High-temperature humidity sensors based on WO3-SnO2 composite hollow nanospheres

摘要

Three kinds of humidity sensors were fabricated from WO3-SnO2 composite hollow nanospheres (WO3-SnO2 HNS), WO3 nanoparticles (WO3 NPs) and SnO2 nanoparticles (SnO2 NPs). WO3-SnO2 HNS were prepared by a facile hydrothermal process with a diameter and thickness of about 550 nm and 30 nm, respectively. Temperature-dependent properties of as-prepared humidity sensors were investigated at various values of relative humidity and temperature. It was found that the WO3-SnO2 HNS humidity sensor showed good performance at 80 °C. The response time, recovery time and sensitivity were evaluated while switching the humidity between 35% RH and 98% RH. The response time decreased from 289 to 29 s, the recovery time reduced from 22 to 8 s, and the sensitivity changed from 16.2 to 11.4 as the work temperature was raised from 24 to 80 °C. An opposite humidity sensing phenomenon was observed between WO3 NPs and SnO2 NPs at a high temperature, which might explain the temperature-dependent properties of the WO3-SnO2 HNS humidity sensor. This work could stimulate a right approach to design practical humidity sensors with high sensitivity, long stability and fast response.