Rational Design and Construction of a CdS QDs/InVO4 Atomic-Layer (110)/(110) Facet S-Scheme Heterojunction for Highly Efficient Photocatalytic Degradation of C2H4

Exploring high efficiency S-scheme heterojunction photocatalysts with strong redox ability for removing volatile organic compounds from the air is of great interest and importance. However, how to predict and regulate the transport of photogenerated carriers in heterojunctions is a great challenge. Here, density functional theory calculations were first used to successfully predict the formation of a CdS quantum dots/InVO4 atomic-layer (110)/(110) facet S-scheme heterojunction. Subsequently, a CdS quantum dots/InVO4 atomic-layer was synthesized by in-situ loading of CdS quantum dots with (110) facets onto the (110) facets of InVO4 atomic-layer. As a result of the deliberately constructed built-in electric field between the adjoining facets, we obtain a remarkably enhanced photocatalytic degradation rate for ethylene. This rate is 13.8 times that of pure CdS and 13.2 times that of pure InVO4. In-situ irradiated X-ray photoelectron spectroscopy, photoluminescence and time-resolved photoluminescence measurements were carried out. These experiments validate that the built-in electric field enhanced the dissociation of photoexcited excitons and the separation of free charge carriers, and results in the formation of S-scheme charge transfer pathways. The reaction mechanism of the photocatalytic C2H4 oxidation is investigated by in-situ electron paramagnetic resonance. This work provides a mechanistic insight into the construction and optimization of semiconductor heterojunction photocatalysts for application to environmental remediation.