Chemical aging of Nafion: FTIR study

In this paper, a capacitance humidity sensor which was fabricated by interdigital electrodes (IDEs) coated with Nafion/graphene oxide quantum dot (GOQD) thin film was reported. The sensor could convert concentration change of moisture into capacitance change of the IDEs. The morphological and nanostructure of the prepared Nafion/GOQD nanocomposite were characterized by the scanning electron microscopy (SEM), transmission electron microscopy (TEM), confirming that the Nafion/GOQD nanocomposite was successfully prepared. Test result showed that the proposed sensor exhibited higher sensitivity of 1025.99 pF/%RH (nearly double) and better linearity, compared with pure Nafion sensor, which could be ascribed to formation of a subordinate-assembly of 0D GOQD in the Nafion film. Furthermore, the humidity sensor exhibited excellent repeatability, fast response and recovery, and little hysteresis. It could offer a potential method to monitor the respiration. Lastly, the humidity sensing mechanism was studied through complex impedance spectra (CIS).