Synergistic effect of biomass-derived carbon and conducting polymer coatings on the supercapacitive energy storage performance of TiO2

The application of anatase titanium dioxide (TiO2), which is an abundant and cost effective resource, in supercapacitors has been restricted due to its poor electronic conductivity and limited mechanical stability. A biomass-derived carbon was coated on anatase TiO2 nanoparticles via practical and green hydrothermal carbonization in order to overcome these limitations. Hierarchically porous carbon provided a capacitive double layer for charge storage and the TiO2/C nanocomposite exhibited a specific capacitance of 61 F × g-1 (0.25 A × g-1, 0 to 1 V vs. Ag/AgCl, 1 M H2SO4 aqueous electrolyte). The TiO2/C/PEDOT:PSS nanocomposite with enhanced specific capacitance and rate capability (189 F × g-1 at 0.25 A × g-1, 161 F × g-1 at 0.5 A × g-1, 123 F × g-1 at 1 A × g-1, 91 F × g-1 at 2 A × g-1) was obtained by the application of an electrochemically active PEDOT:PSS layer. The prominent electrochemical and mechanical stability of the ternary nanocomposite was demonstrated by its ability to retain 98 % of its initial capacitance after 1500 cycles of charge-discharge at a high current rate (3 A × g-1). The synergistic use of sustainable organic and inorganic components with environmentally friendly and practical methods yields extremely promising electrochemical performances for supercapacitor applications. The TiO2/C/PEDOT:PSS nanocomposite presented in this work delivered an electrochemical performance comparable to its published counterparts which are obtained by more sophisticated or hazardous methods and with expensive components.