Theoretical and experimental study on gap calculation of binary ZnS-CdS nanocomposites and expected best photocatalysts

In the project, ZnS-CdS nanocomposite was prepared using a hydrothermal method to investigate their photocatalytic activity. The results of the X-ray diffraction (XRD) showed the hexagonal phase for cadmium sulfide and zinc sulfide which are synthesized as nanocomposites and the results of the scanning electron spectroscopy (SEM) indicated that the size of the nanoparticles decreases after the addition of ZnS to the structure of cadmium sulfide. By increasing the percentage of zinc, the size of nanoparticles decreased, which is a sign of improved photocatalytic activity. The calculated band gap by absorption coefficient and UV-visible spectroscopy measured was 2.7 eV for CdS, which has decreased by adding the Zn. The photocatalytic activity of prepared nanocomposites was studied by photodegradation of Rhodamine B (RhB) organic dye, and the sample with 0.1 M of zinc with a smaller gap and small size has been remarkably successful. In the next step, cadmium sulfide nanoparticles with different percentages of zinc were simulated and their band gaps were calculated by Density Functional Theory. The results have shown that the M05 calculation method was closer to the experimental results than other methods and the sample with 10% zinc can be a better photocatalytic material.