Tin oxide nanoparticles synthesized by gel combustion and their potential for gas detection

Tin oxide nanoparticles were synthesized starting from SnCl4·5H2O with the aid of polyacrylamide gel. The pyrolysis of the gel and the influence of the calcination temperature were discussed based on thermogravimetric analysis and X-ray powder diffraction. The decomposition of the polyacrylamide gel occurred mainly in the temperature range of 220-600 °C, after which resulting in a heap of fine powders. The average grain size of the nanoparticles synthesized at 600, 700 and 800 °C were calculated to be 8.1, 19.2 and 27.9 nm, respectively. The prepared SnO2 nanoparticles were sphere-like and uniform in size, weakly aggregated in thin platelets as indicated by scanning electron microscope (SEM) images. Thick-film sensor samples based on the as-synthesized SnO2 nanoparticles without specific additives showed response sensitivity of around 28.8 at the optimal detection temperature of 150 °C to 30 ppm H2S gas, while their responses to 1000 ppm of CO or CH4 were negligible.