Electrolyte effects on hydrogen evolution and solution resistance in microbial electrolysis cells

Matthew D. Merrill, Bruce Ernest Logan

Research output: Contribution to journalArticle

54 Citations (Scopus)

Abstract

Protonated weak acids commonly used in microbial electrolysis cell (MEC) solutions can affect the hydrogen evolution reaction (HER) through weak acid catalysis, and by lowering solution resistance between the anode and the cathode. Weak acid catalysis of the HER with protonated phosphate, acetate, and carbonate electrolyte species improved MEC performance by lowering the cathode's overpotential by up to 0.30 V at pH 5, compared to sodium chloride electrolytes. Deprotonation of weak acids into charged species at higher pHs improved MEC performance primarily by increasing the electrolyte's conductivity and therefore decreasing the solution resistance between electrodes. The potential contributions from weak acid catalysis and solution resistance were compared to determine whether a reactor would operate more efficiently at lower pH because of the HER, or at higher pH because of solution resistance. Phosphate and acetate electrolytes allowed the MEC to operate more efficiently under more acidic conditions (pH 5). Carbonate electrolytes increased performance from pH 5 to 9 due to a relatively large increases in conductivity. These results demonstrate that specific buffers can substantially contribute to MEC performance through both reduction in cathode overpotential and solution resistance.

Original languageEnglish (US)
Pages (from-to)203-208
Number of pages6
JournalJournal of Power Sources
Volume191
Issue number2
DOIs
StatePublished - Jun 15 2009

Fingerprint

Regenerative fuel cells
electrolysis
Electrolytes
Hydrogen
electrolytes
hydrogen
acids
cells
Acids
Catalysis
catalysis
Cathodes
cathodes
Carbonates
acetates
carbonates
phosphates
Phosphates
Acetates
conductivity

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering
  • Energy Engineering and Power Technology
  • Renewable Energy, Sustainability and the Environment
  • Physical and Theoretical Chemistry

Cite this

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Electrolyte effects on hydrogen evolution and solution resistance in microbial electrolysis cells. / Merrill, Matthew D.; Logan, Bruce Ernest.

In: Journal of Power Sources, Vol. 191, No. 2, 15.06.2009, p. 203-208.

Research output: Contribution to journalArticle

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AU - Logan, Bruce Ernest

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AB - Protonated weak acids commonly used in microbial electrolysis cell (MEC) solutions can affect the hydrogen evolution reaction (HER) through weak acid catalysis, and by lowering solution resistance between the anode and the cathode. Weak acid catalysis of the HER with protonated phosphate, acetate, and carbonate electrolyte species improved MEC performance by lowering the cathode's overpotential by up to 0.30 V at pH 5, compared to sodium chloride electrolytes. Deprotonation of weak acids into charged species at higher pHs improved MEC performance primarily by increasing the electrolyte's conductivity and therefore decreasing the solution resistance between electrodes. The potential contributions from weak acid catalysis and solution resistance were compared to determine whether a reactor would operate more efficiently at lower pH because of the HER, or at higher pH because of solution resistance. Phosphate and acetate electrolytes allowed the MEC to operate more efficiently under more acidic conditions (pH 5). Carbonate electrolytes increased performance from pH 5 to 9 due to a relatively large increases in conductivity. These results demonstrate that specific buffers can substantially contribute to MEC performance through both reduction in cathode overpotential and solution resistance.

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