Multifunctional electrochromic hybrid PANI@WO3 core-shell for energy generation and storage

Abstract

Materials that can be deposited easily and shows multifunctional application are always in demand. Two technologically important materials, polyaniline (PANI) and tungsten trioxide (WO3) have been amalgamated using an uncommon, yet simple, technique of deposition, chronoamperometry to obtain a hybrid core-shell structure and its application in three different areas of electrochromic display, electrocatalysis and energy storage has been investigated. Electrodepositing WO3 and PANI onto highly conducting substrates one on top of other, resulted in formation of PANI (shell), WO3 (Core) (PANI@WO3) electrode resulting in a highly uniform fibrous surface structure. Electrochemistry performed using the conventional three electrode step up suggested a very good charge storing capacity, stability also indicating a pseudo capacitive nature which was later confirmed with the help of Nyquist plot. Besides very good values of areal capacitance (855 mF/cm2), power density (6.5 kW/cm2) and energy density (1.09 kWh/cm2) established its supercapacitive performance. Next, its behaviour as an electrocatalyst was studied by duly plotting polarisation curves and their corresponding Tafel plots. The PANI@WO3 electrode deposited on a transparent electrode exhibited green-blue-yellow-transparent color switching under different bias conditions with a very small voltage of 0.5 V. A fast switching of 0.4 s and a great color contrast of ∼50 % in visible as well IR region were displayed making the electrochemically deposited core-shell a good candidate for multifunctional application in energy generation, storage with an inerrability with smart electrochromic windows.