Nanoarchitectronics for Photocatalytic CO₂ Reduction: Unveiling Interfacial Charge Transfer Excitons in the KFeO₂–BiVO₄ Composite

In this study, a series of KFeO2–BiVO4 nanocomposites with different KFeO2 contents have been prepared by a simple hydrothermal method and used as photocatalyst in the photocatalytic reduction of CO2 with H2O to methane (CH4) and carbon monoxide (CO) under visible light irradiation. The as-synthesized KFeO2–BiVO4 nanocomposites have been characterized using an X-ray diffractometer (XRD), a scanning electron microscope (SEM), an attenuated total reflection Fourier transform infrared spectrometer (ATR-FTIR), an ultraviolet–visible light spectrometer (UV–vis), and a photoluminescence spectrometer (PL). In the photocatalytic CO2 reduction experiments, KFeO2–BiVO4 (1:1) exhibited an improvement of photocatalytic activity for the CO2 photoreduction due to the reduced electron–hole pair recombination and increased BET specific area. When irradiated with a blue light lamp, the cumulative CO yield for KFeO2–BiVO4 (1:1) reached about 54.6 μmol g–1 (the quantum yield was 0.14%) and the cumulative yield of CH4 was 34.1 (the quantum yield was 0.35%). Based on the experimental results, a plausible photocatalytic reaction mechanism for photoreduction of CO2 has been proposed in this study. In addition, the charge enhancement photoreduction properties of KFeO2–BiVO4 have been verified by DFT calculations