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A unique synthesis was developedto immobilize Pd nanoparticleson pristine graphene (PG) sheets via a facile supercritical carbondioxide route. Pristine graphene was obtained by sonication-assistedexfoliation of graphite in an organic solvent. Finely dispersed worm-likePd nanoparticles are homogeneously deposited on the hydrophobic graphenesurfaces. The combination of pristine graphene sheets and well-dispersedPd nanoparticles provided large electrochemically active surface areas (ECSA) for bothdirect formic acid fuel cell (DFAFC) and methanol fuel cell (DMFC).The ECSA values are more than twice as large as those of reduced grapheneoxide and carbon nanotube based counterparts or six times those ofconventional XC-72 carbon black. Significant enhancements were alsoobserved in the electrocatalytic activity and stability measurements.The excellent electrochemical property of Pd/PG is attributable tothe well-preserved graphene structure that ensures electrical conductivityand stability of the composite. Its large surface area also allowsfor the deposition of small size and high dispersion of the Pd nanoparticles.This straightforward synthesis offers a new pathway for developinghighly active electrocatalysts based on pristine graphene with fullyoptimized properties. [ABSTRACT FROM AUTHOR]