Hydrogen gas sensing based on nanocrystalline SnO2 thin films operating at low temperatures

Nanocrystalline (NC) SnO2 thin film has been prepared using sol-gel technique on Al2O3 substrates at low temperature. X-ray diffraction emerged that SnO2 thin film reveals the crystalline nature of NC SnO2 with a tetragonal rutile structure. Field emission scanning electron microscopy image emerged that the morphology of SnO2 thin film is uniform structure a polycrystalline. Hydrogen (H-2) gas sensing measurements were performed when the sensor exposed to very low H-2 concentration levels in the range 3-100 ppm at operating temperatures ranging from room temperature up to 125 degrees C. The NC SnO2 thin film sensor was found to be active for H-2 sensing, with high sensitivity (48%, 3 ppm and 180%, 100 ppm) respectively at room temperature. Moreover, the sensitivity of the sensor increased with increasing operating temperature, where the sensitivity value at 125 degrees C (902%, 3 ppm and 3475%, 100 ppm) of H-2 gas respectively. The obtained values were significantly higher as compared to the results in the literature. These findings attributed to increasing adsorption/desorption processes of gas molecules that lead to improving sensing properties of a gas sensor. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.