Three-Dimensional\nGraphene–TiO₂–SnO₂ Ternary Nanocomposites\nfor High-Performance Asymmetric Supercapacitors

Abstract

Ternary nanocomposites synergistically combine the material\ncharacteristics\nof three materials, altering the desired charge storage properties\nsuch as electrical conductivity, redox states, and surface area. Therefore,\nto improve the energy synergistic of SnO₂, TiO₂, and three-dimensional graphene, herein, we report a facile hydrothermal\ntechnique to synthesize a ternary nanocomposite of three-dimensional\ngraphene–tin oxide–titanium dioxide (3DG–SnO₂–TiO₂). The synthesized ternary nanocomposite\nwas characterized using material characterization techniques such\nas XRD, Raman spectroscopy, FTIR spectroscopy, FESEM, and EDXS. The\nsurface area and porosity of the material were studied using Brunauer–Emmett–Teller\n(BET) studies. XRD studies showed the crystalline nature of the characteristic\npeaks of the individual materials, and FESEM studies revealed the\ndeposition of SnO₂–TiO₂ on 3DG. The BET\nresults show that incorporating 3DG into the SnO₂–TiO₂ binary nanocomposite increased its surface area compared\nto the binary composite. A three-electrode system compared the electrochemical\nperformances of both the binary and ternary composites as a battery-type\nsupercapacitor electrode in different molar KOH (1, 3, and 6 M) electrolytes.\nIt was determined that the ternary nanocomposite electrode in 6 M\nKOH delivered a maximum specific capacitance of 232.7 C g^–1 at 1 A g^–1. An asymmetric supercapacitor (ASC)\nwas fabricated based on 3DG–SnO₂–TiO₂ as a positive electrode and commercial activated carbon as\na negative electrode (3DG–SnO₂–TiO₂//AC). The ASC delivered a maximum energy density of 28.6 Wh kg^–1 at a power density of 367.7 W kg^–1. Furthermore, the device delivered a superior cycling stability\nof ∼97% after 5000 cycles, showing its prospects as a commercial\nASC electrode.