Photocatalytic Decomposition of O-ethyl S-[2-diisopropylaminoethyl] methylphosphonothioate, VX, Molecule on Titanium Dioxide in Ambient Condition using ATR-FTIR Spectroscopy

Abstract

Abstract The adsorption structure and photocatalytic decomposition of nerve agent, O-ethyl S-[2-diisopropylaminoethyl] methylphosphonothionate (VX) on powdery TiO2 film experimentally studied by using in-situ attenuated total reflection - infrared Fourier transform spectroscopy (ATR-FTIR) at ambient condition. Characteristic IR frequency of VX molecules adsorbed at the surface of TiO2 was observed. The results showed that VX molecule at the surface of TiO2 was immediately oxidized to ethyl methylphosphonic acid (EMPA) and diisopropylaminoethanthiol (DESH) by the P-S cleavage. C-N cleavage by the photocatalysis was also observed simultaneously with appearance of the characteristic IR frequencies as secondary amin species. The oxidation of an aliphatic function group of VX molecule was then accompanied by the decomposition of the skeletal structure as P-S and C-N of VX. Rarely EA2192 production by the TiO2 photocatalysis has experimentally verified by this ATR-FTIR analysis. The plausible adsorption structure and the photocatalytic reaction mechanism of VX at the surface of the TiO2 photocatalyst are also elucidated.