Carbon Coated TiO2 Photoanodes for All-vanadium Redox Photoelectrochemical Cells as Efficient Solar Energy Storage Device

An all-vanadium redox photoelectrochemical cell with a carbon coated TiO2 photoelectrode was designed to convert/store solar energy as a promising alternative to photogeneration of hydrogen. In this study, a facile high-temperature sintering approach was employed to tailor the thickness of the carbon coating at TiO2 photoanodes. Considerable enhancement in photocurrent has been observed using the carbon coated TiO2 photoanode in the all vanadium photoelectrochemical system when compared to the carbon-free counterpart. Particularly, the photoanode containing 2.07 wt% of carbon displayed 40% improvement in photocurrent compared to the one with bare TiO2 as the photoanode. It is proposed that the carbonaceous species created by high-temperature pyrolysis acted as a thin adsorption layer on the TiO2 for VO2+ to react with the photogenerated holes. Photocurrent enhancement of the carbon coated photoelectrodes is ascribed to a synergic effect between enhanced charge separation and high conductivity.