Local CO Behaviour on Polycrystalline Pt Electrode Surface Using Compressive Sensing Sum Frequency Generation Microscopy (CS-SFGM) Combined with Electrochemistry
| Dates: | 17 March 2021 |
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| Times: | 13:00 - 14:00 |
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| What is it: | Seminar |
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| Organiser: | Photon Science Institute |
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| Who is it for: | University staff, Current University students |
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| Speaker: | Professor Steven Baldelli |
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Join us for this PSI seminar with guest speaker Prof. Steven Baldelli. Compressive sensing sum frequency generation microscopy (CS-SFGM) was applied to study the CO adsorption on the polycrystalline Pt electrode surface. The crystal facets of heterogenous polycrystalline Pt domains were determined by electron backscatter diffraction (EBSD). The SFG images stack obtained from broadband IR system contains the spectroscopic information of CO for in-situ adsorption behaviours study. Localized SFG spectra of C?O stretching mode revealed the difference of CO behaviours on different crystal domains compared to the average spectrum. By controlling the potential applied on polycrystalline Pt surface, the Stark shift effect of each crystal domains was studied. The SFG spectra were fitted at every single pixel to map the peak wavenumber and Stark shift values distribution of C?O stretching mode. The peak wavenumber map shows obvious boundaries between each domain while the Stark shift values map shows the non-local distribution across the whole surface. The preliminary results below suggest a possible mechanism for this effect and the outcome of the study will be an order-of-magnitude improvement in our understanding of the surface chemistry of practical, real systems, for both catalysis and corrosion. CO adsorbed to different crystal facets in a polycrystalline Pt electrode sample exhibits a vibrational resonance depending on the crystal plane to which it is bonded but is different than that of the externally prepared single crystal. However, the electrochemical vibrational Stark shift tuning rate d?/dV is very similar for each domain suggesting a levelling effect in the electronic structure and dependent on the localized grain structure arrangements. Thus while the study of single crystals is of great importance, the domains embedded in a polycrystalline matrix exhibit different surface chemistry, and this study represent a systematic controlled study to help bridge the ‘materials gap’ that exists in fundamental surface science studies.
This event will be taking place online and furthers details about the event and how to join will be made available shortly.
Speaker
Professor Steven Baldelli
Organisation: University of Houston
Biography: Steven Baldelli is a professor of chemistry at the University of Houston. Born in Framingham Massachusetts. He received his BS in chemistry at Framingham State College in Framingham, Massachusetts and Ph.D. in chemistry from Tufts University with Mary Shultz. His postdoctoral work was at the University of California, Berkeley with Gabor Somorjai and Phil Ross. Since at the University of Houston, his research has focused on; surface chemistry of ionic liquids, corrosion an inhibition of metals, electrocatalysis, surface adsorption, electrochemistry, and nonlinear optical microscopy
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