Enhanced photocatalytic activity of g-C3N4/Bi2WO6 heterojunction via Z-scheme charge-transfer mechanism

Abstract

In this study, g-C3N4/Bi2WO6 (CN/BWO) photocatalytic composite materials were prepared using a combination of calcination and solvothermal methods. The coiled sheet CN and the nanosheet BWO are coupled to form Z-scheme semiconductor junctions. For the close alignment between BWO conduction band (CB) and CN valence band (VB), photogenerated electrons originating from the BWO CB readily recombine with holes from the CN VB, which results in the accumulation of photogenerated holes in the BWO VB, exhibiting remarkable oxidation capability, and photogenerated electrons in the CN CB, displaying strong reducibility. This mechanism plays a pivotal role in the generation of ·O2– and ·OH radicals, optimizing the photocatalytic performance. As the atomic proportion of CN/BWO was 9:20, it exhibits a degradation degree of 90.2 % for rhodamine B (RhB) after 60 min illumination, significantly higher than pure BWO (44.0 %). Repetitive experiment results demonstrated the sample's good stability. Additionally, based on electrochemical tests and active species experiment results, the photocatalytic mechanism of the CN/BWO Z-scheme semiconductor structure involving photogenerated charge separation, migration, and photocatalysis was proposed.