LPG Gas Sensing Applications of SnO₂/ZnO Nanoparticles

Nanostructured SnO₂ and SnO₂/ZnO materials were synthesized by a sol–gel method. Cetyl-trimethyl ammonium bromide (CTAB) was used as capping reagent. X-ray diffraction pattern (XRD) and Scanning Electron Microscopy (SEM) were used to identify the sizes, shapes and phases of as synthesized samples. The average crystalline and grain size observed from XRD and SEM was confirmed in the nano range. Structural and Optical properties of as synthesized samples were studied by UV-Visible absorption spectrophotometer. Thick films of SnO₂ and SnO₂/ZnO were fabricated by a screen printing method and used in LPG gas sensing applications. The changes in the resistance of SnO₂ and SnO₂/ZnO thick films were characterized at 100 °C temperature with varying LPG concentration from 0 to 12000 ppm. The SnO₂/ZnO thick film was observed to be more sensitive to LPG as compare to pure SnO₂ thick film at 100 °C temperature. Pure SnO₂ thick film shows response of 29.6% to the 9000 ppm LPG gas concentration with response time 20 sec and recovery time 25 sec approximately, whereas SnO₂/ZnO thick film was exhibited response of 46% to the LPG gas concentration of 6000 ppm at 100 °C. The response and recovery time of the nanocomposites SnO₂/ZnO thick film sensor on exposure to 6000 ppm of LPG gas was 19 sec and 22 sec respectively.