Biotemplate fabrication of SnO2 nanotubular materials by a sonochemical method for gas sensors

A sonochemical method is developed to fabricate SnO2 nanotubular materials from biological substances (here, it is cotton). The cotton fibers in SnCl2 solution were first treated with ultrasonic waves in air, followed by calcinations to give nanotubular materials that faithfully retain the initial cotton morphology. The microstructure and morphology of the obtained SnO2 nanotubules were characterized by the combination of field-emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and N-2 adsorption/desorption measurements. The thermal behavior and crystalline properties were examined in the temperature range of 450-700 A degrees C. The nanocrystals composing of SnO2 nanotubules were estimated about 8.5, 13.2, and 14.2 nm corresponding to calcination temperatures of 450, 550, and 700 A degrees C, respectively. The sensor performance of biomorphic SnO2 nanotubules calcined at 700 A degrees C was investigated in the atmosphere of ethanol, formaldehyde, carbinol, carbon monoxide, hydrogen, ammonia, and acetone, respectively, which exhibited a good selectivity for acetone at a working temperature of 350 A degrees C. The sensitivity to 20 ppm acetone, S, was 6.4 at 350 A degrees C with rapid response and recovery (around 10-9 s). These behaviors were well explained in relation to the morphology of the nanotubules thus produced.