Three kinds of reduced graphene oxides are prepared by hydrothermal reduction under different pH conditions and their pseudocapacitive performances are evaluated using full-cell supercapacitor devices. The pH values are found to have great influence on the performance of the supercapacitors, achieving the highest specific capacitance value reported for hydrothermal reduced graphene oxide supercapacitors. Acidic and neutral media yield reduced graphene oxides with more oxygen-functional groups and lower surface areas but with broader pore size distributions than those in basic medium. The graphene produced in the basic solution (nitrogen-doped graphene) presents mainly electrochemical double layer (ECDL) behavior with specific capacitance of 185 F g-1, while the graphene produced under neutral or acidic conditions show both ECDL and pseudocapacitive behavior with specific capacitance of 225 F g-1 (acidic) and 230 F g-1 (neutral), respectively, at a constant current density of 1 A g-1. The influence of pH on cycling performance and electrochemical impedance of the supercapacitive devices is also presented. © 2013 Elsevier B.V. All rights reserved.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: Authors acknowledge the help from Dr M. N. Hedhili, (research scientist, Advanced Nanofabrication, Imaging & Characterization Lab, KAUST) for the XPS measurements and the help from Analytical Chemistry Core Lab (KAUST) in BET measurements. R.B.R. acknowledges the financial support from SABIC Post Doctoral Fellowship. W.C. acknowledges support from KAUST Graduate Fellowship. H.N.A. acknowledges the generous support from the KAUST baseline fund.
ASJC Scopus subject areas
- Energy Engineering and Power Technology
- Physical and Theoretical Chemistry
- Electrical and Electronic Engineering
- Renewable Energy, Sustainability and the Environment