Preparation of CdS nanoparticle by sol-gel method as low temperature NO₂ sensor

Nitrogen dioxide (NO₂) is important to be detected because it is toxic and harmful, even in very low concentration. However, most of the NO₂ gas sensors based on CdS, lack high sensitivity and operate at high temperatures. Thin film based NO₂ gas sensor of Cadmium sulphide (CdS) nanostructures were prepared by the chemical route and deposited over the Pt Inter Digital Electrodes (IDEs) substrates. Thin film of CdS were there annealed at 500°C with different spin coating speed (1000, 2000 and 3000 rpm) using spin coating technique. The CdS thin film was characterized by different techniques, such as X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared spectroscopy (FT-IR) and Ultraviolet– Visible spectroscopy (UV–Vis), which offered the information about the chemical structure of CdS, whereas electron microscopy images provided information regarding the morphology of the thin film material. SEM observation showed that the prepared CdS nanoparticles were uniformly dispersed and highly stabilized throughout the macromolecular chain that formed a uniform. CdS thin film observed maximum response (1.73×10²) at 70 °C operating temperature towards 20 ppm NO₂ gas. (author)