A facile method to graphene oxide/polyaniline nanocomposite with sandwich-like structure for enhanced electrical properties of humidity detection.

In this paper, a novel graphene oxide (GO)/polyaniline (PANI) sandwich-like nanocomposite has been synthesized by in-situ chemical oxidative polymerization. The GO/PANI is then fabricated onto the interdigitated transducers as sensor for humidity detection. The electrical properties of the thin films are investigated in various relative humidity (RH), including conduction mechanism, sensitivity, reproducibility and humidity hysteresis. The conduction mechanism of the GO/PANI for humidity response is discussed in detail, and the total resistance of GO/PANI is mainly depending on the bulk resistance of PANI. At the lower (60%) RH, the proton hopping transfer plays a very important role for the proton exchange mechanism of GO/PANI thin film. At the higher RH, ionic conduction is not only main conduction process, but also with the proton hopping partially exists for the proton exchange mechanism. Besides, the humidity sensitivity of the thin films enhances with increasing the mass ratio of GO (0, 5, and 50 mg) to PANI due to its larger surface area, hydrophilic functional groups and synergistic effect of π-π* conjugation system, which is also supported by adsorption of QCM humidity response. Meanwhile, the morphology and structure of the thin films are analyzed by fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM) and transmission electron microscope (TEM), respectively.