Influence of Reaction Time on the Size of SnO2 Nanospheres and Its Sensing Properties to VOC Gases

Abstract

Tin Oxide (SnO2) nanoparticles were synthesized using a simple hydrothermal technique at 100ºC reaction temperature in a Teflon lined autoclave without adding any surfactant. A systematic study has been conducted by varying the reaction time between 6 and 72 hours using Tin (II) Chloride hydrate as an inorganic precursor. The influence of reaction time on the morphology, distribution and crystallite size of SnO2 nanoparticles were analysed by transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The microscopy studies showed that the morphology of SnO2 nanoparticles are spherical and SnO2 nanospheres have an average size of 21.7-34.4 nm at different reaction times. The best combination of size and morphology was obtained at 21.7 nm at 12 hours reaction time. The gas sensing properties of SnO2 nanospheres to the vapors of various Volatile Organic Compounds (VOC), such as Ammonia, Ethanol, Methanol, Acetone, Chloroform and Toluene were also investigated by two probe resistivity unit in a closed vessel at room temperature. The response of SnO2 nanospheres to Ammonia vapor at different concentrations (1000-5000 ppm) was measured and SnO2 nanospheres are observed to have a good sensitivity (98%). These results indicate that SnO2 nanospheres exhibit to be an important alternative material for the detection of ammonia present in the environment at room temperature.