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[en] Anionic adsorption on platinum and rhodium surfaces of different crystallographic orientations was studied by radioactive labelling technique and cyclic voltammetry. The free Gibbs energy of adsorption and the energy of lateral interaction of anions adsorbed on well-defined and disordered electrodes were calculated using the Bennes isotherm. It was shown that surface order generally leads to the increased amount of anions absorbed and affects substantially the potential dependence of adsorption. An electrocatalytic specificity of rhodium electrodes of different surface crystallography with respect of perchlorate reduction and chloride adsorption was found in a study performed on Rh(100), Rh(111) and polycrystalline Rh

[en] This paper describes the construction and performance of an argon detector with a high sensitivity towards hydrogen, carbon monoxide, methane and ethane. (C.F.)

[en] The adsorption and oxidation of methanol on platinized electrode with electrochemical and radiochemical methods has been determined in dependence on bulk concentration of methanol and electrode potential. Both methods simultaneously used allowed to elucidate the mechanism of adsorption and electrooxidation of methanol. (author)

[en] The effect of presence of DMSO in 0.5 M H₂SO₄ supporting electrolyte on adsorption and anodic oxidation of methanol (¹⁴C-labelled) on platinum has been studied by the use of radiochemical and electrochemical methods. The results indicate that DMSO actively interacts with platinum surface. The bulk concentration of DMSO as low as 10^-2 M prevents the methanol adsorption and the presence of DMSO has a great influence on the oxidation of methanol chemisorbed species. (S.B.)

[en] A radioelectrochemistry instrument has been constructed in order to characterize adsorbates on smooth electrodes, in situ. The instrument is described, and preliminary results are discussed. A smooth, polycrystalline electrode is pressed against a glass scintillator detector in order to reduce the solution background count rate to manageable levels. After the linearity of the system was confirmed by using NaH¹⁴CO₃ in solution, the kinetics of H¹⁴COOH adsorption and the potential dependence of [2,6-¹⁴C]pyridine adsorption were measured. At a bulk surfactant concentration of 10^-3 M, the sensitivity of this technique is about 1% of a monolayer. Adsorption kinetics of processes occurring on a time scale of seconds can be measured. This technique is expected to complement both in situ and ex situ surface electrochemistry spectroscopies

[en] Among catalytic electrode materials, platinum received the bulk of attention. To understand surface electrochemistry of platinum better, its pattern of behavior should be analyzed in the context of surface electrochemical properties of other metals. Rhodium appears to be the most straightforward material to meet this objective. The comparison of surface properties of well defined single crystal electrodes of the two metals, which display (111) and (100) crystallographic orientation, will be presented. Voltammetry, ultra-high vacuum LEED, Auger and in situ radiochemical measurements will be discussed and correlations between surface crystallography and electrochemical characteristics will be brought to focus

[en] Radiochemical measurements of adsorption on single crystal, well-defined electrodes are reported and the method of the measurements is described. Adsorption of acetic acid on Pt(111) surface was studied: the surface concentration data were correlated with voltammetric profiles of the Pt(111) electrode in perchloric acid electrolyte containing 0.5 mM of CH₃COOH. It is concluded that acetic acid adsorption is associative and occurs without a significant charge transfer across the interface. Instead, the recorded currents are due to adsorption/desorption processes of hydrogen, processes which are much better resolved on Pt(111) than on polycrystalline platinum. A classification of adsorption processes on catalytic electrodes and atmospheric methods of preparation of single crystal electrodes are discussed

[en] We studied deposition processes, adsorption, incorporation, and precipitation, of solute ions on the surface of aluminum and aluminum alloy 2024-T3 using electrochemical, radiochemical and ultra-high vacuum spectroscopic techniques. The measurements were carried out at open circuit potential and in the electrode potential range on the negative side of the open circuit potential (cathodic polarization conditions), at various pH. The focus was on sorption reversibility, the relationship between anion's surface concentration and pH, as well as on the effect of local reactions on ion deposition. We have found that ion deposition is primarily controlled by the solution pH on aluminum surfaces. The change in the alloy surface composition and morphology induced by the electrochemical treatment and ion deposition was monitored by scanning Auger microscopy and energy dispersive X-ray spectroscopy. We have found that both the solution pH and electrode polarization exhibit major influence on composition and stability of intermetallics as well as the ion surface coverage around these copper-rich centers. Specifically, the extent of ion deposition usually increased in the following order S-phase particle ≥ Cu-Fe-Al intermetallics > bulk matrix in acidic solutions. The most reactive parts of the A12024-T3 surface are the S-phase particles, which change their electrochemical character during solution exposure. (author)

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