Temperature dependent morphological evaluation of spray pyrolysed TiO2 thin films prepared via aqueous route: electrochemical characterizations

Abstract

Low temperature spray pyrolysis technique was used for the synthesis of mesoporous TiO2 thin films for electrochemical supercapacitor. 0.06 M aqueous solution of potassium titanium oxalate (PTO) was used to synthesize the quality thin films on stainless steel by varying decomposition temperatures from 573 to 723 K by the interval of 50 K. Uniform porous growth of TiO2 nanoparticles was confirmed by TEM and SEM. XRD study illustrates rutile tetragonal crystalline structure of the deposit at low decomposition temperature and EDX pattern confirms formation of a pristine TiO2. The wetting of surface and surface area analysis (BET) shows that the angle of contact varying from 59° to 33° and increase in surface 10.72–15.88 m2 g−1 by varying decomposition temperature respectively. The observed average pore diameter and average pore volume for optimized sample by BJH method is 3.775 nm and 0.066 cm3 g−1 respectively. Cyclic voltammetery shows maximum SC 737.1 F g−1 at 2 mV s−1 scan rate in 1 M NaOH. The highest values of specific energy (SE) 10.50 Wh Kg−1, specific power (SP) 46.66 KW Kg−1 and columbic efficiency (η) 98.00% were observed using galvanostatic charge–discharge method. Observed internal resistance was 0.9786 Ω evaluated using electrochemical impedance spectroscopy (EIS) and the achieved maximum value of specific capacitance is stable up to 2000 cycles, which is more feasible for supercapacitor application.