Mesoporous GO-TiO2 nanocomposites for flexible solid-state supercapacitor applications

Abstract

Fabrication of flexible solid-state supercapacitor is a field of paramount importance because of its potential application in portable devices. In this article, graphene oxide and titanium dioxide hybrid (GO-TiO2) nanocomposites of different compositions are employed for the fabrication of flexible solid-state supercapacitors. An easy, fast, scalable and controlled sol-gel method is devised for GO-TiO2 nanocomposites growth from different amounts of graphene oxide and titanium isopropoxide at atmospheric pressure. Highly monodispersed rutile TiO2 nanospindle is homogenously grafted on GO by a controlled HCl catalyzed reaction. BET N2 adsorption desorption isotherm analysis confirms formation of the mesoporous structure having a large specific surface area favourable for faster reversible adsorption and desorption of ions. An optimum composition of GO-TiO2 nanocomposite (TG25) exhibits a high areal specific capacitance of 73.43 mF cm−2 at a current density of 0.5 mA cm−2 due to formation of electrical double layer in a solid-state supercapacitor. The fabricated device shows high power density (3.5 mW cm−2), a high energy density (0.007 mWh cm−2), good flexibility and excellent cycling stability, 92% specific capacitance retention after 10,000 continuous charge-discharge cycles. Finally, three supercapacitors in a series have illuminated a red LED, indicating the nanocomposite as a potential candidate for energy storage technology.