Co3O4 Nanocrystals Coupled with Co-Doped TiO2 Nanobelts as a Synergistic Photocatalyst for Efficient Photoconversion of CO2 and H2O to Solar Fuels

Semiconductor-based photocatalytic technology for CO2 reduction to produce fuels is a key toward developing new sustainable energy sources, but this technology remains a huge challenge. Herein, a p–n heterojunction photocatalyst composed of Co-doped TiO2 nanobelts (Co–TiO2 NBs) coupled with Co3O4 nanoparticles (NPs) is designed through a two-step operation of hydrothermal ion exchange and medium temperature calcination. Characterization of the product demonstrates that Co3O4 NPs are intimately embedded on the surface of Co–TiO2 NBs, and they provide an ideal heterointerface with strong electron interaction. As compared to the single-phase TiO2 NBs and Co3O4 NPs, the Co3O4/Co–TiO2 nanocomposite exhibits significantly improved photocatalytic performance for the conversion of CO2 to H2O under simulated solar irradiation. It is shown that the p–n junctions constructed by p-type Co3O4 NPs and n-type Co–TiO2 NBs can effectively promote the transfer of photogenerated charges at the interface and improve the adsorption of CO2 molecules, thus leading to a remarkable enhancement in photocatalytic CO2 reduction activity.