Adsorption and Decomposition of Sarin Simulant DIMP on Reduced and Oxidized TiO ₂ and Pt/TiO ₂

To develop enhanced catalytically active materials for use in protection against toxic chemical exposures, such as chemical warfare agents (CWAs), there needs to be a fundamental understanding of the driving factors for agent decomposition. Within this study, we used in situ infrared absorbance spectroscopy to investigate the role of sample pretreatment in modifying the surfaces of TiO2 and 1% Pt/TiO2 and the subsequent decomposition of the nerve agent simulant diisopropyl methylphosphonate (DIMP). Surface and subsurface defects were generated in both TiO2 and 1% Pt/TiO2 when pretreated in a reducing environment. These defects served as sites for the decomposition of DIMP into acetone, mesityl oxide, and isopropyl alcohol (IPA). Due to the increased defect density on the surface resulting from a strong metal–surface interaction, reduced 1% Pt/TiO2 showed increased DIMP decomposition compared to that of reduced TiO2. Pretreatment of the materials in an oxidizing environment resulted in both TiO2 and 1% Pt/TiO2 having a lower defect density compared with the reduced samples. However, for the oxidized 1% Pt/TiO2, surface-accessible active oxygen species were produced, leading to a more selective degradation of DIMP. This study provides an understanding of the impact of different pretreatments of titania, with and without surface-supported Pt, on DIMP decomposition. This includes capturing the roles defects or active oxygen species formed during pretreatment play in DIMP surface reactivity. These insights will assist in the development of next-generation CWA protection or decontamination materials.