Department of Physics, Engineering Physics & Astronomy

Department of Physics, Engineering Physics & Astronomy
Department of Physics, Engineering Physics & Astronomy

Temperature-dependent surface electrochemistry hydrogen and sulfur. What new do we learn? Does it serve any good purpose?

Gregory Jerkiewicz
Department of Chemistry, Queen's University

Wednesday, November 13, 2002
10:30 AM @ Stirling 501

Abstract:

Since the development of non-UHV based techniques for preparation of well-ordered single-crystal surfaces for experimental research, electrochemical surface science has been undergoing a spectacular evolution. The prospect of conducting research on well-defined surfaces in a standard electrochemical cell opens a new scientific avenue temperature-dependent research. Experiments on Pt(100) and Pt(111) electrodes revealed noticeable T-dependence of cyclic-voltammetry profiles for the under-potential deposition of H (UPD H) and anion adsorption. An analysis of the results allows us to assess changes of the overall adsorption charge density as well as that associated with the UPD H or anion adsorption. Theoretical treatment of the data leads us to examination, for the first time, of the thermodynamics of the UPD H on Pt(111) and to determination of the Pt(111)-HUPD surface bond energy. The results showed that, on the thermodynamic ground, HUPD is equivalent to Hchem since the respective bond energies are the same. Proximity of the bond energies leads to the conclusion that the species should occupy the same surface adsorption site. In the second part of the presentation, I present a methodology of preparing an ultra-thin layers of Schem on Pt(111), examine their chemical and electronic structure. Consequently, I discuss thermodynamics of UPD H on Pt(111) in presence of well-defined submonolayer of Schem. The results show that UPD H on t(111)-Schem follows a new adsorption isotherm. In concluding remarks, I will present new research pathways that can be pursued via surface electrochemistry.