Fe-TiO_2-x/TiO₂ S-scheme homojunction for efficient photocatalytic CO₂ reduction

CO₂-to-high value-added chemicals via a photocatalytic route is of interest but strangled by the low efficiency. Herein, a novel Fe-TiO_2-x/TiO₂ S-scheme homojunction was designed and constructed by using a facile surface modification approach whereby oxygen vacancy (OV) and Fe introducing on the TiO₂ nanorod surface. The as-synthesized Fe-TiO_2-x/TiO₂ S-scheme homojunction exhibits positive properties on promoting photocatalytic CO₂ reduction: i) the nanorod structure provides numerous active sites and a radical charge transfer path; ii) the doped Fe and OV not only synergistically enhance light utilization but also promote CO₂ adsorption; iii) the Fe-TiO_2-x/TiO₂ S-scheme homojunction benefits photoexcited charge separation and retains stronger redox capacity. Thanks to those good characters, the Fe-TiO_2-x/TiO₂ homojunction exhibits superior CO₂ reduction performances with optimized CO/CH₄ generation rates of 122/22 μmol g^-1h^-1 which exceed those of pure TiO₂ by more than 9.4/7.3 folds and most currently reported catalytic systems. This manuscript develops a facile and universal approach to synthesize well-defined homojunction and may inspire the construction of other more high-efficiency photocatalysts toward CO₂ reduction and beyond.