In the degradation reaction, a 300 W xenon lamp (MC-PF300, Beijing MerryChange) with an optical filter (>420 nm) was employed to provide the visible light. 50 mg of catalyst was added to the 50 mL indole solution (20 mg L−1) at room temperature. The mixture was stirred in darkness for 1 h to avoid the impact of adsorption on measurement results. Subsequently, the light irradiation was initiated. 0.5 mL of supernatant in the reactor was collected at regular intervals for the determination of indole concentration. A high-performance liquid chromatography workstation (HPLC, Agilent 1260 Infinity II) with a UV/visible detector was used to measure the concentration of indole. The measurement was performed on a C18 analytical column (5 μm), and the mobile-phase was made up of methanol and deionized water (80 : 20 v/v). The detection wavelength was 254 nm, and the column temperature was 30 °C. In the cyclic test, the catalyst is isolated through centrifugation at 8000 rpm and rinsed with deionized water, and reused under the same conditions.