Ultrasound-activated TiO2/GO-based bifunctional photoreactive adsorbents for detoxification of chemical warfare agent surrogate vapors

Abstract

Commercial TiO2 (P25), alone or in the presence of graphite oxide (GO), was exposed to ultrasound treatment (US) with the objective to modify the surface of nanoparticles through introducing defects and chemical heterogeneity, and to build the composite with GO of synergistic features. The obtained materials were extensively characterized using XRD, HR-TEM, TA-MS, FTIR, XPS, potentiometric titration, adsorption of nitrogen, and UV/Vis diffuse reflectance techniques. The results showed that the US treatment/activation led to the formation of defects on the surface of the TiO2 nanoparticles, which were associated with an increase in the amount of terminal hydroxy groups, and which resulted in narrowing of the band gap energy. The composite formed upon the ultrasonic activation contained partially reduced GO particles deposited on the surface of TiO2 aggregates and bonded with the titania phase through its carboxylic groups existing at the edges of small defectous graphene particles, leading to a high volume of mesopores formed between the particles/aggregates of the nanoparticles. The US-treated materials showed a superior bifunctional detoxification performance, to adsorb and photocatalytically decompose vapors of a chemical warfare agent surrogate, as a result of the surface alteration/activation and an increase in the porosity.