Characterization and humidity sensitivity of electrospun ZrO2:TiO2 hetero-nanofibers with double jets

ZrO2:TiO2 hetero-nanofibers composite was synthesized via electrospinning with double jets based on positive and negative polarity electric fields. The hetero-nanofibers were characterized by using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). ZrO2:TiO2 composite shows a netted hetero-nanofibers structure with interleaving of two different diameters nanofibers. Humidity sensors were fabricated based on ZrO2:TiO2 hetero-nanofibers. The impendence of the sensor changed four orders of magnitude from 105 to 101 kΩ in relative humidity (RH) range of 11–97% at 25 °C. The max humidity hysteresis was around 5% RH, and the response and recovery times were less than 5 s and 20 s, respectively. The properties of impendence vs. RH at different temperatures were discussed. Overall, the humidity sensor of ZrO2:TiO2 hetero-nanofibers exhibited good sensing characteristics. The humidity sensing mechanism was analyzed via dielectric loss and equivalent circuit.