Electrochemical Characterization of Surface-Bound Redox Polymers Derived from 1,1'-Bis[((3- (triethoxysily 1)propyl)amino)carbonyl]cobaltocenium: Charge Transport, Anion Binding, and Use in Photoelectrochemical Hydrogen Generation

Richard A. Simon, Thomas E. Mallouk, Karen A. Daube, Mark S. Wrighton

Research output: Contribution to journalArticle

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Abstract

This paper describes the behavior of electrode-bound redox material derived from the hydrolysis of the -Si(OEt)3 groups of l,l'-bis[((3-(triethoxysilyl)propyl)amino)carbonyl]cobaltocenium (I). Surfaces of the conventional electrodes SnO2 and Pt derivatized with I have a reversible electrochemical response in H2O/electrolyte; the E°' is pH independent at -0.62 V vs. SCE. The photoelectrochemical behavior of p-type Si photocathodes derivatized with I reveals that the photoreduction of the cobaltocenium derivative can be effected at an electrode potential ~500 mV more positive than on metallic electrodes, consistent with the known behavior of p-type Si photocathodes. When polymer from I is deposited on p-type Si and subsequently coated with a small amount of Rh or Pd (~10-7 mol/cm2), the photoelectrochemical generation of H2 is possible with 632.8-nm (~15 mW/cm2) radiation and efficiencies in the vicinity of 2%. The polymer derived from I is more optically transparent and more durable at negative potentials than redox polymers derived from viologen monomers. Potential-step measurements and steady-state-current measurements for mediated redox processes show that the charge-transport rate for the polymer derived from I is about the same as for polymers from viologen monomers; As for other positively charged redox polymers, the material from I will electrostatically bind large transition-metal complex anions such as IrCl62+/3-, Fe(CN)6 3-/4-, and Mo(CN)8 3-/4-. A quantitative study of the relative binding of Cl- and Fe(CN)63- has been done; ΔH° = +12 ± 0.5 kcal/mol, and ΔS° = +52 ± 2 cal/(mol K). Thus, entropy drives the displacement of Cl- by Fe(CN)63-. The redox potential of the Fe(CN)6 3-/4- system is approximately 50 mV more negative in the polymer compared to the solution potential.

Original languageEnglish (US)
Pages (from-to)3119-3126
Number of pages8
JournalInorganic Chemistry
Volume24
Issue number20
DOIs
StatePublished - Sep 1 1985

Fingerprint

Anions
Charge transfer
Hydrogen
Polymers
anions
polymers
hydrogen
Viologens
Electrodes
Photocathodes
electrodes
photocathodes
monomers
Monomers
Coordination Complexes
Electric current measurement
Oxidation-Reduction
photochemical reactions
Electrolytes
Transition metals

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

Cite this

@article{96b24bc876f145adb907088b49a76074,
title = "Electrochemical Characterization of Surface-Bound Redox Polymers Derived from 1,1'-Bis[((3- (triethoxysily 1)propyl)amino)carbonyl]cobaltocenium: Charge Transport, Anion Binding, and Use in Photoelectrochemical Hydrogen Generation",
abstract = "This paper describes the behavior of electrode-bound redox material derived from the hydrolysis of the -Si(OEt)3 groups of l,l'-bis[((3-(triethoxysilyl)propyl)amino)carbonyl]cobaltocenium (I). Surfaces of the conventional electrodes SnO2 and Pt derivatized with I have a reversible electrochemical response in H2O/electrolyte; the E°' is pH independent at -0.62 V vs. SCE. The photoelectrochemical behavior of p-type Si photocathodes derivatized with I reveals that the photoreduction of the cobaltocenium derivative can be effected at an electrode potential ~500 mV more positive than on metallic electrodes, consistent with the known behavior of p-type Si photocathodes. When polymer from I is deposited on p-type Si and subsequently coated with a small amount of Rh or Pd (~10-7 mol/cm2), the photoelectrochemical generation of H2 is possible with 632.8-nm (~15 mW/cm2) radiation and efficiencies in the vicinity of 2{\%}. The polymer derived from I is more optically transparent and more durable at negative potentials than redox polymers derived from viologen monomers. Potential-step measurements and steady-state-current measurements for mediated redox processes show that the charge-transport rate for the polymer derived from I is about the same as for polymers from viologen monomers; As for other positively charged redox polymers, the material from I will electrostatically bind large transition-metal complex anions such as IrCl62+/3-, Fe(CN)6 3-/4-, and Mo(CN)8 3-/4-. A quantitative study of the relative binding of Cl- and Fe(CN)63- has been done; ΔH° = +12 ± 0.5 kcal/mol, and ΔS° = +52 ± 2 cal/(mol K). Thus, entropy drives the displacement of Cl- by Fe(CN)63-. The redox potential of the Fe(CN)6 3-/4- system is approximately 50 mV more negative in the polymer compared to the solution potential.",
author = "Simon, {Richard A.} and Mallouk, {Thomas E.} and Daube, {Karen A.} and Wrighton, {Mark S.}",
year = "1985",
month = "9",
day = "1",
doi = "10.1021/ic00214a008",
language = "English (US)",
volume = "24",
pages = "3119--3126",
journal = "Inorganic Chemistry",
issn = "0020-1669",
publisher = "American Chemical Society",
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}

Electrochemical Characterization of Surface-Bound Redox Polymers Derived from 1,1'-Bis[((3- (triethoxysily 1)propyl)amino)carbonyl]cobaltocenium : Charge Transport, Anion Binding, and Use in Photoelectrochemical Hydrogen Generation. / Simon, Richard A.; Mallouk, Thomas E.; Daube, Karen A.; Wrighton, Mark S.

In: Inorganic Chemistry, Vol. 24, No. 20, 01.09.1985, p. 3119-3126.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Electrochemical Characterization of Surface-Bound Redox Polymers Derived from 1,1'-Bis[((3- (triethoxysily 1)propyl)amino)carbonyl]cobaltocenium

T2 - Charge Transport, Anion Binding, and Use in Photoelectrochemical Hydrogen Generation

AU - Simon, Richard A.

AU - Mallouk, Thomas E.

AU - Daube, Karen A.

AU - Wrighton, Mark S.

PY - 1985/9/1

Y1 - 1985/9/1

N2 - This paper describes the behavior of electrode-bound redox material derived from the hydrolysis of the -Si(OEt)3 groups of l,l'-bis[((3-(triethoxysilyl)propyl)amino)carbonyl]cobaltocenium (I). Surfaces of the conventional electrodes SnO2 and Pt derivatized with I have a reversible electrochemical response in H2O/electrolyte; the E°' is pH independent at -0.62 V vs. SCE. The photoelectrochemical behavior of p-type Si photocathodes derivatized with I reveals that the photoreduction of the cobaltocenium derivative can be effected at an electrode potential ~500 mV more positive than on metallic electrodes, consistent with the known behavior of p-type Si photocathodes. When polymer from I is deposited on p-type Si and subsequently coated with a small amount of Rh or Pd (~10-7 mol/cm2), the photoelectrochemical generation of H2 is possible with 632.8-nm (~15 mW/cm2) radiation and efficiencies in the vicinity of 2%. The polymer derived from I is more optically transparent and more durable at negative potentials than redox polymers derived from viologen monomers. Potential-step measurements and steady-state-current measurements for mediated redox processes show that the charge-transport rate for the polymer derived from I is about the same as for polymers from viologen monomers; As for other positively charged redox polymers, the material from I will electrostatically bind large transition-metal complex anions such as IrCl62+/3-, Fe(CN)6 3-/4-, and Mo(CN)8 3-/4-. A quantitative study of the relative binding of Cl- and Fe(CN)63- has been done; ΔH° = +12 ± 0.5 kcal/mol, and ΔS° = +52 ± 2 cal/(mol K). Thus, entropy drives the displacement of Cl- by Fe(CN)63-. The redox potential of the Fe(CN)6 3-/4- system is approximately 50 mV more negative in the polymer compared to the solution potential.

AB - This paper describes the behavior of electrode-bound redox material derived from the hydrolysis of the -Si(OEt)3 groups of l,l'-bis[((3-(triethoxysilyl)propyl)amino)carbonyl]cobaltocenium (I). Surfaces of the conventional electrodes SnO2 and Pt derivatized with I have a reversible electrochemical response in H2O/electrolyte; the E°' is pH independent at -0.62 V vs. SCE. The photoelectrochemical behavior of p-type Si photocathodes derivatized with I reveals that the photoreduction of the cobaltocenium derivative can be effected at an electrode potential ~500 mV more positive than on metallic electrodes, consistent with the known behavior of p-type Si photocathodes. When polymer from I is deposited on p-type Si and subsequently coated with a small amount of Rh or Pd (~10-7 mol/cm2), the photoelectrochemical generation of H2 is possible with 632.8-nm (~15 mW/cm2) radiation and efficiencies in the vicinity of 2%. The polymer derived from I is more optically transparent and more durable at negative potentials than redox polymers derived from viologen monomers. Potential-step measurements and steady-state-current measurements for mediated redox processes show that the charge-transport rate for the polymer derived from I is about the same as for polymers from viologen monomers; As for other positively charged redox polymers, the material from I will electrostatically bind large transition-metal complex anions such as IrCl62+/3-, Fe(CN)6 3-/4-, and Mo(CN)8 3-/4-. A quantitative study of the relative binding of Cl- and Fe(CN)63- has been done; ΔH° = +12 ± 0.5 kcal/mol, and ΔS° = +52 ± 2 cal/(mol K). Thus, entropy drives the displacement of Cl- by Fe(CN)63-. The redox potential of the Fe(CN)6 3-/4- system is approximately 50 mV more negative in the polymer compared to the solution potential.

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