Reduced graphene oxide-TiO2 nanocomposite as a promising visible-light-active photocatalyst for the conversion of carbon dioxide

Photocatalytic reduction of carbon dioxide (CO2) into hydrocarbon fuels such as methane is an attractive strategy for simultaneously harvesting solar energy and capturing this major greenhouse gas. Incessant research interest has been devoted to preparing graphene-based semiconductor nanocomposites as photocatalysts for a variety of applications. In this work, reduced graphene oxide (rGO)-TiO2 hybrid nanocrystals were fabricated through a novel and simple solvothermal synthetic route. Anatase TiO2 particles with an average diameter of 12 nm were uniformly dispersed on the rGO sheet. Slow hydrolysis reaction was successfully attained through the use of ethylene glycol and acetic acid mixed solvents coupled with an additional cooling step. The prepared rGO-TiO2 nanocomposites exhibited superior photocatalytic activity (0.135 μmol gcat-1 h-1) in the reduction of CO2 over graphite oxide and pure anatase. The intimate contact between TiO2 and rGO was proposed to accelerate the transfer of photogenerated electrons on TiO2 to rGO, leading to an effective charge anti-recombination and thus enhancing the photocatalytic activity. Furthermore, our photocatalysts were found to be active even under the irradiation of low-power energy-saving light bulbs, which renders the entire process economically and practically feasible.