Influence of mediator redox potential on fuel sensitivity of mediated laccase oxygen reduction electrodes

Deboleena Chakraborty, Scott Calabrese Barton

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Abstract

The impact of methanol on oxygen reduction activity is studied using a mediated biocathode catalyzed by laccase from Trametes versicolor. The sensitivity of oxygen reduction current density to the presence of methanol at such electrodes depends strongly on mediator redox potential. This study demonstrates that the selectivity of laccase cathodes toward oxygen reduction can allow methanol feed concentration up to 5 M in direct methanol fuel cells. Within the 0-5 M concentration range, methanol primarily affects enzyme kinetics and not the electron transport via the mediator. For methanol concentrations of 0-2.5 M, laccase activity toward oxygen was largely maintained; approximately 30 loss of activity occurred in the 2.5-5 M range, and irreversible loss of enzyme activity was observed beyond 7.5 M. The presence of methanol primarily decreases the turnover number of the enzyme rather than altering substrate binding, suggesting a noncompetitive inhibition mechanism. It is proposed that this reduction occurs due to changes in the electron transfer environment near the T1 binding pocket due to the presence of methanol.

LanguageEnglish (US)
JournalJournal of the Electrochemical Society
Volume158
Issue number4
DOIs
StatePublished - 2011

Profile

Laccase
Methanol
methyl alcohol
Oxygen
Electrodes
electrodes
sensitivity
oxygen
enzymes
Enzyme kinetics
Direct methanol fuel cells (DMFC)
Enzyme activity
enzyme activity
Oxidation-Reduction
Cathodes
Current density
fuel cells
Enzymes
electron transfer
cathodes

ASJC Scopus subject areas

  • Electrochemistry
  • Electronic, Optical and Magnetic Materials
  • Materials Chemistry
  • Surfaces, Coatings and Films
  • Renewable Energy, Sustainability and the Environment
  • Condensed Matter Physics

Cite this

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abstract = "The impact of methanol on oxygen reduction activity is studied using a mediated biocathode catalyzed by laccase from Trametes versicolor. The sensitivity of oxygen reduction current density to the presence of methanol at such electrodes depends strongly on mediator redox potential. This study demonstrates that the selectivity of laccase cathodes toward oxygen reduction can allow methanol feed concentration up to 5 M in direct methanol fuel cells. Within the 0-5 M concentration range, methanol primarily affects enzyme kinetics and not the electron transport via the mediator. For methanol concentrations of 0-2.5 M, laccase activity toward oxygen was largely maintained; approximately 30 loss of activity occurred in the 2.5-5 M range, and irreversible loss of enzyme activity was observed beyond 7.5 M. The presence of methanol primarily decreases the turnover number of the enzyme rather than altering substrate binding, suggesting a noncompetitive inhibition mechanism. It is proposed that this reduction occurs due to changes in the electron transfer environment near the T1 binding pocket due to the presence of methanol.",
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AU - Barton,Scott Calabrese

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N2 - The impact of methanol on oxygen reduction activity is studied using a mediated biocathode catalyzed by laccase from Trametes versicolor. The sensitivity of oxygen reduction current density to the presence of methanol at such electrodes depends strongly on mediator redox potential. This study demonstrates that the selectivity of laccase cathodes toward oxygen reduction can allow methanol feed concentration up to 5 M in direct methanol fuel cells. Within the 0-5 M concentration range, methanol primarily affects enzyme kinetics and not the electron transport via the mediator. For methanol concentrations of 0-2.5 M, laccase activity toward oxygen was largely maintained; approximately 30 loss of activity occurred in the 2.5-5 M range, and irreversible loss of enzyme activity was observed beyond 7.5 M. The presence of methanol primarily decreases the turnover number of the enzyme rather than altering substrate binding, suggesting a noncompetitive inhibition mechanism. It is proposed that this reduction occurs due to changes in the electron transfer environment near the T1 binding pocket due to the presence of methanol.

AB - The impact of methanol on oxygen reduction activity is studied using a mediated biocathode catalyzed by laccase from Trametes versicolor. The sensitivity of oxygen reduction current density to the presence of methanol at such electrodes depends strongly on mediator redox potential. This study demonstrates that the selectivity of laccase cathodes toward oxygen reduction can allow methanol feed concentration up to 5 M in direct methanol fuel cells. Within the 0-5 M concentration range, methanol primarily affects enzyme kinetics and not the electron transport via the mediator. For methanol concentrations of 0-2.5 M, laccase activity toward oxygen was largely maintained; approximately 30 loss of activity occurred in the 2.5-5 M range, and irreversible loss of enzyme activity was observed beyond 7.5 M. The presence of methanol primarily decreases the turnover number of the enzyme rather than altering substrate binding, suggesting a noncompetitive inhibition mechanism. It is proposed that this reduction occurs due to changes in the electron transfer environment near the T1 binding pocket due to the presence of methanol.

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