Influence of temperature conditions of forming nanosized SnO2-based materials on hydrogen sensor properties

Abstract

Semiconductor sensors are widely used to detect toxic and flammable gases, and nanosized SnO2 is usually applied as material for gas-sensitive layers of the sensors. Sensor nanomaterial has to provide appropriate value of the electrical resistance of the sensor in air and high sensor response to analyzed gas. Sol–gel synthesis is the most promising to obtain SnO2 nanomaterial because it enables to rich high chemical homogeneity of the obtaining material, to control its particle size and structure at different stages of the material synthesis. These characteristics of the nanomaterials have to determine the sensor properties. To obtain SnO2 sensor nanomaterial, synthesis of xerogel by a sol–gel method via SnCl4·5H2O dissolved in the ethylene glycol was carried out. To provide optimal values of the sensor electrical resistance in air, decomposition of the xerogel was studied by DTA–DTG analysis. This study was carried out by heating the xerogel to 1000 °C in air with heating rates of 2.5, 5 and 10 °C min−1. It was found that decomposition of the xerogel was performed in several stages: water desorption, removing ethanediol-1,2, HCl and CO2. Using the selected heating mode with isothermal holding at 280, 350, 390 and 600 °C, optimized SnO2 nanomaterial was obtained. It was found that sensors based on this material had suitable values of their electrical resistances (150–400 kΩ) and possessed high responses to very small concentration of hydrogen.