Researchers move forward in the development of microbial fuel cells

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• Source: University of California - Los Angeles


• Date: 18 Sep,2021

A UCLA-led group of engineers and chemists have taken an important step in the creation of fuel cells made by microbial organisms which is a method that makes use of natural bacteria to pull electrons out of organic material within the water to create electrical currents. A research paper detailing the groundbreaking technology was published recently in Science.

“Living systems for energy recovery that utilize the bacteria that are found in wastewater provide two-in-one solutions for environmental sustainability initiatives,” said co-corresponding author Yu Huang, a professor and chair of the Materials Science and Engineering Department at the UCLA Samueli School of Engineering. “The naturally occurring populations of bacteria are able to help clean up groundwater by degrading the harmful chemicals. The research we conducted offers a practical method to make use of renewable energy generated by these processes.”

The research team concentrated on the genus of bacteria Shewanella that has been extensively examined for their ability to generate energy. They can thrive in any type of environment which includes soil as well as seawater, wastewater, and soil regardless of the oxygen levels.

Shewanella organisms naturally reduce organic waste to smaller molecules with electrons becoming an end product of the metabolism process. When the bacteria develop as films on electrodes of the electrons may be taken in, creating an microbial fuel cell which generates electricity.

However the microbial fuel cells that are powered with Shewanella oneidensis have not yet attained enough currents from bacteria that they could be practical for industrial applications. The electrons aren’t moving fast enough to get past the membranes of the bacteria before entering the electrodes, thereby providing sufficient electricity and currents.

Adding the silver nanoparticles into the bacteria is like creating a dedicated express lane for electrons, which enabled us to extract more electrons and at faster speeds.”

Xiangfeng Duan, Study Corresponding Author and Professor of Chemistry and Biochemistry, University of California-Los Angeles

To tackle this issue, the researchers added silver nanoparticles to electrodes made of of graphene oxide. The silver nanoparticles release silver-ion ions that bacteria convert to silver nanoparticles with electrons produced by their metabolism and integrate to their cells. After being inside bacteria the silver particles function as tiny transmission wires collecting more electrons created by bacteria.

With significantly enhanced energy transfer efficiency for electrons, the Shewanellafilm that is silver-infused Shewanellafilm produces greater than 80 percent electrochemical electrons that are needed to power an electrical circuit producing the power in the range of 0.66 milliwatts/square centimeter. That’s more than double that of the previous benchmark for fuel cells based on microbial sources.

With the increase in power and efficiency this research, backed through the Office of Naval Research, demonstrated that fuel cells powered by silver Shewanella combination bacteria could pave the way to provide sufficient power in the real world.

Bocheng Cao, a UCLA doctoral student who is advised by Huang and Duan Huang, is the primary writer of the paper. The other UCLA senior authors include Gerard Wong, a professor of bioengineering; Paul Weiss, a UC Presidential Chair and a distinguished professor of biochemistry and chemistry Bioengineering, engineering and materials and Chong Liu who is the assistant professor for biochemistry and chemistry. Kenneth Nealson, a professor of earth sciences emeritus at USC is also an author in the senior category.

Duan, Huang, and Weiss are all part of the California NanoSystems Institute at UCLA.