Silver-Fed Bacteria In Fuel Cells
Microbial fuel cells are a promising but sadly not that much of a successful technology. But perhaps that is about to change. Their power will be substantially increased if the bacteria in them are fed with silver nanoparticles.
Image by analogicus from Pixabay
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Microbial fuel cells are a promising technology for advanced energetics. At least in theory. The problem is that current microbial fuel cells are not exactly effective. But now, experts from the University of California, Los Angeles (UCLA) found a way how to substantially improve them. They fed their bacterial inhabitants with silver nanoparticles making them much more electrically conductive.
Certain bacteria produce free electrons thanks to their metabolism. This is what is used by microbial fuel cells to create electricity. You just have the bacteria grow in biofilms of cell’s electrodes, give them some organic matter to feed and they will produce electricity. And as a bonus, clean water. But in the real world, the power output of these fuels cells is at the very least unconvincing.
A team from UCLA decided to change this. They used a crowd favorite. Gammaproteobacteria called Shewanella oneidensis can reduce the ions of metals and is can handle environments with oxygen and without oxygen. It is one of the promising candidates for microbial fuel cells. In its case, the major limitation lies in the permeability of the cellular membrane as the electrons cannot get easily through it.
Xiangfeng Duan and his colleagues decided to solve this by implanting conductive nanoparticles into the bacteria. First, they let the bacteria grow on graphene oxide enhanced with silver ions. The bacteria as they tend to do reduced the silver ions and incorporated them into themselves. They increased their electrical conductivity as well as the permeability of their cellular membrane for the electrons.
As Duan says, feeding the bacteria with silver nanoparticles is sort of like building speedways for the electrons. This will allow the bacteria to build more electrons at higher speeds for the microbial fuels cells. According to the researchers, the enhanced bacteria fed with silver generate 0.66 milliwatts per square centimeter of the electrode. That is by far the highest amount of power we got out of microbial fuel cells. This just might be the breakthrough bacteria were looking for.
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