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 and detailed mechanism analysis for improving the electrochromic properties of V₂O₅ incorporated in a reduced graphene oxide (rGO) matrix using a facile wet chemical method. The microstructural study disclosed the formation of prominent V₂O₅ nanorods embedded in the rGO matrix. The optimized electrochromic film resulted in coloration (t_c) and bleaching time (t_b) of ∼6.2 and ∼4.8 s, respectively, much faster than the color switching kinetics of the pristine V₂O₅ sample (t_c ∼ 19.4 s, t_b ∼ 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.