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, WO 2 chemisorbs and activates oxygen and functions as a potential cocatalyst for improving the utilization of charge carriers. Here, we report a WO 2 /SnS 2 composite photocatalyst with SnS 2 nanosheets vertically growing out of WO 2 nanofibers. In situ X-ray photoelectron spectroscopy and density functional theory calculations suggest the electron transfer from WO 2 to SnS 2, creating an internal electric field (IEF) at the interfaces with a direction pointing from WO 2 to SnS 2 . The IEF promotes spatial charge separation by driving photogenerated electrons in SnS 2 to move to WO 2, while photogenerated holes remain immobile. WO 2 shows a strong affinity for oxygen-containing species and chemisorbs O 2 and H 2 O molecules in a dissociative way, significantly reducing the kinetic barriers for the production of reactive oxygen species ( • OH and • O 2 – ). Under visible light irradiation, the WS30 nanofibers exhibit enhanced photocatalytic degradation of HCHO and CH 3 COCH 3, 4.8 and 7.2 times greater than that of pristine SnS 2, 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.