Electrochromic polyaniline/graphite oxide nanocomposites with endured electrochemical energy storage

Abstract

Polyaniline (PANI)/graphite oxide (GO) nanocomposite films were fabricated by electropolymerization of aniline monomers onto GO coated indium tin oxide (ITO) glass slides, which were prepared by spin coating technique. The morphology as well as the crystalline structure of the composite films were studied using Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM), and X-ray diffraction (XRD). The results confirm the obtained composite structural films and the interactions between the polymer matrix and the GO particles. The optical properties and the electrochemical capacitive behaviors of the composite films for electrochromic displays and electrochemical energy storage devices applications were investigated using the spectroelectrochemistry (SEC), cyclic voltammetry (CV) and galvanostatic charge–discharge measurements. The composite films show multi-color electrochromism at different potentials arising from PANI. A coloration efficiency of 59.3 cm2 C−1 is obtained for the composite film, higher than that of the pure PANI thin films, 50.0 cm2 C−1. An areal capacitance of 25.7 mF cm−2 that is comparable to PANI (75.1 mF cm−2) is derived from the CV at a scan rate of 5 mV/s with a broader working potential window of 1.3 V. The cyclic stability studies reveal that the composite films exhibits much more enhanced durability and retains 53.1% of the capacitance even after 1000 charge–discharge galvanostatic cycles. However, the pure PANI thin films lose almost most of the charge storage or discharge capacity even after 350 cycles. The interactions between PANI matrix and GO particles are believed to be responsible for the observed enhanced stability in the nanocomposite films.