Synthesis, Electrical and Humidity-Sensing Properties of PANI-Metal Oxide Nanocomposites

This study synthesised polyaniline (PANI)-based nanocomposites incorporating silica (SiO ₂ ), titanium dioxide (TiO ₂ ) and zinc oxide (ZnO), and evaluated their humidity sensing performance. The nanocomposites were prepared via in situ oxidative polymerisation, followed by ultrasonication for 40 minutes before electrospinning onto silver electrodes to form humidity-responsive films. Relative humidity (RH) environments ranging from 11% to 93% were established using saturated salt solutions, with sensing performance evaluated through resistance measurements. All PANI-metal oxide nanocomposites exhibited a marked exponential decrease in resistance with increasing humidity, indicating favourable moisture adsorption capacity and proton conductivity. Among these, the PANI–SiO ₂ nanocomposite exhibited the highest sensitivity, attributed to its favourable hydrophilicity and surface-rich silanol groups, which facilitate multilayer water adsorption. The PANI–TiO ₂ nanocomposite achieved a favourable balance between high sensitivity and interfacial charge transfer, while PANI–ZnO demonstrated more linear and repeatable response behaviour. In contrast, pure PANI without oxide additives performed the weakest. The findings indicate that the introduction of metal oxides combined with ultrasonic treatment exhibits significant synergistic effects in enhancing the structural uniformity, interfacial interactions, and overall sensing performance of PANI-based nanocomposites, demonstrating their broad prospects for application in high-performance humidity sensors.