RETRACTED ARTICLE: Polydopamine-modified MWCNT/graphene oxide hybrid 3D carbon nano-structure for flexible symmetric supercapacitor electrodes

Abstract

The nanocarbon-based three-dimensional carbon nano-structure was prepared from the combination of one-dimensional multi-walled carbon nanotubes (MWCNTs) and two-dimensional graphene oxide by a simple hydrothermal method. The MWCNT/graphene hybrid hydrogel (CGOH) was used as electrode, and it exhibited higher specific capacitance (193.3 F g−1) compared to graphene oxide hydrogel (62.5 F g−1) due to the increase of electrical conductivity. Further enhancement of the capacitance was studied in this work by utilizing polydopamine (PDA) coating on the CGOH surface and heat treatment at 600 °C under argon gas condition for 2 h (PDA-CGOH-600). The specific capacitance of the PDA-CGOH-600 (217.4 F g−1) was enhanced by 12.5% compared to the CGOH. Using these hybrids, the flexible symmetric supercapacitor (FSS) devices were prepared with a solid polymer electrolyte (polyvinyl alcohol/sulfuric acid). The charge/discharge tests of FSS device confirmed that the highest capacitance of the FSS based on PDA-CGOH-600 because of the nitrogen-doping effect and the graphitic carbon formation. Furthermore, FSS device can be applied in the wire-shaped supercapacitor and good parameters of the energy storage device were achieved, such as specific capacitance of 50 mF cm−2, stability during 3000 times of charge/discharge, as well as stretchability and bending ability.