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 degrees 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 less than or similar to 3 nm. These films were tested for sensing H-2 concentration of 0.1-1000 ppm at optimized operating temperature of 265 degrees C. The results showed that sensitivity (R-air/R-gas 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 H-2, give high sensitivity (200 x 10(-3)/ppm) for lowest concentration (0.1-1 ppm) of H-2. The selectivity for H-2 against relative humidity (RH), CO2, CO and LPG gases is also good. The sensor, at operating temperature of 200 degrees C, is showing nearly zero response to 300 ppm of H-2, 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 H-2 sensor at an operating temperature of 265 degrees C, and as an acetone sensor at the operating temperature of 200 degrees C. (C) 2010 Elsevier B.V. All rights reserved.