CQDs/BiOCl Photocatalysts for the Efficient Treatment of Congo Red Aqueous Solution under Visible Light

The surface of BiOCl nanosheets, prepared by a simple hydrothermal method, was decorated by carbon quantum dots (CQDs) through a microwave-assisted procedure. According to Diffuse Reflectance spectroscopy (DRS), light-harvesting properties improved significantly, which was explainable based on the bandgap of the final photocatalyst, 1.15 eV. Elemental analysis results coupled with scanning electron microscopy (SEM) images proved changes in the morphological characteristics after adding CQDs to the support; While in powder X-ray diffraction (XRD) patterns, there was no indication of further crystalline phases on the surface of BiOCl nanosheets. The photocatalytic performance of the nanostructures was evaluated by Congo red dye removal under visible light at room temperature. The photoreaction obeyed first-order kinetics with the rate constant of 0.011 min-1. According to the experiments, photodegradation was noticeably affected by catalyst dosage, dye concentration, and pH, which were all optimized. The photocatalytic performance of the prepared nanostructure was mechanistically discussed, considering the desirable role of CQDs towards reaching superior photoactivity.