Development of High Sensitivity Humidity Sensor Based on Gray TiO2/SrTiO3 Composite

A gray TiO2/SrTiO3 composite nanocrystalline sensor with narrow band-gap was successfully prepared through a facile wet chemical method. The precursor was calcined in N2 flow under atmospheric pressure and thereafter, a humidity sensor based on the composite was fabricated. The sensor showed high resistive sensitivity and varied by more than four orders of magnitude with an increase in relative humidity (RH) from 11% to 95%. The response and recovery time were about 3.1 s and 76 s, respectively with maximum hysteresis at 1% RH. In comparison with pure SrTiO3 and black TiO2, the gray composite based device exhibits a higher sensitivity. These results demonstrate the potential of gray TiO2/SrTiO3 for humidity sensing applications