Fast-Charging Hybrid Microbial Fuel Cell and CO2 Electrolyzer, Based on Formic Acid
Formic acid, which can be produced electrochemically from carbon
dioxide, is a promising energy carrier. A Chinese research team have now
developed a fast-charging hybrid battery system that combines the
electrochemical generation of formic acid as an energy carrier with a
microbial fuel cell. As the team demonstrate in the journal Angewandte Chemie,
this novel, fast-charging biohybrid battery system can be used to
monitor the toxicity of drinking water, just one of many potential
future applications.
© Wiley-VCH, re-use with credit to 'Angewandte Chemie' and a link to the original article.
Microbial fuel cells harness bacteria to generate electricity,
exploiting the ability of some bacterial species to convert energy-rich
molecules into electrical energy. In fully microbial batteries, bacteria
also produce the energy carrier molecules during the charging process,
which are then used to generate electricity during the discharging
process. However, one of the disadvantages of fully microbial batteries
is that charging is still rather inefficient and slow.
By coupling the purely inorganic electrochemical generation of a
biological active molecule with a microbial fuel cell, Yong Jiang's
research team at the Agriculture and Forestry University in Fuzhou,
China, and colleagues, have for the first time developed a two-stage
hybrid microbial battery system that overcomes many of the challenges
faced by fully microbial batteries.
The team also aimed to produce a biohybrid battery using simple and
inexpensive components to provide sustainable energy. They found that
formic acid is a sustainable biological energy carrier, because it can
be produced either biologically or electrocatalytically from carbon
dioxide and is then available for consumption by the bacteria in the
microbial fuel cell.
Using commercially available components, they designed an
electrolysis cell in which inorganic catalysts convert carbon dioxide
gas into formic acid. Using this design, the team found that the
charging process takes place within a few minutes. Once formic acid has
been produced and extracted from the electrolyte, it is fed into a
second device—the microbial fuel cell—where bacteria slowly convert it
into carbon dioxide and electricity at the bioanode.
This two-stage system produced enough current for 25 hours of
discharge, a value that is very useful in many applications. As a proof
of concept, the team used the discharge current produced to monitor
water for toxins and found that the current signal changed when
environmental toxins such as formaldehyde and copper were added to the
water. The team suggest further applications in sustainable wastewater
treatment or desalination.
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About the Author
Yong Jiang is a
professor of environmental engineering at Fujian Agriculture and
Forestry University, Fuzhou, China. His team explores microbial
electrochemical resource recovery from wastewater.
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