Layered PPy/Cr2O3 as a supercapacitor electrode with improved electrochemical performance

Abstract

In the present work, we have synthesised polypyrrole (PPy), Cr2O3 and layered PPy/Cr2O3 thin films on stainless steel (SS) substrates for electrochemical supercapacitor applications. The PPy and Cr2O3 thin films were deposited by galvanostatic electrodeposition on stainless steel substrate separately. Layered PPy/Cr2O3 thin films are prepared via electrochemical polymerization of PPy on which Cr2O3 layer was deposited by electrodeposition technique. The structural and surface morphological studies of these thin films were carried out with the help of X-ray diffraction (XRD) technique and scanning electron microscopy (SEM) images. XRD study remarks that formation of crystalline Cr2O3 and amorphous PPy while in the layered PPy/Cr2O3 structure showed no additional peaks. The formation of polypyrrole in layered PPy/Cr2O3 was confirmed by Fourier transform infrared (FTIR) spectroscopy. The SEM images showed favourable morphology for supercapacitive study. Furthermore, the electrochemical supercapacitive properties were studied by cyclic voltammetry (CV), galvanostatic charging–discharging and electrochemical impedance spectroscopy (EIS) techniques. The layered PPy/Cr2O3 thin film showed higher coulombic efficiency of 97% and specific power 49.75 kW kg−1 at current density of 0.5 mA cm−2. In addition to this, the layered PPy/Cr2O3 thin film showed higher cycling stability than that of pure PPy and Cr2O3 thin film electrodes. This may be due to outstanding electrochemical properties that are mainly attributed to the synergistic effect between PPy and Cr2O3 and its novel architecture.