Abstract: The degradation of organic pollutants using semiconductor photocatalysts is a new ecological approach, but the currently available photocatalysts are not very efficient. Herein, in order to obtain efficient visible-light photocatalysts, g-C₃N₄/β-FeOOH-modified carbon quantum dots (CDs) composite photocatalysts with Z-Scheme charge transfer mechanism were successfully synthesized. The phase composition and morphology of the composite were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectrophotometry (FT-IR), and X-ray photoelectron spectroscopy (XPS) techniques. Due to the upconversion effect of the CDs, the optical response range of the composite was effectively widened, and the optical utilization rate was improved. The Z-Scheme heterostructure not only improves the light trapping ability, significantly inhibits charge-carrier complexation, and realizes the spatial separation of redox sites, but also ensures that the photocatalyst maintains a suitable valence-conductivity band position and maintains the strong redox reactivity. In addition, CDs have the unique characteristics of electronic storage and transfer, which effectively enhance the quantum separation efficiency of the composite. The photocatalytic efficiency was measured by degrading rhodamine B (RhB) under visible light. The degradation performance was the best when the weight ratio of CDs was 6%, and the RhB solution degradation rate reached 100 % in 60 min. The unique structure and reliable mechanism provide a way for the development of advanced photocatalyst.

Key words: Photocatalyst, Degradation, Visible light, g-C₃N₄, Carbon quantum dots