CdS Microspheres Composed of Nanocrystals and Their Photocatalytic Activity

A simple and template-free solution phase synthesis method has been developed for the preparation of novel CdS hollow microspheres using cadmium nitrate and thioacetamide precursors. This study investigates how process parameters—such as reaction time, precursor ratio, and reaction temperature—strongly influence the morphology of the final product. The synthesized products were characterized using a variety of techniques including X-ray powder diffraction (XRD), Raman spectroscopy, high-resolution scanning electron microscopy (HR-SEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray diffraction (EDX) analysis, X-ray photoelectron spectroscopy (XPS), and UV-visible diffused reflectance spectroscopy (UV-DRS). XRD analysis confirmed the cubic structure of the CdS microspheres, further supported by Raman spectroscopy. HR-SEM measurements revealed the spherical morphology of the CdS microspheres, formed through the oriented aggregation of primary CdS nanocrystals. TEM measurements confirmed the hollow shell-like structure of the spheres, with their hollow interiors explained by the Ostwald ripening mechanism. UV-DRS studies indicated that the band gap of the CdS microspheres increased with higher cadmium-nitrate-to-thioacetamide ratios. Furthermore, the photocatalytic activity revealed that the synthesized CdS hollow microspheres exhibited excellent photocatalytic performance in rapidly degrading methyl tert-butyl ether.