Effect of pH-induced chemical modification of hydrothermally reduced graphene oxide on supercapacitor performance
KAUST DepartmentMaterials Science and Engineering Program
Physical Sciences and Engineering (PSE) Division
Advanced Membranes and Porous Materials Research Center
Functional Nanomaterials and Devices Research Group
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AbstractThree 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.
SponsorsAuthors 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.
JournalJournal of Power Sources