Preparation and humidity sensitive property of mesoporous ZnO–SiO2 composite

Mesoporous ZnO–SiO2 composites with various Si/Zn molar ratios were synthesized through a simple one-pot sol–gel method and their humidity sensing properties were also examined. Compared with pure SBA-15, ZnO–SiO2 composite shows improved humidity sensing properties and the introducing level of ZnO has a great influence on the humid sensitivity of ZnO–SiO2 composites. The results exhibited that the sample with Si/Zn = 1 showed better humidity sensing properties than others within the range of 11–95% relative humidity (RH). Its impedance changed by more than four orders of magnitude over the whole humidity range. The response and recovery time were about 50 s and 100 s, respectively. High sensitivity and low hysteresis were also observed. A possible mechanism was suggested to explain the humidity sensitive properties.