Wood-based carbon quantum dots for enhanced photocatalysis of MIL-88B (Fe)

To improve the Fenton-like photodegradation efficiency of MIL-88B(Fe) in visible light, carbon quantum dots (CQDs) were prepared from poplar wood powder as a raw material and added to a precursor solution of MIL-88B (Fe) to prepare CQDs@MIL-88B(Fe) materials using hydrothermal method. CQDs@MIL-88B(Fe) were characterized by X-ray powder diffraction (XRD), Brunner Emmett Teller (BET), Fourier transform infrared spectroscopy (FT-IR), Ultraviolet visible light spectrophotometry (UV-vis), X-ray photoelectron spectroscopy (XPS), photoluminescence spectra (PL), and photocurrent test. In this study, methylene blue (MB) was used as the target pollutant to test the catalytic performance of MIL-88B(Fe) and CQDs@MIL-88B(Fe), and the main free radicals involved in the reaction were determined by adding superoxide dismutase (SOD) and isopropanol (IPA) for comparative experiments. The experimental results show that because CQDs can be used as a photosensitizer and electron trapping agent, the light absorption capacity and photogenic carrier separation efficiency of CQDs@MIL-88B(Fe) were improved. Hence CQDs@MIL-88B(Fe) produced hydroxyl radicals more efficiently. Within 1 h, the degradation rate of MB by CQDs@MIL-88B(Fe) was about 99%. After five cycles of recycling, the degradation rate of MB by CQDs@MIL-88B(Fe) was still 92%. These results indicate that CQDs have good application potential in enhancing Fenton-like photodegradation.