Electrochemical reactivity of 2,2',5,5'-tetrahydroxybiphenyl and related compounds adsorbed at pt (111) surfaces: studies by eels, leed, auger spectroscopy and cyclic voltammetry

Ghaleb N. Salaita, Laarni Laguren-Davidson, Frank Lu, Nicholas Walton, Edna Wellner, Donald A. Stern, Nikola Batina, Douglas G. Frank, Chiu-Hsun Lin, Clifford S. Benton, Arthur T. Hubbard

Research output: Contribution to journalArticle

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Abstract

Adsorption and surface electrode reactions of a family of compounds containing the hydroquinone moiety, namely 2,2',5,5'-tetrahydroxybiphenyl (THBP), 2,5-dihydroxy-4-methylbenzylmercaptan (DMBM) and hydroquinone (HQ), have been studied at well-defined Pt (111) surfaces by means of cyclic voltammetry assisted by electron energy-loss spectroscopy (EELS), Auger electron spectroscopy and low-energy electron diffraction (LEED). Packing densities of THBP measured by Auger spectroscopy indicated adsorption predominantly with the rings parallel to the surface, although reversible electroactivity of the layer increased with increasing THBP concentration, indicating a small fraction of verticallyoriented molecules. In contrast, DMBM is adsorbed entirely through its sulfur atom with its ring perpendicular to the surface; the pendant 2,5-diphenyl moiety in adsorbed DMBM was reversibly electroactive. Adsorbed HQ was not reversibly electroactive at any adsorbate concentration. Vibrational spectra of the adsorbed species were obtained by means of EELS, and were compared with the infrared spectra of the parent compounds in KBr. EELS and IR spectra were closely similar except where adsorption changed the nature of the molecule: based upon virtual absence of the characteristic EELS O-H stretching band (near 3500 cm -1 ), the phenolic hydroxyl hydrogens of HQ and the horizontallyoriented form of THBP were removed upon adsorption, as was the mercaptan sulfhydryl hydrogen of DMBM. The EELS bands of polar groups such as OH are not broadened to the same extent as in the IR spectra of the solid compounds, evidently due to lesser intermolecular hydrogen bonding among such groups at the surface. LEED observations indicated that the THBP layer was structurally diffuse, while HQ formed a Pt (111) (3×3)-HQ adlattice and DMBM formed a Pt (111) (23 0.5 × 2 0.5 )R30 °-DMBM adlattice at packing densities slightly below saturation. Adsorbate orientation and mode of surface bonding exert a systematic influence on the product distribution of electrocatalytic oxidation of these well-characterized adsorbed organic intermediates, based upon cyclic voltammetry and potential-step chronocoulometry experiments. Also, these results have revealed that evacuation does not alter the composition or electrochemical properties of the chemisorbed layer formed from solution.

Original languageEnglish
Pages (from-to)253-273
Number of pages21
JournalJournal of Electroanalytical Chemistry
Volume245
Issue number1-2
DOIs
Publication statusPublished - 1988 Apr 25

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Electron energy loss spectroscopy
Cyclic voltammetry
Spectroscopy
Adsorption
Low energy electron diffraction
Adsorbates
Hydrogen
Molecules
Vibrational spectra
Auger electron spectroscopy
Electrochemical properties
Sulfur
Sulfhydryl Compounds
Hydroxyl Radical
Stretching
hydroquinone
Hydrogen bonds
Infrared radiation
Atoms
Oxidation

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry
  • Chemical Engineering(all)
  • Electrochemistry

Cite this

Salaita, Ghaleb N. ; Laguren-Davidson, Laarni ; Lu, Frank ; Walton, Nicholas ; Wellner, Edna ; Stern, Donald A. ; Batina, Nikola ; Frank, Douglas G. ; Lin, Chiu-Hsun ; Benton, Clifford S. ; Hubbard, Arthur T. / Electrochemical reactivity of 2,2',5,5'-tetrahydroxybiphenyl and related compounds adsorbed at pt (111) surfaces : studies by eels, leed, auger spectroscopy and cyclic voltammetry. In: Journal of Electroanalytical Chemistry. 1988 ; Vol. 245, No. 1-2. pp. 253-273.
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abstract = "Adsorption and surface electrode reactions of a family of compounds containing the hydroquinone moiety, namely 2,2',5,5'-tetrahydroxybiphenyl (THBP), 2,5-dihydroxy-4-methylbenzylmercaptan (DMBM) and hydroquinone (HQ), have been studied at well-defined Pt (111) surfaces by means of cyclic voltammetry assisted by electron energy-loss spectroscopy (EELS), Auger electron spectroscopy and low-energy electron diffraction (LEED). Packing densities of THBP measured by Auger spectroscopy indicated adsorption predominantly with the rings parallel to the surface, although reversible electroactivity of the layer increased with increasing THBP concentration, indicating a small fraction of verticallyoriented molecules. In contrast, DMBM is adsorbed entirely through its sulfur atom with its ring perpendicular to the surface; the pendant 2,5-diphenyl moiety in adsorbed DMBM was reversibly electroactive. Adsorbed HQ was not reversibly electroactive at any adsorbate concentration. Vibrational spectra of the adsorbed species were obtained by means of EELS, and were compared with the infrared spectra of the parent compounds in KBr. EELS and IR spectra were closely similar except where adsorption changed the nature of the molecule: based upon virtual absence of the characteristic EELS O-H stretching band (near 3500 cm -1 ), the phenolic hydroxyl hydrogens of HQ and the horizontallyoriented form of THBP were removed upon adsorption, as was the mercaptan sulfhydryl hydrogen of DMBM. The EELS bands of polar groups such as OH are not broadened to the same extent as in the IR spectra of the solid compounds, evidently due to lesser intermolecular hydrogen bonding among such groups at the surface. LEED observations indicated that the THBP layer was structurally diffuse, while HQ formed a Pt (111) (3×3)-HQ adlattice and DMBM formed a Pt (111) (23 0.5 × 2 0.5 )R30 °-DMBM adlattice at packing densities slightly below saturation. Adsorbate orientation and mode of surface bonding exert a systematic influence on the product distribution of electrocatalytic oxidation of these well-characterized adsorbed organic intermediates, based upon cyclic voltammetry and potential-step chronocoulometry experiments. Also, these results have revealed that evacuation does not alter the composition or electrochemical properties of the chemisorbed layer formed from solution.",
author = "Salaita, {Ghaleb N.} and Laarni Laguren-Davidson and Frank Lu and Nicholas Walton and Edna Wellner and Stern, {Donald A.} and Nikola Batina and Frank, {Douglas G.} and Chiu-Hsun Lin and Benton, {Clifford S.} and Hubbard, {Arthur T.}",
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Electrochemical reactivity of 2,2',5,5'-tetrahydroxybiphenyl and related compounds adsorbed at pt (111) surfaces : studies by eels, leed, auger spectroscopy and cyclic voltammetry. / Salaita, Ghaleb N.; Laguren-Davidson, Laarni; Lu, Frank; Walton, Nicholas; Wellner, Edna; Stern, Donald A.; Batina, Nikola; Frank, Douglas G.; Lin, Chiu-Hsun; Benton, Clifford S.; Hubbard, Arthur T.

In: Journal of Electroanalytical Chemistry, Vol. 245, No. 1-2, 25.04.1988, p. 253-273.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Electrochemical reactivity of 2,2',5,5'-tetrahydroxybiphenyl and related compounds adsorbed at pt (111) surfaces

T2 - studies by eels, leed, auger spectroscopy and cyclic voltammetry

AU - Salaita, Ghaleb N.

AU - Laguren-Davidson, Laarni

AU - Lu, Frank

AU - Walton, Nicholas

AU - Wellner, Edna

AU - Stern, Donald A.

AU - Batina, Nikola

AU - Frank, Douglas G.

AU - Lin, Chiu-Hsun

AU - Benton, Clifford S.

AU - Hubbard, Arthur T.

PY - 1988/4/25

Y1 - 1988/4/25

N2 - Adsorption and surface electrode reactions of a family of compounds containing the hydroquinone moiety, namely 2,2',5,5'-tetrahydroxybiphenyl (THBP), 2,5-dihydroxy-4-methylbenzylmercaptan (DMBM) and hydroquinone (HQ), have been studied at well-defined Pt (111) surfaces by means of cyclic voltammetry assisted by electron energy-loss spectroscopy (EELS), Auger electron spectroscopy and low-energy electron diffraction (LEED). Packing densities of THBP measured by Auger spectroscopy indicated adsorption predominantly with the rings parallel to the surface, although reversible electroactivity of the layer increased with increasing THBP concentration, indicating a small fraction of verticallyoriented molecules. In contrast, DMBM is adsorbed entirely through its sulfur atom with its ring perpendicular to the surface; the pendant 2,5-diphenyl moiety in adsorbed DMBM was reversibly electroactive. Adsorbed HQ was not reversibly electroactive at any adsorbate concentration. Vibrational spectra of the adsorbed species were obtained by means of EELS, and were compared with the infrared spectra of the parent compounds in KBr. EELS and IR spectra were closely similar except where adsorption changed the nature of the molecule: based upon virtual absence of the characteristic EELS O-H stretching band (near 3500 cm -1 ), the phenolic hydroxyl hydrogens of HQ and the horizontallyoriented form of THBP were removed upon adsorption, as was the mercaptan sulfhydryl hydrogen of DMBM. The EELS bands of polar groups such as OH are not broadened to the same extent as in the IR spectra of the solid compounds, evidently due to lesser intermolecular hydrogen bonding among such groups at the surface. LEED observations indicated that the THBP layer was structurally diffuse, while HQ formed a Pt (111) (3×3)-HQ adlattice and DMBM formed a Pt (111) (23 0.5 × 2 0.5 )R30 °-DMBM adlattice at packing densities slightly below saturation. Adsorbate orientation and mode of surface bonding exert a systematic influence on the product distribution of electrocatalytic oxidation of these well-characterized adsorbed organic intermediates, based upon cyclic voltammetry and potential-step chronocoulometry experiments. Also, these results have revealed that evacuation does not alter the composition or electrochemical properties of the chemisorbed layer formed from solution.

AB - Adsorption and surface electrode reactions of a family of compounds containing the hydroquinone moiety, namely 2,2',5,5'-tetrahydroxybiphenyl (THBP), 2,5-dihydroxy-4-methylbenzylmercaptan (DMBM) and hydroquinone (HQ), have been studied at well-defined Pt (111) surfaces by means of cyclic voltammetry assisted by electron energy-loss spectroscopy (EELS), Auger electron spectroscopy and low-energy electron diffraction (LEED). Packing densities of THBP measured by Auger spectroscopy indicated adsorption predominantly with the rings parallel to the surface, although reversible electroactivity of the layer increased with increasing THBP concentration, indicating a small fraction of verticallyoriented molecules. In contrast, DMBM is adsorbed entirely through its sulfur atom with its ring perpendicular to the surface; the pendant 2,5-diphenyl moiety in adsorbed DMBM was reversibly electroactive. Adsorbed HQ was not reversibly electroactive at any adsorbate concentration. Vibrational spectra of the adsorbed species were obtained by means of EELS, and were compared with the infrared spectra of the parent compounds in KBr. EELS and IR spectra were closely similar except where adsorption changed the nature of the molecule: based upon virtual absence of the characteristic EELS O-H stretching band (near 3500 cm -1 ), the phenolic hydroxyl hydrogens of HQ and the horizontallyoriented form of THBP were removed upon adsorption, as was the mercaptan sulfhydryl hydrogen of DMBM. The EELS bands of polar groups such as OH are not broadened to the same extent as in the IR spectra of the solid compounds, evidently due to lesser intermolecular hydrogen bonding among such groups at the surface. LEED observations indicated that the THBP layer was structurally diffuse, while HQ formed a Pt (111) (3×3)-HQ adlattice and DMBM formed a Pt (111) (23 0.5 × 2 0.5 )R30 °-DMBM adlattice at packing densities slightly below saturation. Adsorbate orientation and mode of surface bonding exert a systematic influence on the product distribution of electrocatalytic oxidation of these well-characterized adsorbed organic intermediates, based upon cyclic voltammetry and potential-step chronocoulometry experiments. Also, these results have revealed that evacuation does not alter the composition or electrochemical properties of the chemisorbed layer formed from solution.

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