Rapid synthesis of cerium oxide nanoparticles with superior humidity-sensing performance

This paper reports a simple and rapid microwave-assisted method for synthesizing cerium oxide (CeO2) nanoparticles for the fabrication of high-performance humidity sensors. The humidity-sensing investigation reveals that the sensor based on CeO2 nanoparticles exhibits a high and linear response within the entire relative humidity (RH) range of 11–97% at an operating frequency of 60 Hz. The corresponding impedance changes by approximately three orders of magnitude within the entire humidity range from 11% to 97%. The response and recovery times are approximately 3 and 16 s, respectively. Additionally, the sensor exhibits a rapid and reversible response characterized by a very small hysteresis (∼1%RH), excellent repeatability, long term stability and a broad range of operation (11–97%RH). The Nyquist impedance plots of the sensor at different RHs were used to elucidate the sensor's humidity-sensing mechanism via an electrical equivalent circuit. The experimental results provide a possible method for the rapid synthesis and fabrication of high-performance humidity sensors based on CeO2 nanoparticles.