Nano particulate SnO2 based resistive films as a hydrogen and acetone vapour sensor

SnCl2 (solution) was spin coated on soda lime glass and Al2O3 substrate to obtain nano-particulate tin oxide film, directly by sintering at 550 °C for 40 minutes (min). The surface morphology and crystal structure of the tin oxide films were analyzed using atomic force microscopy (AFM) and X-ray diffraction (XRD). The size of SnO2 nanostructure was determined from UV–vis and found to be ≲3 nm. These films were tested for sensing H2 concentration of 0.1–1000 ppm at optimized operating temperature of 265 °C. The results showed that sensitivity (Rair/Rgas per ppm) goes on increasing with decreasing concentration of test gas, giving concentration dependent changes. Special studies carried out at low concentration levels (0.1–1 and 1–10 ppm) of H2, give high sensitivity (200 × 10−3/ppm) for lowest concentration (0.1–1 ppm) of H2. The selectivity for H2 against relative humidity (RH), CO2, CO and LPG gases is also good. The sensor, at operating temperature of 200 °C, is showing nearly zero response to 300 ppm of H2, and offering response to acetone vapour of 11 ppm. Selectivity for acetone against RH% and CO2 was also studied. These sensors can be used as H2 sensor at an operating temperature of 265 °C, and as an acetone sensor at the operating temperature of 200 °C.