Investigation of the adsorption of size-selected Pt colloidal nanoparticles on high-surface-area graphene powders for methanol oxidation reaction

Graphene-supported nanoparticles (NPs) are of tremendous interests for a variety of applications recently. In this study, high-surface-area graphene powders are used for loading size-selected Pt colloidal NPs as fuel-cell catalysts for methanol oxidation reaction (MOR). It is found that the adsorption of Pt colloidal NPs on graphene surfaces is dramatically influenced by the process parameter in the mixing process. Specifically, the different solution volumes during the mixing process result in various catalyst morphologies. Pt-graphene (Pt-G) catalyst synthesized through the high-concentration solution system in the mixing process exhibits the densely-packed Pt NPs on graphene surfaces with non-flat wrinkles. Moreover, the high-density Pt NPs in the catalyst give rise to the high MOR current in its forward scan. In other words, this catalyst outperforms all the other catalysts synthesized in the low-concentration solution systems in terms of the MOR current and electrochemical surface area (ECSA). The mass activity of Pt-G-1 catalyst can reach 489.66 mA/mgPt. The appropriate loading of size-selected Pt-based NPs on graphene is significant for the controlled synthesis of catalysts for fuel-cell application.