The controlled synthesis and DFT investigation of novel (0D)–(3D) ZnS/SiO2 heterostructures for photocatalytic applications

Abstract

A ZnS/SiO₂ photocatalyst was synthesized using a low-cost sol–gel wet chemical procedure. The as-synthesized ZnS/SiO₂ nanocomposites with different molar ratios exhibited superior performance in the photodegradation of two organic dyes under UV irradiation, with complete degradation of both dyes after 2 hours of exposure to UV irradiation. The photocatalyst structure, microstructure, and surface area were studied using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), and nitrogen adsorption (S_BET) studies. The results demonstrate that the ZnS/SiO₂ photocatalyst with 15% ZnS content has a bandgap energy similar to that of ZnS alone with a higher surface area of approximately 150 m² g⁻¹, which effectively increases the number of active sites and improves the photocatalytic activity of the prepared material. The measured bandgap energies were compared with the theoretical values obtained using the density functional theory (DFT) method, and the values were found to be very similar, with a low error percentage. In the case of a high ZnS content (greater than 15%), active site blocking occurred, and the removal rate dropped below 50%. The obtained results indicate that the photocatalytic data are in good agreement with the experimental characterization results for the prepared materials, including the BET and XRD results, confirming a close association between the photocatalytic activity and the surface area of the fabricated photocatalyst.