Paper SS1-WeM5
Carbon-induced Nano-Faceting of Re(11-21): Synthesis and Performance of a Pt ML-C/Re(11-21) Electrocatalyst

Wednesday, November 2, 2011, 9:20 am, Room 107

Faceted surfaces can provide unique opportunities to explore how catalytic reactions respond to changes in the catalyst surface structure. In this study, using LEED, XPS, AES, and STM, we report on how the presence of surface carbon significantly modifies the surface structure of a Re(11-21) single crystal and causes faceting, i.e., an initially planar Re(11-21) surface becomes “nano-textured” to expose new crystal faces and form “pyramids” on the nanometer scale. In addition to describing these nanostructures, we identify different states of surface carbon and describe their dependence on the coverage of carbon. We also utilized the faceted Re(11-21) surface containing these nanoscale pyramids to explore for unusual catalytic properties. Here, we describe the synthesis of a model electrocatalyst by deposition of one monolayer of Pt on the faceted C/Re(11-21) surface and investigation of its performance for the hydrogen evolution reaction (HER). This Pt ML-C/Re(11-21) surface displayed higher activity for the HER than pure Pt. This is particularly promising since Re is only one-fifth the price of Pt. This study is the first application of using a nanoscale faceted surface as a template for electrocatalyst synthesis, and illustrates the potential for other such investigations. It is also of interest to further explore the catalytic activity of such faceted surfaces for heterogeneous catalytic reactions, e.g., selective reduction of NO_x with NH₃ and selective oxidation of methanol, in order to understand the various effects of facet size, orientation, and low-coordination sites that are available for reaction.

W.C. and R.A.B. acknowledge support under DOE Contract No. DE-FG02-93ER14331. B.E.K. acknowledges support by NSF Grant No. CHE-1129417.