Facile gamma radiolytic methodology for TiO₂-rGO synthesis: Effect on photo-catalytic H₂ evolution

TiO₂ (P25) decorated reduced graphene oxide (rGO) is synthesized by γ-radiolytic technique using water-ethanol solvent medium. Visible light absorption was confirmed by UV-Visible spectroscopy. Photoluminescence (PL) study revealed a decline in electron-hole recombination rate signalled by a sharp fall in luminescence of TiO₂. Under such scenario, electron transfer from TiO₂ conduction band to the conjugated sheet becomes a preferred pathway in the presence of rGO, which is further confirmed by photocurrent measurement. TiO₂ -rGO composite with 1 wt. % rGO was found to be the best composition in terms of visible light absorption, while retaining TiO₂ crystallinity. Transmission electron microscopy and Raman spectroscopic studies confirmed the coating of rGO sheet with TiO₂ nanoparticles. TiO₂ -rGO was found to show about 150 times higher photocatalytic H₂ generation under 250 W UV-Visible light irradiation than pristine TiO₂. In addition to this, TiO₂ -rGO composite shows hydrogen production yield of 35 μmol/h.g under visible light (λ = 400 nm) irradiation. Thus γ-radiolysis can be considered to be a viable technique, which helps in synthesizing photocatalytically active nanocomposite with high H₂ evolution rate. In the light of these interesting aspects, a detail investigation is carried out to study the effect of rGO concentration and illumination time on photocatalytic yield.