High-sensitivity and low-hysteresis humidity sensor based on reduced graphene oxide/zinc oxide nanocomposites

This study reports the humidity sensing properties of rGO/ZnO nanocomposites with distinct compositions synthesized using one pot synthesis method. The structural and morphological properties of the samples were investigated through XRD and SEM. The XRD diffraction findings verified the presence of rGO and hexagonal ZnO phase. SEM micrographs showed the homogenous distribution of ZnO NPs on the rGO surface. Significant variations in capacitive, resistive sensitivity and response recovery behaviour were observed for rGO/ZnO NCs across 40–90 RH%. Moreover, the sensors exhibited minimal hysteresis and a fast response/recovery time with RZ2 sensor displaying quickest response/recovery time of 6/19s. The sensors also demonstrated excellent repeatability and long-term stability. The enhancement in the humidity sensing characteristics of prepared nanocomposites may be credited to the high surface area of the sensing material, providing more active sites for the water vapors as well as the high dielectric constant of water (∼ 80).