Easy Synthesis of Ordered Mesoporous Carbon–Carbon Nanotube Nanocomposite as a Promising Support for CO<sub>2</sub> Photoreduction

An easy solid–liquid grinding hard-templating route was demonstrated for the preparation of an ordered mesoporous carbon–carbon nanotube (OMC–CNT) nanocomposite by using natural soybean oil as a carbon source, which is a kind of reproducible liquid seed fat derived from soybean. The as-prepared OMC–CNT nanocomposite has bimodal mesostructures with a relative large pore volume and high surface area which can potentially be used as support in real catalysis/photocatalysis. Indeed, we have demonstrated that such an OMC–CNT nanocomposite used as a support for g-C<sub>3</sub>N<sub>4</sub> catalyst exhibited an excellent photocatalytic performance in the reduction of CO<sub>2</sub> with H<sub>2</sub>O. The excellent photocatalytic activity of the g-C<sub>3</sub>N<sub>4</sub>/OMC–CNT catalyst can be ascribed to its unique structure of carbon support with numerous favorable properties such as interconnected and hierarchical mesostructure, large surface area, and high electronic conductivity, which contributes to the diffusion and mass transfer of reactants or products; meanwhile, the high electronic conductivity of the carbon nanotube will promote the separation and migration efficiency of photogenerated electron–hole pairs during the photocatalytic process.