Porous ZnAl2O4 spinel nanorods: High sensitivity humidity sensors

Porous zinc aluminate (ZnAl2O4) spinel nanorods were synthesized via a homogeneous co-precipitation approach followed by a heat treatment at 900 °C. The porous rod-like nanostructures not only increase the efficiency of adsorption sites, but also promote the dissociation of water adsorbed on nanorod boundaries and pore-walls. Moreover, they also provide an effective and fast channel for the transport of water vapor and liquid. Therefore, the impedance signal of the sensors based on the porous nanorods presents high sensitivity, good linearity, small hysteresis, and fast response/recovery time to humidity. Additionally, the sensors are also relatively stable to humidity for a long time. This study demonstrates that porous ZnAl2O4 nanorods are a promising platform for the construction of humidity sensors.