Optoelectronic and antimicrobial activity of composite zinc oxide and cadmium sulphide quantum dots and application in water treatment

In the present study, we report the synthesis of composite zinc oxide and cadmium sulphide nanoparticles by a chemical route. ZnO–CdS nanocomposites have been gaining much importance as they show fascinating opto-electronic properties such as tunable band gap and the nanomaterials are suitable for fast photon absorption, transportation and collection. The prepared composite nanoparticles have been characterized by UV–VIS absorption, X-ray diffraction (XRD) and TEM, AFM and FTIR observation. UV-VIS optical spectroscopy study has been carried out to determine the band gap of the composite zinc oxide and cadmium sulphide thin film and it shows a blue shift with respect to the bulk value. The nanocomposites show enhanced opto -electronic properties compared to the individual constituents. The band gap of CdS–ZnO nanocomposites depend on various experimental parameters such as reaction time, concentrations of cadmium salt, and also chemical nature of the cadmium salt. The band gap value of the ZnO–CdS nanocrystalline films are obtained in the range of 3.88–4.14 eV which is higher than that of bulk value of ZnO (3.3 eV) and CdS (2.42 eV). The synthesized nanoparticles exhibited high antibacterial activity and can be used for water purification. (author)