Normalized differential reflectance spectroscopy at polycrystalline platinum electrodes in aqueous acidic electrolytes

Quantitative aspects

Ping Shi, Iosif Fromondi, Daniel Alberto Scherson

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

The intensity of monochromatic light (λ = 633 nm) reflected off the surface of a polycrystalline Pt electrode, R, has been measured in situ as a function of potential, E, during continuous voltammetric cycles in the range -0.25 < E < 1.05 V vs. SCE, both in 0.5 M HClO 4 and 0.5 M H 2SO 4 aqueous solutions. Plots of the normalized differential reflectance, ΔR/R = [R(E sam) - R(E ref)] / R(E ref) vs. Q n, where E sam and E ref refer to the sampling and reference potentials, respectively, and Q n is the coulometrically determined relative oxide charge (in terms of e/Pt surface atom), were found to deviate from linearity in the PtOH formation region. Improved proportionality between ΔR/R and Q n was achieved up to Q n = 1, upon correcting ΔR/R for double layer effects using the method originally reported by Conway et al. [3]. In the case of 0.5 M H 2SO 4, however, remaining discrepancies could only be resolved by accounting for the charge due to bisulfate desorption induced by PtOH formation on the surface. On the basis of these results, it has been concluded that for both types of electrolytes, ΔR/R is proportional to the PtOH coverage, θ, and independent of the applied potential for Q n ≤ 1, opening new prospects for monitoring θ quantitatively during the course of faradaic reactions.

Original languageEnglish
Pages (from-to)1307-1318
Number of pages12
JournalZeitschrift fur Physikalische Chemie
Volume221
Issue number9-10
DOIs
Publication statusPublished - 2007 Oct 30
Externally publishedYes

Fingerprint

Platinum
Electrolytes
platinum
electrolytes
Spectroscopy
reflectance
Electrodes
electrodes
spectroscopy
Oxides
linearity
Desorption
plots
desorption
sampling
Sampling
aqueous solutions
Atoms
cycles
oxides

Keywords

  • Adsorption
  • In situ methods
  • Oxide formation
  • Platinum
  • Reflectance spectroscopy

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Atomic and Molecular Physics, and Optics

Cite this

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title = "Normalized differential reflectance spectroscopy at polycrystalline platinum electrodes in aqueous acidic electrolytes: Quantitative aspects",
abstract = "The intensity of monochromatic light (λ = 633 nm) reflected off the surface of a polycrystalline Pt electrode, R, has been measured in situ as a function of potential, E, during continuous voltammetric cycles in the range -0.25 < E < 1.05 V vs. SCE, both in 0.5 M HClO 4 and 0.5 M H 2SO 4 aqueous solutions. Plots of the normalized differential reflectance, ΔR/R = [R(E sam) - R(E ref)] / R(E ref) vs. Q n, where E sam and E ref refer to the sampling and reference potentials, respectively, and Q n is the coulometrically determined relative oxide charge (in terms of e/Pt surface atom), were found to deviate from linearity in the PtOH formation region. Improved proportionality between ΔR/R and Q n was achieved up to Q n = 1, upon correcting ΔR/R for double layer effects using the method originally reported by Conway et al. [3]. In the case of 0.5 M H 2SO 4, however, remaining discrepancies could only be resolved by accounting for the charge due to bisulfate desorption induced by PtOH formation on the surface. On the basis of these results, it has been concluded that for both types of electrolytes, ΔR/R is proportional to the PtOH coverage, θ, and independent of the applied potential for Q n ≤ 1, opening new prospects for monitoring θ quantitatively during the course of faradaic reactions.",
keywords = "Adsorption, In situ methods, Oxide formation, Platinum, Reflectance spectroscopy",
author = "Ping Shi and Iosif Fromondi and Scherson, {Daniel Alberto}",
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T1 - Normalized differential reflectance spectroscopy at polycrystalline platinum electrodes in aqueous acidic electrolytes

T2 - Quantitative aspects

AU - Shi, Ping

AU - Fromondi, Iosif

AU - Scherson, Daniel Alberto

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N2 - The intensity of monochromatic light (λ = 633 nm) reflected off the surface of a polycrystalline Pt electrode, R, has been measured in situ as a function of potential, E, during continuous voltammetric cycles in the range -0.25 < E < 1.05 V vs. SCE, both in 0.5 M HClO 4 and 0.5 M H 2SO 4 aqueous solutions. Plots of the normalized differential reflectance, ΔR/R = [R(E sam) - R(E ref)] / R(E ref) vs. Q n, where E sam and E ref refer to the sampling and reference potentials, respectively, and Q n is the coulometrically determined relative oxide charge (in terms of e/Pt surface atom), were found to deviate from linearity in the PtOH formation region. Improved proportionality between ΔR/R and Q n was achieved up to Q n = 1, upon correcting ΔR/R for double layer effects using the method originally reported by Conway et al. [3]. In the case of 0.5 M H 2SO 4, however, remaining discrepancies could only be resolved by accounting for the charge due to bisulfate desorption induced by PtOH formation on the surface. On the basis of these results, it has been concluded that for both types of electrolytes, ΔR/R is proportional to the PtOH coverage, θ, and independent of the applied potential for Q n ≤ 1, opening new prospects for monitoring θ quantitatively during the course of faradaic reactions.

AB - The intensity of monochromatic light (λ = 633 nm) reflected off the surface of a polycrystalline Pt electrode, R, has been measured in situ as a function of potential, E, during continuous voltammetric cycles in the range -0.25 < E < 1.05 V vs. SCE, both in 0.5 M HClO 4 and 0.5 M H 2SO 4 aqueous solutions. Plots of the normalized differential reflectance, ΔR/R = [R(E sam) - R(E ref)] / R(E ref) vs. Q n, where E sam and E ref refer to the sampling and reference potentials, respectively, and Q n is the coulometrically determined relative oxide charge (in terms of e/Pt surface atom), were found to deviate from linearity in the PtOH formation region. Improved proportionality between ΔR/R and Q n was achieved up to Q n = 1, upon correcting ΔR/R for double layer effects using the method originally reported by Conway et al. [3]. In the case of 0.5 M H 2SO 4, however, remaining discrepancies could only be resolved by accounting for the charge due to bisulfate desorption induced by PtOH formation on the surface. On the basis of these results, it has been concluded that for both types of electrolytes, ΔR/R is proportional to the PtOH coverage, θ, and independent of the applied potential for Q n ≤ 1, opening new prospects for monitoring θ quantitatively during the course of faradaic reactions.

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KW - Reflectance spectroscopy

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