Electrochromic properties of nanoporous Co3O4 thin films prepared by electrodeposition method

The nanoporous Co₃O₄ film was prepared by an electrodeposition method. The surface morphology and composition of the nanoporous Co₃O₄ film were characterised by scanning electron microscopy, energy-dispersive X-ray analysis and X-ray photoelectron spectroscopy. The electrochromic properties of Co₃O₄ film are investigated in an aqueous alkaline electrolyte (0.1 M KOH) by means of transmittance, cyclic voltammetry and chronoamperometry measurements. The as-prepared nanoporous Co₃O₄ film exhibits a noticeable electrochromism with reversible colour changes from pale yellow to dark blue and fast switching speed (3.0 and 2.6 s).