X-ray scattering study of Tl adlayers on the Au(111) electrode in alkaline solutions. Metal monolayer, OH[sup [minus]] coadsorption, and oxide formation

Journal Article · Thu Jul 21 04:00:00 EDT 1994 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100080a014· OSTI ID:7126053

Wang, J X; Adzic, R R; Ocko, B M ^[1]

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1. Brookhaven National Lab., Upton, NY (United States)

The structure of electrodeposited Tl adlayers on Au(111) in 0.1 M NaOH has been investigated using surface X-ray scattering. Incommensurate, hexagonal Tl structures exist over a wide potential region positive of bulk deposition. In the potential region between -0.66 and -0.38 V (versus Ag/AgCl), the Tl monolayer is rotated from the substrate axes by 5.2[degree]-6.2[degrees] and is closely packed with a Tl-Tl separation ranging from 3.34 to 3.43 [angstrom]. Between [minus]0.36 and -0.18 V, an incommensurate, aligned-hexagonal phase is observed in which the Tl-Tl spacing increases with increasing potential from 3.88 to 4.10 [angstrom]. The first-order transformation between these two phases at -0.37 V involves the coadsorption of OH[sup [minus]]. For the aligned-hexagonal phase the electrosorption valence is larger than unity, which indicates that partially-charged hydroxyl species are coadsorbed. The coadsorption of OH[sup [minus]] facilitates the existence of this unusual low-coverage, incommensurate Tl phase. At more positive potentials, the hexagonal adlayer lattice continuously rotates away from the substrate axes. At E > -0.04 V the adlayer appears disordered, and a two Tl atom thick Tl[sub 2]O adlayer forms. 26 refs., 12 figs., 1 tab.

• DOE Contract Number: AC02-76CH00016
• OSTI ID: 7126053
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 98:29; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102 -- Chemical & Spectral Procedures
400400* -- Electrochemistry
99 GENERAL AND MISCELLANEOUS
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ADSORPTION
ALKALI METAL COMPOUNDS
DEPOSITION
ELECTRODEPOSITION
ELECTRODES
ELECTROLYSIS
ELECTROMAGNETIC RADIATION
ELEMENTS
GOLD
HYDROGEN COMPOUNDS
HYDROXIDES
IONIZING RADIATIONS
LYSIS
MATHEMATICAL MODELS
METALS
OXYGEN COMPOUNDS
PHASE STUDIES
RADIATIONS
SCATTERING
SODIUM COMPOUNDS
SODIUM HYDROXIDES
SORPTION
SURFACE COATING
THALLIUM
TRANSITION ELEMENTS
VOLTAMETRY
X RADIATION