Surface dynamics at well-defined single crystal microfacetted Pt(111) electrodes: In situ optical studies

Iosif Fromondi, Daniel Alberto Scherson

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

The assembly and electrochemical oxidation of well-defined CO adlayers on Pt(111) microfacets in aqueous CO-saturated 0.1 M H2SO4 were examined by a combination of in situ, simultaneous, time-resolved, reflectance spectroscopy (RS) and second harmonic generation (SHG), and potential step and linear scan techniques. Optical transients were collected following potential steps from a value high enough for a full monolayer of bisulfate (θ = 0.2) to adsorb on the Pt(111) facet, Eox, to potentials Eads, at which either the c(2 x 2)-3CO or √19 × √19R23.4°-13CO phase is expected to form once surface saturation is achieved. Similar experiments involving subsequent steps from Eads to Eox provided unambiguous evidence that the rates of oxidation of c(2 x 2)-3CO on such quasi-perfect Pt(111) facet at constant overpotential are much slower than those of √19 × √19R23.4°-13CO, an effect attributed to the presence of intrinsic vacant sites within the latter, more dilute phase, which are required for oxidation of adsorbed CO to ensue. Furthermore, continuous CO adsorption-oxidation cycles were found to increase the rate of oxidation of the c(2 x 2)-3CO phase. This phenomenon was tentatively ascribed to the progressive emergence of defects along the edge of the facet (and/or within the facet itself) which serve as nucleation sites for the oxidation of adsorbed CO.

Original languageEnglish
Pages (from-to)59-68
Number of pages10
JournalFaraday Discussions
Volume140
DOIs
Publication statusPublished - 2008 Nov 5
Externally publishedYes

Fingerprint

Carbon Monoxide
Single crystals
Oxidation
oxidation
Electrodes
electrodes
flat surfaces
single crystals
Electrochemical oxidation
Harmonic generation
electrochemical oxidation
Monolayers
Nucleation
Spectroscopy
harmonic generations
Adsorption
assembly
Defects
nucleation
saturation

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Surface dynamics at well-defined single crystal microfacetted Pt(111) electrodes : In situ optical studies. / Fromondi, Iosif; Scherson, Daniel Alberto.

In: Faraday Discussions, Vol. 140, 05.11.2008, p. 59-68.

Research output: Contribution to journalArticle

@article{348f5e83ab0b4fbe895c111a0e8eed77,
title = "Surface dynamics at well-defined single crystal microfacetted Pt(111) electrodes: In situ optical studies",
abstract = "The assembly and electrochemical oxidation of well-defined CO adlayers on Pt(111) microfacets in aqueous CO-saturated 0.1 M H2SO4 were examined by a combination of in situ, simultaneous, time-resolved, reflectance spectroscopy (RS) and second harmonic generation (SHG), and potential step and linear scan techniques. Optical transients were collected following potential steps from a value high enough for a full monolayer of bisulfate (θ = 0.2) to adsorb on the Pt(111) facet, Eox, to potentials Eads, at which either the c(2 x 2)-3CO or √19 × √19R23.4°-13CO phase is expected to form once surface saturation is achieved. Similar experiments involving subsequent steps from Eads to Eox provided unambiguous evidence that the rates of oxidation of c(2 x 2)-3CO on such quasi-perfect Pt(111) facet at constant overpotential are much slower than those of √19 × √19R23.4°-13CO, an effect attributed to the presence of intrinsic vacant sites within the latter, more dilute phase, which are required for oxidation of adsorbed CO to ensue. Furthermore, continuous CO adsorption-oxidation cycles were found to increase the rate of oxidation of the c(2 x 2)-3CO phase. This phenomenon was tentatively ascribed to the progressive emergence of defects along the edge of the facet (and/or within the facet itself) which serve as nucleation sites for the oxidation of adsorbed CO.",
author = "Iosif Fromondi and Scherson, {Daniel Alberto}",
year = "2008",
month = "11",
day = "5",
doi = "10.1039/b805040f",
language = "English",
volume = "140",
pages = "59--68",
journal = "Faraday Discussions of the Chemical Society",
issn = "1364-5498",
publisher = "Royal Society of Chemistry",

}

TY - JOUR

T1 - Surface dynamics at well-defined single crystal microfacetted Pt(111) electrodes

T2 - In situ optical studies

AU - Fromondi, Iosif

AU - Scherson, Daniel Alberto

PY - 2008/11/5

Y1 - 2008/11/5

N2 - The assembly and electrochemical oxidation of well-defined CO adlayers on Pt(111) microfacets in aqueous CO-saturated 0.1 M H2SO4 were examined by a combination of in situ, simultaneous, time-resolved, reflectance spectroscopy (RS) and second harmonic generation (SHG), and potential step and linear scan techniques. Optical transients were collected following potential steps from a value high enough for a full monolayer of bisulfate (θ = 0.2) to adsorb on the Pt(111) facet, Eox, to potentials Eads, at which either the c(2 x 2)-3CO or √19 × √19R23.4°-13CO phase is expected to form once surface saturation is achieved. Similar experiments involving subsequent steps from Eads to Eox provided unambiguous evidence that the rates of oxidation of c(2 x 2)-3CO on such quasi-perfect Pt(111) facet at constant overpotential are much slower than those of √19 × √19R23.4°-13CO, an effect attributed to the presence of intrinsic vacant sites within the latter, more dilute phase, which are required for oxidation of adsorbed CO to ensue. Furthermore, continuous CO adsorption-oxidation cycles were found to increase the rate of oxidation of the c(2 x 2)-3CO phase. This phenomenon was tentatively ascribed to the progressive emergence of defects along the edge of the facet (and/or within the facet itself) which serve as nucleation sites for the oxidation of adsorbed CO.

AB - The assembly and electrochemical oxidation of well-defined CO adlayers on Pt(111) microfacets in aqueous CO-saturated 0.1 M H2SO4 were examined by a combination of in situ, simultaneous, time-resolved, reflectance spectroscopy (RS) and second harmonic generation (SHG), and potential step and linear scan techniques. Optical transients were collected following potential steps from a value high enough for a full monolayer of bisulfate (θ = 0.2) to adsorb on the Pt(111) facet, Eox, to potentials Eads, at which either the c(2 x 2)-3CO or √19 × √19R23.4°-13CO phase is expected to form once surface saturation is achieved. Similar experiments involving subsequent steps from Eads to Eox provided unambiguous evidence that the rates of oxidation of c(2 x 2)-3CO on such quasi-perfect Pt(111) facet at constant overpotential are much slower than those of √19 × √19R23.4°-13CO, an effect attributed to the presence of intrinsic vacant sites within the latter, more dilute phase, which are required for oxidation of adsorbed CO to ensue. Furthermore, continuous CO adsorption-oxidation cycles were found to increase the rate of oxidation of the c(2 x 2)-3CO phase. This phenomenon was tentatively ascribed to the progressive emergence of defects along the edge of the facet (and/or within the facet itself) which serve as nucleation sites for the oxidation of adsorbed CO.

UR - http://www.scopus.com/inward/record.url?scp=55049139999&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=55049139999&partnerID=8YFLogxK

U2 - 10.1039/b805040f

DO - 10.1039/b805040f

M3 - Article

C2 - 19213310

AN - SCOPUS:55049139999

VL - 140

SP - 59

EP - 68

JO - Faraday Discussions of the Chemical Society

JF - Faraday Discussions of the Chemical Society

SN - 1364-5498

ER -