Humidity sensing properties of mesoporous iron oxide/silica composite prepared via hydrothermal process

Mesoporous Fe2O3/SiO2 composites with various Fe/Si molar ratios were synthesized via hydrothermal route and then studied as humidity sensor materials. The best result is obtained for the sample with a Fe/Si molar ratio of 0.5, which exhibits high humidity sensitivity, rapid response and recovery, small hysteresis and excellent linearity. The impedance of the sensor varies more than four orders of magnitude during the whole relative humidity (RH) from 11 to 95%. The response time and recovery time of the sensor is about 20 and 40 s, respectively. These results make our product a good candidate in fabricating high performance humidity sensors.