Robust Dual-Color Electrochromism of Vanadium Oxide Nanorods Embedded on Reduced Graphene Oxide: Unraveling the Mechanism

Abstract Vanadium pentoxide (V2O5), associated with both cathodic and anodic coloration, is considered as one of the best electrochromic (EC) materials for energy-saving smart electronics. Here we present the fabrication as well as detailed mechanism analysis for improvement of the electrochromic properties of V2O5 incorporated in a reduced graphene oxide (rGO) matrix using a facile wet chemical method. The microstructural study disclosed formation of prominent V2O5 nanorods embedded on rGO matrix. The optimized electrochromic film resulted into coloration (tc) and bleaching time (tb) of ~ 6.2 and ~ 4.8 s, respectively, much faster than the color switching kinetics of the pristine V2O5 sample (tc ~ 19.4 s, tb ~ 15.3 s). The more dispersed structure also ensured an approximate 400% enhancement in the optical modulation of EC film and reflected a noticeable improvement in the coloration efficiency (~ 347 cm2/C) of V2O5 film. Modification with rGO resulted in an outstanding improvement in the electrochemical redox stability of V2O5 up to 5000 CV cycles with minimum deterioration in the curve area. The formation of nanorod structure was the prime factor for better ion diffusion and thereby facilitating enhanced performance.