Barium titanate perovskite nanoparticles as a photoreactive medium for chemical warfare agent detoxification

Barium titanate nanoparticles (BTO-NPs) in the size range 8-12 nm, prepared by gel collection, are found to be a photoreactive detoxifier for Chemical Warfare Agent vapors, specifically, the sulfur mustard surrogate (2-chloroethyl ethyl sulfide). The relatively monodisperse, uniformly spherical BTO-NPs, initially dispersed in alcohol solvents, form a stable and porous aggregated structure reminiscent of a nanostructured material with voids/pores of an average diameter of 4.6 nm and a relatively narrow distribution of their sizes (2.5-8.7 nm). Due to the interparticle porosity and a polar, chemically active surface, signifcant amounts of CWA surrogate and its decomposition products were adsorbed on the BTO-NPs. The recorded weight uptake on the perovskite was the highest among a series of materials and nanocomposites known for their detoxification activity and tested at the same conditions (169 mg/g, compared to 117 mg/g for zinc oxide and <100 mg/g for other transition metal oxides). Besides adsorption, BTO nanomaterial acts simultaneously as an efficient heterogeneous catalyst by degrading the toxic vapors to alcohols, sulfides and thiols - molecules of significantly lower toxicity than the CWA surrogate. Hydrolysis and dehydrohalogenation were the predominant detoxification pathways, via the formation of the intermediate cyclic sulfonium, whether under light or in the dark. Ambient light irradiation promoted the photo-oxidation and photo-degradation by radical intermediates formed. With an unhindered oxygen rich surface, underlying highly polarizable lattice structure, and large accessible surface area, barium titanate nanoparticles are investigated as a potentially useful medium for photoreactive detoxification of chemical warfare agent vapors.