AVS 63rd International Symposium & Exhibition
    Fundamental Discoveries in Heterogeneous Catalysis Focus Topic Wednesday Sessions
       Session HC+SS-WeM

Paper HC+SS-WeM12
The Use of EC-STM to Study the Chemical Reactivity and Nanoscale Structure of Metal Surfaces

Wednesday, November 9, 2016, 11:40 am, Room 103A

Session: Bridging Gaps in Heterogeneously-catalyzed Reactions
Presenter: Erin Iski, University of Tulsa
Authors: A. Phillips, University of Tulsa
L. Jackson, University of Tulsa
H. Morgan, University of Tulsa
G. Jones, University of Tulsa
E.V. Iski, University of Tulsa
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In the development of surfaces as efficient catalysts, it is critical to understand and control the surface reactivity in a defined manner. Electrochemical Scanning Tunneling Microscopy (EC-STM) is an advantageous technique in that in addition to providing a local probe of the atomic surface structure, EC-STM also functions as a 3-electrode cell in which redox chemistry can be performed to harness the chemical reactivity of the surface. This technique offers a unique window to study catalysis at conditions outside of a UHV environment, specifically at ambient temperatures and in liquids. Also, cyclic voltammograms (CVs) can be generated to provide specific information regarding the nature of the redox events occurring at the surface. Within this framework, it is possible to study how certain surfaces can become activated and/or deactivated as a result of electrochemical manipulation. One specific example of a thermally deactivated surface is a single Ag layer on a Au(111) crystal. The Ag layer is deposited on the Au(111) surface using Underpotential Deposition (UPD), which is an extremely controllable electrochemical technique for the application of a monolayer (or less) of a metal onto a more noble metal. Surprisingly, this atomically-thin Ag layer when formed in the presence of halides remains on the Au surface after heat treatments as high as 1,000 K. Importantly, thermal stabilization can be contrasted and compared with catalytic activity in which chlorine has shown to be a promoter of ethylene epoxidation over Ag(111), demonstrating why this system is intriguing from multiple vantage points. From a general standpoint, EC-STM offers an environmentally unique handle on how the chemical reactivity of a metal surface can be altered and how that surface can then be studied on a fundamental level.