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1993 Gewirth, Andrew A. Chen, Chun-Hsien 2014-12-17T21:29:06Z 2014-12-17T21:29:06Z 10000-01-01 1993 This thesis work has studied systems of Bi, Pb, Ag, and Hg underpotential deposition (UPD) on Au(111) electrodes. The application of the atomic force microscope (AFM), the scanning tunneling microscope (STM), and the surface x-ray scattering (SXS) to these UPD studies has provided in situ measurements from which we investigate factors that determine UPD surface structures and correlate these structures with surface reactivity. For all the UPD systems in this thesis work, atomic level features of the electrode surface have been revealed. In the case of Pb UPD, Pb starts to deposit by forming islands which exhibit a hexagonal close packed structure of Pb adatoms, while, in the other systems, the UPD adatoms form open lattices. In the Bi and Pb studies, we correlate the activities of the modified surface toward electroreduction of $\rm H\sb2O\sb2$ with the adlattice structures. A heterobimetallic bridge model for $\rm H\sb2O\sb2$ on the surface could explain the enhanced reactivity. The full monolayers of Bi and Hg, rhombohedral metals, form rectangular lattice structures on the hexagonal Au(111) surfaces. The partial charge retention on the Bi and Hg adatom opens the adlayer structure when the coverage is less than a full monolayer. The structure of the first submonolayers of Ag UPD is electrolyte-dependent. The electrode surface exhibits 3 x 3 and 4 x 4 overlayer structures in solutions containing sulfate and nitrate, respectively. In perchloric acid another open structure is observed and a close-packed monolayer is formed in acetic acid. The different monolayer structures give rise to packing densities which correlate with electrolyte size. This implies that the anions participate in reducing metal ions. Made available in DSpace on 2014-12-17T21:29:06Z (GMT). No. of bitstreams: 1 9328994.pdf: 6949527 bytes, checksum: 5dbf9b927507bf92a9c7c2f7bbdcb4d4 (MD5) Previous issue date: 1993 Embargo set by: Seth Robbins for item 72450 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs U of I Only 153 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1993. http://hdl.handle.net/2142/72282 (UMI)AAI9328994 Chemistry, Analytical Chemistry, Physical Physics, Condensed Matter In Situ Structural Study of Underpotential Deposition and Electrocatalysis on Gold(111) Electrodes text Chemistry Chemistry University of Illinois at Urbana-Champaign Dissertation Ph.D.