Photocatalytic Degradation of Volatile Organic Compounds over WO2/SnS2 Nanofibers.

Solar-powered volatile organic compound oxidation attracts interest, but its efficiency suffers from poor utilization of photogenerated electrons. Oxygen can capture the electrons and convert them into superoxide radicals upon being activated. As a unique oxygen-deficiency oxide, WO₂ chemisorbs and activates oxygen and functions as a potential cocatalyst for improving the utilization of charge carriers. Here, we report a WO₂/SnS₂ composite photocatalyst with SnS₂ nanosheets vertically growing out of WO₂ nanofibers. In situ X-ray photoelectron spectroscopy and density functional theory calculations suggest the electron transfer from WO₂ to SnS₂, creating an internal electric field (IEF) at the interfaces with a direction pointing from WO₂ to SnS₂. The IEF promotes spatial charge separation by driving photogenerated electrons in SnS₂ to move to WO₂, while photogenerated holes remain immobile. WO₂ shows a strong affinity for oxygen-containing species and chemisorbs O₂ and H₂O molecules in a dissociative way, significantly reducing the kinetic barriers for the production of reactive oxygen species (^•OH and ^•O₂^–). Under visible light irradiation, the WS30 nanofibers exhibit enhanced photocatalytic degradation of HCHO and CH₃COCH₃, 4.8 and 7.2 times greater than that of pristine SnS₂, respectively. The enhanced performance is attributed to the one-dimensional fibrous nanostructures, robust chemisorption of reactants, and IEF-driven charge separation. This work may inspire efforts to develop higher oxygen-affinity photocatalysts for photodegradation. [ABSTRACT FROM AUTHOR]