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Khanra P.,Advanced Materials Research Institute for BIN Fusion Technology | Uddin Md.E.,Advanced Materials Research Institute for BIN Fusion Technology | Kim N.H.,Advanced Materials Research Institute for BIN Fusion Technology | Kuila T.,Indian Central Mechanical Engineering Research Institute | And 3 more authors.
RSC Advances

An efficient approach for the preparation of 9-anthracene carboxylic acid (ACA) modified reduced graphene oxide (rGO) was demonstrated in this study. ACA was used as a surface-modifying agent and underwent a reversible redox reaction. The benzene ring of the ACA anion was attached to the rGO surface via π-π interactions, and the carboxylate anions helped to disperse the hybrid materials in water due to hydrogen bonding. Therefore, water-dispersible, ACA-modified rGO (ACA-rGO) improved the wettability and capacitance performance in aqueous electrolyte solutions. The morphology of the ACA-rGO was studied using transmission electron microscopy and atomic force microscopy image analysis. The dispersion characteristics of the exfoliated materials were investigated using UV-vis spectroscopy analysis. The chemical states and natures of the samples were investigated using Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy (XPS). The appearance of a new peak at 288.7 eV in the XPS of ACA-rGO confirmed the successful surface modification of rGO using ACA. Raman spectra were studied to compare the electronic structure and defect concentrations in the ACA-rGO with respect to GO. The low intensity and shifted D- and G-bands indicated non-covalent functionalization of rGO with ACA anions. Electrochemical performances of ACA-rGO, rGO, and GO were evaluated in 1 M aqueous Na2SO4 electrolyte. The capacitance performance was investigated through galvanometric charge-discharge with ACA-rGO, rGO, and GO in an operating voltage of -1 to 1 V. The range of specific capacitance in the three-electrode system was 610 to 115 F g-1 at a current density range of 0.8 to 20 A g-1. In addition, the capacitance performance of ACA-rGO was studied in 1 M Na2SO4 electrolyte using two-electrode systems. The cell capacitance, energy density, and power density at a current density of 0.2 A g-1 of the asymmetric assembly with multiwall carbon nanotubes were 77 F g-1, 41.3 Wh kg-1, and 200 W kg-1, respectively. © The Royal Society of Chemistry 2015. Source

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