ZIF-67 and titania derived quaternary composites as electrode materials for high-performance supercapacitor

Abstract

In this research work, three quaternary composites TZ-700 (Co3O4/TiO2/Co/NGC@700), TZ-800 (Co3O4/TiO2/Co/NGC@800), and TZ-900 (Co3O4/TiO2/Co/NGC@900) have been synthesized from metal-organic frameworks (MOFs) as electrode materials for supercapacitors. The electrochemical behavior of the prepared electrodes from TZ-700, TZ-800, and TZ-900 composites is evaluated in three different aqueous electrolytic media 1 M KOH, 1 M H2SO4, and 1 M Na2SO4. Among all the electrodes and electrolytic solutions, TZ-900 electrode exhibits the highest specific capacitance of 1617F/g at a current density of 0.5 A/g in acidic media (1 M H2SO4). These results are further inconsistent with the electrochemical surface area (ECSA) findings where TZ-900 shows the highest ECSA of 1260.50 cm2. Also, a capacitive contribution of 92 % is observed for TZ-900 in 1 M H2SO4, through Dunn’s method. The Rs (5.78) and Rct (8.51 Ω) values for TZ-900 in an acidic medium also prove it the best electrode material amongst other electrodes and electrolytes. The cyclic stability of the TZ-900 electrode when tested over 10,000 cycles shows a specific capacitance retention of 84 % at a current density of 10 A/g, making TZ-900 composite as a competent electrode material for supercapacitor applications.