Comparative study on photocatalytic degradation of Congo red using different clay mineral/CdS nanocomposites

Clay mineral/CdS nanocomposites were successfully prepared via hydrothermal technique in the presence of different clay minerals for photocatalytic degradation of Congo red. The relevant structures and properties were systematically characterized and studied, including phase composition, crystal size, color, optical property and morphology of the obtained nanocomposites. The generated hexagonal CdS nanoparticles with a diameter of 30–60 nm were well anchored on the surface of clay minerals. Interestingly, the types of clay minerals affected the UV–Vis absorbance and band-gap energy of clay mineral/CdS nanocomposites, and the clay mineral/CdS nanocomposites derived from one-dimensional halloysite, sepiolite, and palygorskite exhibited higher photocatalytic activity for Congo red degradation than that of two-dimensional lamellar kaolin and montmorillonite. In addition, incorporating of clay minerals not only effectively decreased the size of CdS nanoparticles without the obvious aggregation, but also guard against electrochemical corrosion of CdS during photocatalytic degradation.