Construction of BiVO4/Bi2WO6/WO3 heterojunctions with improved photocatalytic capability in elimination of dye and antibiotics and inactivation of E. coli

Background: Recently, semiconductor photocatalysts have been known as one of most promising strategies for environmental purification and remediation due to the rapid and nonselective oxidation of a broad range of organic pollutants. Methods: In this article, BiVO4/Bi2WO6/WO3 ternary heterojunction with cascade energy band alignment has been proposed and prepared by microwave-assisted hydrothermal reaction. Significant findings: The constructed ternary composite shows a broader absorption spectrum compared with the binary BiVO4/Bi2WO6 and pure BiVO4 samples. In addition, the ternary composite with gradient energy band alignment can accelerate the electron-hole separation and charge carrier transfer leading to decreased photoluminescence (PL) intensity and lifetime. As a result, the BiVO4/Bi2WO6/WO3 heterostructured composite can display higher photocurrent and possess an enhanced performance in the visible-light-driven degradation of methylene blue (MB). Our results indicate that the optimal molar ratio of BiVO4:Bi2WO6:WO3 is found to be 0.375:0.375:0.25, revealing the best photocatalytic activity. The ternary composite with optimal molar ratio exhibits a 50.9% greater degradation rate (rate constant (k) =0.0283 min-1) over the BiVO4 (k = 0.0139 min-1) for the photodegradation of MB. Besides, the resultant ternary system also shows excellent photocatalytic performance in the degradation of antibiotics and antibacterial capability with great biocompatibility.

Automated summary

In this article, a ternary heterojunction composite of BiVO4/Bi2WO6/WO3 with cascade energy band alignment was proposed and prepared. The ternary composite showed a broader absorption spectrum and enhanced electron-hole separation and charge carrier transfer. The optimal molar ratio of BiVO4:Bi2WO6:WO3 was found to be 0.375:0.375:0.25, displaying the best photocatalytic activity with a 50.9% greater degradation rate for methylene blue.