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The rotating ring disk method is applied to examine the oxygen reduction reaction (ORR) on Ag single-crystal surfaces in alkaline solution over the temperature range 293-333 K. The oxygen reduction reaction proceeds as the serial 4e(super-) reaction pathway with a very small peroxide formation and the order of activity of Ag(hkl) in 0.1 M KOH has increased in the sequence (110) lesser than equal to (111) lesser than (100).

The effects of pH on the surface reconstruction of Au(100), on CO oxidation, and on the oxygen reduction reaction (ORR) are discussed by a combination of SXS, FTIR spectroscopy, and RRDE measurements. It is proposed that the pH-dependent kinetics of the ORR on Au(100) can be unraveled by finding the relationship between kinetic rates.

The particle size effect on the formation of OH adlayer, the CO bulk oxidation, and the oxygen reduction reaction (ORR) is studied on Pt nanoparticles in perchloric acid electrolyte. The potential of total zero charge that shifts approximately 35 mV negative by decreasing the particle size from 30 nm down to 1 nm is yielded.

A combination of electrochemical (EC) and surface X-ray scattering (SXS) measurements are used to study the surface reconstruction of Au(100) and the formation of a commensurate c(radic 2 x 22 radic 2)R45 degrees structure of the bromide (Br) adlayer. The role of adsorbed oxygenated species (OH(sub ad)) is established by monitoring the microscopic interface structures of Br(sub ad) during the consumption of OH(sub ad) in an electrochemical reaction in which strongly adsorbed OH(sub ad) is removed from the surface by a relatively weak adsorbed reactant, CO(sub ad).

Abstract: Bimetallic single crystals Pt3Sn(110) and Pt3Sn(111) have been characterized for in situ CO oxidation. Surface composition and structure were established in ultra high vacuum (UHV) by Auger electron spectroscopy, low energy ion scattering spectroscopy (LEISS) and low energy electron diffraction (LEED). LEED patterns of Pt3Sn(hkl) are consistent with the surface composition, determined by LEISS, of ∼25 or 50at.% Sn. Following UHV characterization crystals were transferred into the electrochemical environment where surface electrochemistry of adsorbed CO was studied in situ by infrared spectroscopy. Changes in band morphology and vibrational properties: splitting of the band and increase in the frequency mode, were found on Pt3Sn(hkl) and correlated to Pt(hkl) surfaces. Continuous oxidative removal of adsorbed CO starts as low as E<0.1V, which is an important property for CO-tolerant catalysts. In addition to electronic effects, other factors, such as surface structure and intermolecular repulsion between adsorbed species are responsible for high catalytic activity of Pt3Sn(hkl) alloys. [Copyright &y& Elsevier]