Visible-light-driven photocatalysts for hydrogen production by water splitting

Two photocatalysts, namely, graphene oxide and TiO2/CdS/CNT nanocomposite for hydrogen production from pure water and seawater were synthesized by modified Hummer’s method and sol-gel method, respectively. The photocatalysts were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive Spectroscope (EDS) and UV-Visible Diffuse Reflectance Spectroscope (UV-DRS). The particle size of graphene oxide and TiO2/CdS/CNT nanocomposite was measured to be 14.84 nm and 9.03 nm, respectively. The photocatalytic activity on hydrogen generation from pure water and seawater was investigated under visible-light irradiation (λ ≥ 420 nm) at room temperature. It was observed that TiO2/CdS/CNT nanocomposite showed higher photocatalytic H2 production rate (3502 µmol/h from pure water and 1373 µmol/h from seawater) than graphene oxide (2548 µmol/h from pure water and 995 µmol/h from seawater). The experimental results indicate that the improved photoactivity of TiO2/CdS/CNT nanocomposite is due to the presence of MWCNTs which enhances hydrogen production, improves the photo-stability of CdS and retards the recombination rate of electron-hole pairs. The present study reveals that the photocatalytic activity of ternary nanocomposite is superior to graphene oxide. Thus, the novel photocatalyst TiO2/CdS/CNT nanocomposite holds high stability and photo-activity and improves the quantity of hydrogen produced from 1 l of water. © 2019, © 2019 Taylor & Francis Group, LLC.