Construction of novel type II heterojunction WO3/Bi2WO6 and Z-scheme heterojunction CdS/Bi2WO6 photocatalysts with significantly enhanced photocatalytic activity for the degradation of rhodamine B and reduction of Cr(VI)

As a novel photocatalyst with visible light responsiveness, Bi2WO6 has excellent activity in treating wastewater containing organic pollutants and noble metals. However, its photocatalytic action is limited due to the rapid recombination of photogenerated electrons and holes. Based on the study of Bi2WO6, a type Ⅱ heterojunction photocatalyst (WO3/Bi2WO6) and a Z-scheme heterojunction photocatalyst (CdS/Bi2WO6) were constructed. Composites exhibited higher catalytic activity than pure Bi2WO6. The degradation efficiency of RhB(50 mg/L) and reduction efficiency of Cr(VI) (50 mg/L) by 5%WO3/Bi2WO6 catalyst within 60 min of photocatalytic reaction was 98.82% and 53.82%, respectively. The degradation efficiency of RhB and reduction efficiency of Cr(VI) by 15%CdS/Bi2WO6 catalyst was 99.52% and 69.52%, respectively. By studying the structural composition, microscopic morphology, photoelectrochemical performance, and light absorption performance of the catalysts of the two different systems. These mechanisms may help to explain the reasons for the enhanced activity of the composite photocatalysts. In addition, mixed wastewater containing organic pollutants (RhB) and heavy metal ions (Cr(VI)) was used to simulate real and complex wastewater, which provided more ideas for wastewater treatment problems.