Investigation and characterization of ZnO/CdS nanocomposites using chemical precipitation method for gas sensing applications

Zinc oxide/Cadmium sulphide (ZnO/CdS) nanocomposites were synthesized using the chemical precipitation method. One sample was annealed at 573 K and another one considered as-synthesized. Samples were characterized using UV–Vis spectrophotometer (UV–Vis), X-ray diffractometer (XRD), photoluminscence (PL), particles analyzer, scanning electron microscope (SEM) and transmission electron microscope (TEM). The XRD pattern represent the nanocomposites having hexagonal and cubic structure with an average crystallite size of 20.7–22.2 nm. The particle size of the nanocomposite annealed at 573 K was found to be increased slightly as compared with that of the as-prepared sample. The UV–Vis spectra revealed the drastic reduction of band gap of annealed sample. The SEM and TEM images of nanocomposites exhibited the formation, morphology and structure of the particles. The electrochemical impedance study demonstrated the low charge transfer resistance of annealed sample. In addition, the PL spectra of the nanocomposites exhibited green emission band. The oxygen gas was suitably tailored to verify the sensor response over the concentration range of 50–250 ppm at room temperature. The observed results reveal that the performance, response and recovery time of ZnO/CdS nanocomposite annealed at 573 K is found be increased.