Graphene single nanosheet (GNS) is synthesized from graphite by chemical oxidation and thermal exfoliation at 1000 degrees C and confirmed by X-ray diffraction analysis. Scanning electron and transmission electron microscope images clearly show the lateral expansion of graphite sheet and uniform dispersion of Pt nanoparticles on GNS. Fourier transform infrared and X-ray photoelectron spectroscopy analyses are conducted for surface properties of GNS such as oxygenated functional groups. Cyclic voltammetric analysis shows that electrochemical active surface areas (ECSAs) for Pt/GNS, commercial Pt/Vulcan XC-72 carbon black and Pt-incorporated onto commercial carbon black (Pt/CB) prepared in the laboratory are 33.1 m(2) g(-1), 23.5 m(2) g(-1) and 22.5 m(2) g(-1), respectively. Because of significant restacking of Pt/GNS sheets, carbon black (CB) with different content is intercalated between Pt/GNS as a spacer. The ECSAs of Pt/GNS, Pt/GNS/CB20, Pt/GNS/CB30 and Pt/GNS/C840 are evaluated to be 31.5 m(2) g(-1), 28.6 m(2) g(-1), 38.8 m(2) g(-1) and 30.4 m(2) g(-1), respectively. The cell performance highly depends on CB content and PtiGNS/CB with 30 wt.% of CB content shows the best cell performance of 400 mA cm(-2). (C) 2012 Elsevier B.V. All rights reserved.