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.