Surface Dual Metal Occupations in Fe-Doped FeBi_2-O₃ Induce Highly Efficient Photocatalytic CO₂ Reduction

CO₂ possesses extraordinary thermodynamic stability, and its reduction reaction involves multiple electron-transfer processes. Thus, high-density electron occupation on a catalyst surface is an effective driving force for improving the photocatalytic activity. Here, we report on the fabrication of Fe-doped Bi₂O₃ catalysts (denoted as FeBi_2-O₃) with different Fe contents using the solvothermal method. The self-assembled catalyst has a nanoflower-like morphology, and its performance of CO₂ reduction to CO is improved largely dependent on the Fe content. In the sample with a 7.0% Fe content (Fe_0.07Bi_1.93O₃), the CO evolution rate reaches 30.06 μmol g^-1 h^-1, which is about 6 times higher than the 4.95 μmol g^-1 h^-1 of pristine Bi₂O₃, and shows excellent photostability after three cycles, with each cycle lasting for 7 h. Theoretical calculation and spectral characterization reveal that such a good CO₂ reduction reaction performance arises from effective surface occupation of Fe, which not only enhances sunlight absorption but also significantly increases the surface electron density on the double metal active sites. This work provides a new strategy for improving the photocatalytic performance by surface metal doping in some metal oxide photocatalysts.