Adsorption of Bipyridyls and Structurally Related Compounds at Pt(lll) Electrodes: Studies by Vibrational Spectroscopy (EELS), Auger Spectroscopy, and Electrochemistry

Scott A. Chaffins, John Y. Gui, Chiu-Hsun Lin, Frank Lu, Donald A. Stern, Donald C. Zapien, Arthur T. Hubbard, Bruce E. Kahn, Ghaleb N. Salaita, C. Michael Elliott

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

The adsorption behavior of bipyridyls and structurally related compounds from solution at well-defined Pt(lll) surfaces is examined in this study to explore the influence of adsorbate molecular structure on surface bonding, molecular orientation, vibrational spectroscopy, acid-base reactivity, and electrochemical behavior of adsorbed aromatic molecules. Molecules were selected to represent various degrees of steric hindrance at the ring nitrogens: 2,2'-bipyridyl (22BPY), 2,4-bipyridyl (24BPY), 3,3'-bipyridyl (33BPY), 4,4'-bipyridyl (44BPY), 2-phenylpyridine (2PPY), 3-phenylpyridine (3PPY), 4-phenylpyridine (4PPY), 2,6-diphenylpyridine (26DPPY), 2-methylpyridine (2MPY), and 2,6-dimethylpyridine (26DMPY). A series of carboxylic acids was also studied in order to explore the interactions between acidic moieties and the Pt(lll) surface: 2,2'-biphenyldicarboxylic acid (22BPDC), 4,4'-biphenyldicarboxylic acid (44BPDC), 2,2'-bipyridyl-4,4'-dicarboxylic acid (44DC), 2,2'-bipyridyl-4-methyl-4'-carboxylic acid (4M4C), 2,2'-bipyridyl-5,5'-dicarboxylic acid (55DC), and 2,2'-bipyridyl-4,4',5,5'-tetracarboxylic acid (4455TC). Packing densities (moles adsorbed per unit area) were measured by means of Auger spectroscopy. Linear potential scan voltammetry was used to determine the reactivity of the adsorbed layers toward electrochemical oxidation; electrochemical reactivity of these compounds provides important clues to their mode of bonding to the surface. Surface vibrational spectra were obtained by electron energy-loss spectroscopy (EELS) and are assigned by comparison with the IR spectra of the pure compounds. The Pt(111) surfaces used in this study were characterized by LEED. Most of the subject compounds are adsorbed with the ring plane nearly perpendicular to the platinum surface; the exceptions are those prevented from doing so by steric constraints such as bulky substituents adjacent to the aromatic nitrogen atoms. All of the bipyridyl carboxylic acids studied adsorb strongly and have pendant carboxylic acid moieties that give vibrational spectra that are noticeably dependant on the electrode potential and that react readily with KOH. Adsorption at relatively positive potentials (+0.4 V vs Ag/AgCl) shows increased interaction of the carboxylic acid moieties with the metal surface compared with relatively negative potentials (-0.1 V vs Ag/AgCl), as evidenced by diminution of the intensities of bands due to O-H and C=O stretching, as well as shifts in the frequency and intensity of aromatic CC modes. The biphenyl carboxylic acids 22BPDC and 44BPDC allow the carboxylic acid to interact with the metal surface, even at relatively negative (-0.1 V vs Ag/AgCl) electrode potentials. This is borne out by low-intensity O-H and C=O stretching vibrations.

Original languageEnglish
Pages (from-to)957-970
Number of pages14
JournalLangmuir
Volume6
Issue number5
DOIs
Publication statusPublished - 1990 Jan 1

Fingerprint

Vibrational spectroscopy
2,2'-Dipyridyl
Electron energy loss spectroscopy
Electrochemistry
electrochemistry
carboxylic acids
Auger spectroscopy
Carboxylic acids
energy dissipation
Spectroscopy
electron energy
Carboxylic Acids
Adsorption
Electrodes
adsorption
electrodes
acids
Acids
spectroscopy
reactivity

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

Cite this

Chaffins, Scott A. ; Gui, John Y. ; Lin, Chiu-Hsun ; Lu, Frank ; Stern, Donald A. ; Zapien, Donald C. ; Hubbard, Arthur T. ; Kahn, Bruce E. ; Salaita, Ghaleb N. ; Elliott, C. Michael. / Adsorption of Bipyridyls and Structurally Related Compounds at Pt(lll) Electrodes : Studies by Vibrational Spectroscopy (EELS), Auger Spectroscopy, and Electrochemistry. In: Langmuir. 1990 ; Vol. 6, No. 5. pp. 957-970.
@article{7672591fa07c452fbbc5c6f079cabe66,
title = "Adsorption of Bipyridyls and Structurally Related Compounds at Pt(lll) Electrodes: Studies by Vibrational Spectroscopy (EELS), Auger Spectroscopy, and Electrochemistry",
abstract = "The adsorption behavior of bipyridyls and structurally related compounds from solution at well-defined Pt(lll) surfaces is examined in this study to explore the influence of adsorbate molecular structure on surface bonding, molecular orientation, vibrational spectroscopy, acid-base reactivity, and electrochemical behavior of adsorbed aromatic molecules. Molecules were selected to represent various degrees of steric hindrance at the ring nitrogens: 2,2'-bipyridyl (22BPY), 2,4-bipyridyl (24BPY), 3,3'-bipyridyl (33BPY), 4,4'-bipyridyl (44BPY), 2-phenylpyridine (2PPY), 3-phenylpyridine (3PPY), 4-phenylpyridine (4PPY), 2,6-diphenylpyridine (26DPPY), 2-methylpyridine (2MPY), and 2,6-dimethylpyridine (26DMPY). A series of carboxylic acids was also studied in order to explore the interactions between acidic moieties and the Pt(lll) surface: 2,2'-biphenyldicarboxylic acid (22BPDC), 4,4'-biphenyldicarboxylic acid (44BPDC), 2,2'-bipyridyl-4,4'-dicarboxylic acid (44DC), 2,2'-bipyridyl-4-methyl-4'-carboxylic acid (4M4C), 2,2'-bipyridyl-5,5'-dicarboxylic acid (55DC), and 2,2'-bipyridyl-4,4',5,5'-tetracarboxylic acid (4455TC). Packing densities (moles adsorbed per unit area) were measured by means of Auger spectroscopy. Linear potential scan voltammetry was used to determine the reactivity of the adsorbed layers toward electrochemical oxidation; electrochemical reactivity of these compounds provides important clues to their mode of bonding to the surface. Surface vibrational spectra were obtained by electron energy-loss spectroscopy (EELS) and are assigned by comparison with the IR spectra of the pure compounds. The Pt(111) surfaces used in this study were characterized by LEED. Most of the subject compounds are adsorbed with the ring plane nearly perpendicular to the platinum surface; the exceptions are those prevented from doing so by steric constraints such as bulky substituents adjacent to the aromatic nitrogen atoms. All of the bipyridyl carboxylic acids studied adsorb strongly and have pendant carboxylic acid moieties that give vibrational spectra that are noticeably dependant on the electrode potential and that react readily with KOH. Adsorption at relatively positive potentials (+0.4 V vs Ag/AgCl) shows increased interaction of the carboxylic acid moieties with the metal surface compared with relatively negative potentials (-0.1 V vs Ag/AgCl), as evidenced by diminution of the intensities of bands due to O-H and C=O stretching, as well as shifts in the frequency and intensity of aromatic CC modes. The biphenyl carboxylic acids 22BPDC and 44BPDC allow the carboxylic acid to interact with the metal surface, even at relatively negative (-0.1 V vs Ag/AgCl) electrode potentials. This is borne out by low-intensity O-H and C=O stretching vibrations.",
author = "Chaffins, {Scott A.} and Gui, {John Y.} and Chiu-Hsun Lin and Frank Lu and Stern, {Donald A.} and Zapien, {Donald C.} and Hubbard, {Arthur T.} and Kahn, {Bruce E.} and Salaita, {Ghaleb N.} and Elliott, {C. Michael}",
year = "1990",
month = "1",
day = "1",
doi = "10.1021/la00095a013",
language = "English",
volume = "6",
pages = "957--970",
journal = "Langmuir",
issn = "0743-7463",
publisher = "American Chemical Society",
number = "5",

}

Adsorption of Bipyridyls and Structurally Related Compounds at Pt(lll) Electrodes : Studies by Vibrational Spectroscopy (EELS), Auger Spectroscopy, and Electrochemistry. / Chaffins, Scott A.; Gui, John Y.; Lin, Chiu-Hsun; Lu, Frank; Stern, Donald A.; Zapien, Donald C.; Hubbard, Arthur T.; Kahn, Bruce E.; Salaita, Ghaleb N.; Elliott, C. Michael.

In: Langmuir, Vol. 6, No. 5, 01.01.1990, p. 957-970.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Adsorption of Bipyridyls and Structurally Related Compounds at Pt(lll) Electrodes

T2 - Studies by Vibrational Spectroscopy (EELS), Auger Spectroscopy, and Electrochemistry

AU - Chaffins, Scott A.

AU - Gui, John Y.

AU - Lin, Chiu-Hsun

AU - Lu, Frank

AU - Stern, Donald A.

AU - Zapien, Donald C.

AU - Hubbard, Arthur T.

AU - Kahn, Bruce E.

AU - Salaita, Ghaleb N.

AU - Elliott, C. Michael

PY - 1990/1/1

Y1 - 1990/1/1

N2 - The adsorption behavior of bipyridyls and structurally related compounds from solution at well-defined Pt(lll) surfaces is examined in this study to explore the influence of adsorbate molecular structure on surface bonding, molecular orientation, vibrational spectroscopy, acid-base reactivity, and electrochemical behavior of adsorbed aromatic molecules. Molecules were selected to represent various degrees of steric hindrance at the ring nitrogens: 2,2'-bipyridyl (22BPY), 2,4-bipyridyl (24BPY), 3,3'-bipyridyl (33BPY), 4,4'-bipyridyl (44BPY), 2-phenylpyridine (2PPY), 3-phenylpyridine (3PPY), 4-phenylpyridine (4PPY), 2,6-diphenylpyridine (26DPPY), 2-methylpyridine (2MPY), and 2,6-dimethylpyridine (26DMPY). A series of carboxylic acids was also studied in order to explore the interactions between acidic moieties and the Pt(lll) surface: 2,2'-biphenyldicarboxylic acid (22BPDC), 4,4'-biphenyldicarboxylic acid (44BPDC), 2,2'-bipyridyl-4,4'-dicarboxylic acid (44DC), 2,2'-bipyridyl-4-methyl-4'-carboxylic acid (4M4C), 2,2'-bipyridyl-5,5'-dicarboxylic acid (55DC), and 2,2'-bipyridyl-4,4',5,5'-tetracarboxylic acid (4455TC). Packing densities (moles adsorbed per unit area) were measured by means of Auger spectroscopy. Linear potential scan voltammetry was used to determine the reactivity of the adsorbed layers toward electrochemical oxidation; electrochemical reactivity of these compounds provides important clues to their mode of bonding to the surface. Surface vibrational spectra were obtained by electron energy-loss spectroscopy (EELS) and are assigned by comparison with the IR spectra of the pure compounds. The Pt(111) surfaces used in this study were characterized by LEED. Most of the subject compounds are adsorbed with the ring plane nearly perpendicular to the platinum surface; the exceptions are those prevented from doing so by steric constraints such as bulky substituents adjacent to the aromatic nitrogen atoms. All of the bipyridyl carboxylic acids studied adsorb strongly and have pendant carboxylic acid moieties that give vibrational spectra that are noticeably dependant on the electrode potential and that react readily with KOH. Adsorption at relatively positive potentials (+0.4 V vs Ag/AgCl) shows increased interaction of the carboxylic acid moieties with the metal surface compared with relatively negative potentials (-0.1 V vs Ag/AgCl), as evidenced by diminution of the intensities of bands due to O-H and C=O stretching, as well as shifts in the frequency and intensity of aromatic CC modes. The biphenyl carboxylic acids 22BPDC and 44BPDC allow the carboxylic acid to interact with the metal surface, even at relatively negative (-0.1 V vs Ag/AgCl) electrode potentials. This is borne out by low-intensity O-H and C=O stretching vibrations.

AB - The adsorption behavior of bipyridyls and structurally related compounds from solution at well-defined Pt(lll) surfaces is examined in this study to explore the influence of adsorbate molecular structure on surface bonding, molecular orientation, vibrational spectroscopy, acid-base reactivity, and electrochemical behavior of adsorbed aromatic molecules. Molecules were selected to represent various degrees of steric hindrance at the ring nitrogens: 2,2'-bipyridyl (22BPY), 2,4-bipyridyl (24BPY), 3,3'-bipyridyl (33BPY), 4,4'-bipyridyl (44BPY), 2-phenylpyridine (2PPY), 3-phenylpyridine (3PPY), 4-phenylpyridine (4PPY), 2,6-diphenylpyridine (26DPPY), 2-methylpyridine (2MPY), and 2,6-dimethylpyridine (26DMPY). A series of carboxylic acids was also studied in order to explore the interactions between acidic moieties and the Pt(lll) surface: 2,2'-biphenyldicarboxylic acid (22BPDC), 4,4'-biphenyldicarboxylic acid (44BPDC), 2,2'-bipyridyl-4,4'-dicarboxylic acid (44DC), 2,2'-bipyridyl-4-methyl-4'-carboxylic acid (4M4C), 2,2'-bipyridyl-5,5'-dicarboxylic acid (55DC), and 2,2'-bipyridyl-4,4',5,5'-tetracarboxylic acid (4455TC). Packing densities (moles adsorbed per unit area) were measured by means of Auger spectroscopy. Linear potential scan voltammetry was used to determine the reactivity of the adsorbed layers toward electrochemical oxidation; electrochemical reactivity of these compounds provides important clues to their mode of bonding to the surface. Surface vibrational spectra were obtained by electron energy-loss spectroscopy (EELS) and are assigned by comparison with the IR spectra of the pure compounds. The Pt(111) surfaces used in this study were characterized by LEED. Most of the subject compounds are adsorbed with the ring plane nearly perpendicular to the platinum surface; the exceptions are those prevented from doing so by steric constraints such as bulky substituents adjacent to the aromatic nitrogen atoms. All of the bipyridyl carboxylic acids studied adsorb strongly and have pendant carboxylic acid moieties that give vibrational spectra that are noticeably dependant on the electrode potential and that react readily with KOH. Adsorption at relatively positive potentials (+0.4 V vs Ag/AgCl) shows increased interaction of the carboxylic acid moieties with the metal surface compared with relatively negative potentials (-0.1 V vs Ag/AgCl), as evidenced by diminution of the intensities of bands due to O-H and C=O stretching, as well as shifts in the frequency and intensity of aromatic CC modes. The biphenyl carboxylic acids 22BPDC and 44BPDC allow the carboxylic acid to interact with the metal surface, even at relatively negative (-0.1 V vs Ag/AgCl) electrode potentials. This is borne out by low-intensity O-H and C=O stretching vibrations.

UR - http://www.scopus.com/inward/record.url?scp=0000353864&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0000353864&partnerID=8YFLogxK

U2 - 10.1021/la00095a013

DO - 10.1021/la00095a013

M3 - Article

AN - SCOPUS:0000353864

VL - 6

SP - 957

EP - 970

JO - Langmuir

JF - Langmuir

SN - 0743-7463

IS - 5

ER -