Facile fabrication, characterization and efficient photocatalytic activity of surfactant free ZnS, CdS and CuS nanoparticles

In this research, some metal sulfide nanoparticles (NPs) including ZnS, CdS and CuS NPs were prepared by a simple and low-cost co-precipitation method for the photocatalytic degradation of Bromothymol blue dye (BTB) under natural sunlight irradiation. The synthesized materials were characterized by XRD, FT-IR, UV-vis DRS, PL, TGA, SEM and TEM techniques for the investigation of structural, electronic, thermal, and morphological properties. The optical absorption and the band gaps of the ZnS, CdS, and CuS NPs were calculated as 3.62 eV, 2.21 eV, and 1.16 eV from the UV-vis DRS. XRD results demonstrate the cubic structure of ZnS NPs, CdS NPs, and the hexagonal structure of CuS NPs in the polycrystalline nature. The spherical shape and size of the NPs are observed in the range of 5–12 nm from the XRD and TEM analysis. The FTIR spectra reveal that the functional groups are associated with the synthesized materials by the metal-sulfur (Zn-S, Cd-S, and Cu-S) vibration bands. The CdS NPs exhibited a more efficient photocatalytic activity for the BTB dye degradation than the ZnS and CuS NPs. Similarly, the results on the photostability for the degradation of BTB indicate that the CdS NPs exhibited the activity and stability for up to 5 cycles which are better than those of the ZnS and CuS NPs, consistent with their tiny size and extremely effective reacting surface area. Hence, the semiconducting materials are expected to have the potential as a highly efficient, cost-effective and eco-friendly heterogeneous catalyst for industrial applications.