojunction photocatalysts for enhanced visible light-driven photocatalytic activity.

Automated summary

The construction of a matchable multi-heterojunction with appropriate morphology is an effective strategy for improving the performance of semiconductor photocatalysts in degrading organic pollutants. In this study, TiO2/WO3/Bi2WO6 heterojunction composite photocatalysts were fabricated through a hydrothermal method using binary WO3/Bi2WO6 nanosheets coupled with various contents of mesoporous anatase TiO2 nanoparticles. The investigation on the structure and properties of the TiO2/WO3/Bi2WO6 ternary photocatalysts revealed that the optimized Ti/W ratio of 1:2 resulted in the highest visible light-irradiated MB degradation, with a degradation rate 9.5 times and 2.8 times higher than that of pure TiO2 and pristine WO3/Bi2WO6 nanosheets, respectively. The enhanced photocatalytic activity can be attributed to the improved separation efficiency of photoinduced electron-hole pairs and the presence of more active adsorption sites in the unique multi-heterojunction structure.