Modulating Strain and Charge Transfers in Low Dimensional Catalysts through Interface Design and Templated Growth

Wednesday, 27 May 2015: 09:40
PDR 4 (Hilton Chicago)
F. M. Alamgir (School of Mat. Sci. and Engr., Georgia Inst. of Tech.) and A. Vitale (Georgia Tech)
In this presentation, we review the dimensional aspects of structure-driven surface properties of metal monolayers grown on a Au and graphene/Au templates. Here, surface limited electrodeposition is used to provide precise layer-by-layer growth of Pt monolayers. After a few iterations of SLRR, we find that fully wetted 4-5 monolayer Pt films can be grown on either template. Incorporating graphene at the Pt-Au interface modifies the growth mechanism, charge transfers, equilibrium interatomic distances and associated strain of the synthesized Pt monolayers. Capping the Pt with a single overlayer of graphene similarly affects the underlying Pt structures. X-ray photoelectron spectroscopy (XPS) and extended x-ray absorption fine structure (EXAFS) techniques are used to examine charge mediation across Pt-Graphene-Au junction and the local atomic arrangement as a function of the Pt adlayer dimension. Cyclic voltammetry (CV) and the oxygen reduction reaction (ORR) are used as probes to examine the electrochemically active area of Pt monolayers and catalyst activity, respectively. Results show that the inserted graphene monolayer results in increased activity for the Pt due to a graphene-induced compressive strain, as well as a higher retention of catalytically active Pt surface. This Pt retention extremely effective, and occurs with no compromise to ORR activity, when the Pt is capped with a graphene layer.