Supercritical Carbon-Dioxide-Assisted Deposition of Pt Nanoparticles on Graphene Sheets and Their Application as an Electrocatalyst for Direct Methanol Fuel Cells

A combination of graphene with metal particles is particularly attractive due to the enhanced performance of the hybrid materials. However, direct loading of uniform metal nanoparticles such as Pt on graphene remains a challenge due to the hydrophobic nature of graphene. We herein demonstrate that Pt nanoparticles with uniform size and high dispersion were deposited on graphene surfaces via a facile and efficient supercritical fluid method. The graphene sheets used in this work were produced by rapid thermal expansion of graphite oxide. With the help of supercritical carbon dioxide (SC CO2), Pt nanoparticles with a mean size of 3.28 nm are evenly distributed on graphene upon the reduction of an organic platinum precursor. The electrocatalytic investigations reveal that the current density of methanol electrooxidation with the resultant Pt/graphene catalyst was similar to 3.5 times as large as that observed with conventional Pt/carbon black (Vulcan XC-72) catalyst. The results demonstrate that graphene serves as an excellent electrocatalytic carrier, and the supercritical fluid strategy is powerful and promising for the synthesis of highly active electrocatalysts for direct methanol fuel cells.