Phase-dependent electrochemistry of TiO2 nanocrystals for supercapacitor applications

•Nanocrystals of TiO2 were prepared in pristine and composite forms.•XRD results reveal the multiphase formation.•Anatase phase of TiO2 shows higher BET surface area, pore size and pore volume.•Low Rct and higher BET surface area exhibit enhanced capacitance for TiO2-A.

In the present work, we demonstrate the electrochemistry of nanocrystalline TiO2 in anatase (TiO2-A), anatase/rutile (TiO2-C) and rutile (TiO2-R) phases. Cyclic voltammetry (CV), galvanostatic charge-discharge, and electrochemical impedance spectroscopy were the techniques we employed to analyse the electrochemical properties of the electrodes. The observed results suggest that the electrode of TiO2-A possesses superior electrochemical properties due to its enhanced BET surface area, porous structure and low charge transfer resistance. At a low scan rate of 10 mV/s, CV analysis results imply a capacitance of 362 F/g for TiO2-A. Moreover, the galvanostatic charge-discharge study gives a specific capacitance of 312 F/g at a low scan rate of 10 A/g. Based on the higher energy density (882 W h kg− 1) and power density (1260 kW kg− 1), the TiO2-A electrode is a promising electrode material for fabricating supercapacitors.

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