Visible light driven oxidation of harmful 2-Chloroethyl ethyl sulfide using SiO2-TiO2 composite particles and air

Abstract

Materials for remediation of toxic chemicals released in the environment are necessary. The current study provides a demonstration of visible light driven aerobic oxidation of 2-chloroethyl ethyl sulfide (2-CEES, sulfur mustard (HD) simulant) using rationally designed hybrid nanostructures composed of 5 nm TiO2 nanoparticles or TiO2 nanosheets supported onto monodispersed SiO2 Stöber spheres. Visible excitation (λ > 400 nm) resulted in oxidation of the thioether sulfur of 2-CEES. The highest reaction rate of 56.2 μmol/g/h (quantum yield (QY) of 1.64 × 10−5 molecules/photon) was obtained for the SiO2-TiO2 5 nm composite vs. 16.5 μmol/g/h (1.20 × 10−5 molecules/photon) for the SiO2-TiO2 nanosheets. Neat TiO2 nanoparticles and nanosheets displayed lower photocatalytic reactivity with reaction rates of 8.1 µmol/g/h (QY of 1.77 × 10−5 molecules/photon) and 5.1 µmol/g/h (1.20 × 10−5 molecules/photon), respectively. The reactivity of TiO2 nanostructures is due to surface defects/states. SiO2 support promotes the homogenous distribution of TiO2 nanoparticles allowing most of the active surface to remain available.