Synthesis and gas sensing properties of hierarchical SnO2 nanostructures

A low-cost and environmentally friendly hydrothermal route to the synthesis of hierarchical SnO2 nanostructures was described. The structure and morphology of the as-prepared product were characterized by various characterization techniques. The results revealed that these nanostructures were built from two-dimensional (2 D) nanosheets with the thicknesses of about 8 nm. Moreover, the amount of hydrochloric acid played a crucial role in the control of the final size and morphology of product. Gas sensors based on hierarchical SnO2 nanostructures were fabricated, and their gas sensing properties were tested for response to ethanol, acetone, formaldehyde, CO, toluene, H2 and H2S gases. The sensor showed excellent selectivity toward ethanol. At an ethanol concentration of 100 ppm, the response of the hierarchical SnO2 nanosheets was about 33, which was about 2.5 times higher than that of the nanoparticles. The response time of the sensor to 60 ppm ethanol was shorter than 11 s at the optimal operating temperature of 275 °C. The enhancement in gas sensing properties was attributed to their unique structures.