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

Vanadium pentoxide (V 2 O 5 ), 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 V 2 O 5 incorporated in a reduced graphene oxide (rGO) matrix using a facile wet chemical method. The microstructural study disclosed the formation of prominent V 2 O 5 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 V 2 O 5 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 cm 2 /C) of V 2 O 5 film. Modification with rGO resulted in an outstanding improvement in the electrochemical redox stability of V 2 O 5 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.