The formation of two Ag UPD layers on stepped Pt single crystal electrodes and their restructuring by co-adsorption of CO

Domke, Katrin F.; Xiao, Xiao-Yin; Baltruschat, Helmut

doi:10.1016/j.electacta.2009.03.088

Cited by 15 publications

(13 citation statements)

References 33 publications

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“…However, some attenuation of the remaining {111} peak is apparent and in fact the {111} site is blocked completely at 0.6 MLs. This behaviour is mostly in accordance with expectations based on differences in work function between silver and platinum [12,13,15] These have been noted previously [43,44] and in this case may be ascribed to partial filling of {110} sites by silver from measurements using Pt{332} electrodes [43,44]. There is also some intensity generated at potentials just positive of the {100} step site at 0.25 V as found for bismuth and this ''shift'' in the Pt{100} step peak when silver is adsorbed has also been seen with Pt single crystal electrode surfaces containing linear {100} 9 {111} steps [44].…”

Section: Metal Deposition At Pt{321}supporting

confidence: 84%

Electrooxidation of d- and l-Glucose at Well-Defined Chiral Bimetallic Electrodes

et al. 2011

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The electrooxidation of D-and L-glucose at chiral Pt{321} r/s single crystal electrodes modified with Au, Ag and Bi adatoms up to a coverage of one monolayer (ML) is reported. All adatoms investigated are found to selectively decorate kink and step sites. Only at higher coverages is adsorption onto the narrow {111} terrace sites observed for Bi, Ag and Au, consistent with previously reported adsorption behaviour on stepped surfaces vicinal to the {111} plane for chemisorbates exhibiting a lower work function than platinum. However, silver is found to block {111} terrace sites even when Pt step sites are still available on Pt{321}. This behaviour is ascribed to the propensity of silver to undergo place-exchange to form a surface alloy. The selective decoration of chiral kink sites has a profound influence on the voltammetric response of Pt{321} towards glucose electrooxidation. For bismuth adsorption, the electrooxidation current density initially increases and reaches a maximum when bismuth adsorption at {111} terraces commences. This is because the reaction pathways at step/kink sites leading to the formation of adsorbed CO (a surface poison for the clean surface reaction) and other strongly adsorbed intermediates, are either blocked by adsorbed bismuth or their electrooxidation and subsequent removal promoted. Once all step/kink sites are blocked by bismuth, hardly any chiral discrimination can be discerned between r-/s-electrodes towards D-/L-glucose. Silver adsorption does not cause any increase in glucose electrooxidation current density but rather induces a continual attenuation in glucose electrooxidation activity, particular (in contrast to bismuth) electrooxidation current at potentials in excess of 0.35 V. Therefore, unlike for bismuth, the initial glucose adsorption and electrooxidation processes associated with chiral kink sites appear to be preserved even though silver adsorbs at these sites. It is speculated that spontaneous place-exchange of silver with platinum to form a PtAg surface alloy at steps is responsible for this difference in behaviour between silver and bismuth. Finally, gold neither promotes reaction rate nor preserves chiral discrimination and is therefore deduced to act as an inert site blocker (no alloying, no promotion of CO electrooxidation) leading to complete attenuation of glucose electrooxidation current at a coverage of one ML.

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Section: Metal Deposition At Pt{321}supporting

confidence: 84%

Electrooxidation of d- and l-Glucose at Well-Defined Chiral Bimetallic Electrodes

et al. 2011

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“…The numerous publications concerned the formation mechanism of CO during the alcohol oxidation, the kinetics of CO on the electrode and the effect of the catalyst on the adsorption and oxidation of CO [55][56][57][58][59][60]. We performed the CO-stripping experiment to compare the performance of the Pt-WC/C(IMH)-T and traditional Pt/C electrocatalyst as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Preparation and performance of nanosized tungsten carbides for electrocatalysis

Shen

Yin

et al. 2010

Electrochimica Acta

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“…20 It has been shown that this procedure leads to surface topographies reasonably close to the nominal ones. [21][22][23] Tin deposition on the single crystal electrodes was carried out by cycling the electrode in solutions containing 10 À6 M SnSO 4 + 0.1 M H 2 SO 4 in a potential range between 0.05-0.9 V at a scan rate of 0.050 V s À1 . Under those circumstances, tin deposition is a diffusion controlled process that progresses in each potential cycle.…”

Section: Methodsmentioning

confidence: 99%

Electrochemical and spectroscopic studies of ethanol oxidation on Pt stepped surfaces modified by tin adatoms

Colle

Souza-Garcia

Tremiliosi‐Filho

et al. 2011

Phys. Chem. Chem. Phys.

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Ethanol oxidation on platinum stepped surfaces vicinal to the (111) pole modified by tin has been studied to determine the role of this adatom in the oxidation mechanism. Tin has been slowly deposited so that the initial stages of the deposition take place on the step, and deposition on the terrace only occurs when the step has been completely decorated. Voltammetric and chronoamperometric experiments demonstrate that tin on the step catalyzes the oxidation. The maximum enhancement is found when the step is completely decorated by tin. FTIR experiments using normal and isotopically labeled ethanol have been used to elucidate the effect of the tin adatoms in the mechanism. The obtained results indicate that the role of tin is double: (i) when the surface has sites capable of breaking the C-C bond of the molecule, that is, when the step sites are not completely covered by tin, it promotes the oxidation of CO formed from the molecular fragments to CO(2) through a bifunctional mechanism and (ii) it catalyzes the oxidation of ethanol to acetic acid.

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The formation of two Ag UPD layers on stepped Pt single crystal electrodes and their restructuring by co-adsorption of CO

Cited by 15 publications

References 33 publications

Electrooxidation of d- and l-Glucose at Well-Defined Chiral Bimetallic Electrodes

Electrooxidation of d- and l-Glucose at Well-Defined Chiral Bimetallic Electrodes

Preparation and performance of nanosized tungsten carbides for electrocatalysis

Electrochemical and spectroscopic studies of ethanol oxidation on Pt stepped surfaces modified by tin adatoms

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