The Role of Graphene in the Growth of Pd and Pt Nanostructures Using Surface Limited Electrodeposition

Abstract

Surface limited redox replacement is an attractive catalyst synthesis technique due to its ability to precisely control the amount of deposited metal, but the deposition is generally limited to metallic surfaces. It would be preferable to use this technique directly on conductive carbon-based support materials to reduce metal loading and improve adhesion between catalyst and support, but films are difficult to achieve due to the low surface energy of carbon materials. Metal deposition via this technique is still possible, as this study demonstrates with Pd and Pt on graphene, producing nanoparticles and low aspect ratio nanostructures. Pd favored a combination of agglomerated nanoparticles and Cl-based films that were highly influenced by the alignment of the graphene as seen in STEM. Pt tended to form isolated nanostructures with an average width-to-height aspect ratio of 2. Lattice planes are typically visible in STEM images, and, through their structure and orientation, both types of structures show signs of epitaxial relation with graphene as a growth substrate.