Electrochromic Properties of Ni/NiO/rGO Nanocomposite Films Prepared by a Facile Sol-Gel Technique

Transparent electrochromic nickel oxide films with Ni-rGO (reduced graphene oxide) co-doping were deposited on ITO substrates by a facial sol-gel method. The structure characterization of the composite film was carried out by XRD, SEM and TEM, and proposed the growth model to illustrate the fabrication process. The electrochromic properties of Ni/NiO/rGO films have been studied in 1 mol/L KOH aqueous electrolyte via cyclic voltammetry, chronoamperometry and visible light transmission. The optimum Ni/NiO/rGO composite films with a thickness about 80 nm exhibits the maximum anodic/cathodic diffusion coefficient of 6.28 x 10(-9) cm(2) . s(-1)/4.94 x 10(-9) cm(2) . s(-1) and outstanding electrochromic properties, including the stable and reversible coloration-bleaching cycles, and large coloration efficiency (48.15 cm(2) . C-1), as well as large transmittance modulation (51.6%) and fast coloration/bleaching response speed (4.2 s/2.4 s) at a wavelength of 550 nm. These characteristics open the possibility to the industrial applications, particularly for the large-area electrochromic devices. (c) 2017 The Electrochemical Society. All rights reserved.