Embed CdS into MIL-101 to Boost the Photocatalytic Activity for Methylene Blue and Methyl Orange Degradation in the Visible Range

This research presents the hydrothermal synthesis of the metal–organic framework MIL-101 (Cr) and the CdS/MIL-101 (Cr) catalyst in the photocatalytic degradation of Methylene Blue (MB) and Methyl Orange (MO) dye. The obtained MIL-101 with high crystallinity, a high specific surface area of 2,980m 2 /g and thermal stability up to 350 °C was synthesized by the hydrothermal method using an optimum ratio of Cr/HF = 1/1. The CdS nanoparticles with an average particle size of 10 nm are well embedded on the surface of the MIL-101 material, which decrease the MIL-101 band gap (Cr) from 3.42 eV to 2.26 eV, hence boosting the photocatalytic activity for the degradation of MB and MO in the visible range. The results demonstrated that CdS/MIL-101 was a good heterogeneous photocatalyst for the degradation of MB and MO. The reactive species of ·OH, e–, and h + generated on CdS were verified to play the predominant role and were believed to be the mechanism of photocatalysis. Using the initial rate approach and the Langmuir–Hinshelwood model, the team investigated the kinetics of the photocatalytic degradation reaction. The CdS/MIL-101 photocatalyst had very good catalytic recyclability and stability, which makes it a possible catalyst for cleaning organic pollutants in water.