Method for preparing highly dispersed Pt catalysts on mesoporous carbon support

Two Pt catalysts supported on template-synthesized mesoporous carbons (MC) were prepared by the conventional wet-impregnation method (Pt-impreg/MC) and by the less commonly used colloidal deposition method (Pt-coll/MC) to examine the effect of preparation method on catalyst performance. The catalysts were characterized by transmission electron microscopy, field-emission electron microscopy, thermogravimetric analysis and X-ray diffraction. The electro-oxidation of methanol in acidic solutions for direct methanol fuel cells at room temperature was used as the test reaction. CO anodic stripping voltammetry and cyclic voltammetry both recorded enhanced performance for Pt-coll/MC relative to Pt-impreg/MC. The poorer application performance of Pt-impreg/MC can be attributed to the transport resistance in the mesopores, and to the entrapment of a sizable fraction (40%) of Pt nanoparticles in the mesopores which are not readily accessible to the reactants under the reaction conditions.