Reactive adsorption and photodegradation of soman and dimethyl methylphosphonate on TiO2/nanodiamond composites

We report on the synthesis and characterization of TiO2/Nanodiamond (ND) nanocomposites for rapid decontamination of chemical warfare agents (CWA) and toxic industrial compounds prepared by a simple water-based, low-temperature method using urea as a homogeneous precipitating agent. The excellent water-compatibility of NDs promoted their good dispersion within the TiO2 matrix resulting in intergrown TiO2/ND nanostructures. NDs with an abundance of oxygen-containing surface moieties increased the porosity of the composites resulting in their three times more efficient spontaneous degradation of the CWA soman in solution compared to pure TiO2. In situ DRIFT spectroscopy revealed the enhanced reactive adsorption and solar light photodecomposition of dimethyl methyl phosphonate vapor on TiO2/ND. The charge transfer across TiO2/ND interfaces that hinder recombination of photo-excited electron-hole pairs was inferred from surface potential measurements. The results indicate that well-dispersed NDs forming heterojunctions together with their high porosity contribute to the reactive properties of the nanocomposites.