Scrolled titanate nanosheet composites with reduced graphite oxide for photocatalytic and adsorptive removal of toxic vapors

Abstract

Nanocomposites (TiO-NTbs/rGO) consisting of titanate nanosheets (H2Ti3O7) scrolled to nanotubes (TiO-NTbs) and deposited on reduced graphite oxide (rGO) were synthesized through the combination of low-power/low-frequency (37 kHz) ultrasound and hydrothermal treatment procedures. The materials were characterized by X-ray diffraction, high-resolution transmission electron microscopy, N2 physisorption, thermal analysis (in air or helium), potentiometric titration, X-ray photoelectron spectroscopy, and diffuse reflectance spectroscopy. The addition of 4% rGO led to an optimal surface area of the composite (359 m2/g). The materials, when tested as media to remove toxic vapors of a chemical warfare agent (mustard gas) surrogate either under dark or visible light conditions, exhibited an adsorption capacity greater than 600 mg/g, which i was higher than those of other well-preforming materials (e.g., barium titanate nanoparticles or metal?organic frameworks). The photocatalytic activity of TiO-NTbs was also superior to that of P25 or other well-known nanomaterials. On their surface, various compounds of low- or non-toxicity were identified to be formed photochemically via free radical reactions.