High performance humidity sensors based on CeO2 nanoparticles

Abstract CeO 2 is a good humidity sensitive material, which has been widely investigated by using direct current (d.c.) analysis method. In this paper, we used the complex impedance analysis method to analyze CeO 2 nanoparticles (NPs). It was found that the impedance as a function of humidity exhibited the best linearity and smallest hysteresis at 1 KHz than the capacitance or resistance did. The complex impedance modulus (| Z |) varied by four orders of magnitude from 3.8 × 10 7  Ω to 4.3 × 10 3  Ω in the humidity range of 11–98% RH. The value of the linearity fit correlation ( R 2 ) was 0.997. The sensor exhibits a rapid and reversible response characterized by a very small hysteresis (∼2% RH). The response time and recovery time were 10 s and 3 s, respectively. These results further demonstrated promising application of CeO 2 as humidity sensor.