Design and fabrication of a CdS QDs/Bi2WO6 monolayer S-scheme heterojunction configuration for highly efficient photocatalytic degradation of trace ethylene in air

Abstract The S-scheme heterojunction with unique photogenerated electrons and holes migration pathway, excellent separation efficiency of photogenerated carrier and high redox potential, has great potential in this field of photocatalytic oxidation of atmospheric C2H4. However, optimising the transfer of photogenerated charge at the S-scheme heterostructure interface continues to a major challenge. Here, density functional theory (DFT) calculations were first conducted to predict an S-scheme heterojunction can be formed in the CdS quantum dots (QDs)/Bi2WO6 monolayer system, and then CdS QDs/Bi2WO6 monolayer S-scheme heterojunction were constructed by in-situ hydrothermal synthesis of CdS QDs onto Bi2WO6 monolayer. Bi-S bonds are deliberately introduced at the interface to maximise the photogenerated charge transfer. As expected, the substantial enhancement of the photocatalytic degradation of ethylene and the photostabilization of CdS is demonstrated. The S-scheme band alignment and the connected Bi-S coordination introduced at the junction interface allow highly efficient charge separation and an effective interfacial charge migration path. This research provides a basis for understanding the design of materials for the removal of hydrocarbons in air and environmental pollutant remediation, and improving the stability of sulfide and other photocatalysts to photocorrosion.