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Substrate Ligand Effects on Atomically Thin 2D Platinum on Graphenated 3D Structures

Tuesday, 15 May 2018: 17:40
Room 201 (Washington State Convention Center)
C. Arnold, P. Buntin (Georgia Institute of Technology), J. H. Warner (University of Oxford), J. Kacher (Georgia Institute of Technology), A. Abdelhafiz (School of Mat. Sci. & Engr. Georgia Institute of Technology), and F. M. Alamgir (Georgia Institute of Technology)
This work explores the novel concept of electrochemically deposited wetted monolayer to few multilayers of Pt on a graphenated 3D Ni foam (Pt-ML/GR/Ni). Commercially available, highly porous, Ni foam capped with graphene was utilized as a substrate for layer-by-layer Pt growth by surface-limited electrochemical deposition. A survey of literature reveals that our resulting Pt-ML/GR/Ni architecture is the first instance of 3D rendered graphene being used as a template for 2D Pt growth via room-temperature synthesis. XPS, CV, SEM/EDS and high-resolution TEM characterization reveals that graphene covers much of the Ni foam and that the Pt grows epitaxially on the graphene. This scheme allows us to approach theoretical limits of Pt utilization for electrocatalytic applications, such as the canonical oxygen reduction reaction (ORR). Analysis of the ORR overpotential in Pt-ML/GR/Ni in comparison to that of the Ni-free Pt-ML/GR shows that the Dirac cone of the Pt/GR is intact, making the graphene essentially ‘electron transparent’ to the Ni-to-Pt charge transfer. Such Pt-ML/GR architectures can thus allow the surface Pt atoms to be electronically tuned by an underlying ligand of choice. This synthesis approach may prove extremely valuable for high-utilization, low-loading, electronically tunable catalysts. We present here a thorough investigation of the atomic/electronic structure and of the related evolution of electrocatalytic properties as a function of the number of graphene-templated 2D Pt layers.