3D-Printed “Nano-Skyscrapers” Help Bacteria Convert Sunlight Into Electricity

University of Cambridge researchers used 3D printing to create lattices of high-rise “nano-enclosures” in which sun-loving bacteria can grow rapidly. Researchers were then able to extract the bacteria’s waste electrons left over from photosynthesis, which could be used to power small electronic devices. Photo credit: Gabriella Bocchetti

Researchers have built tiny “skyscrapers” for bacterial communities, helping them generate electricity using just sunlight and water.

The University of Cambridge researchers used 3D printing to create lattices of high-rise nanohousings in which sun-loving bacteria can grow rapidly. Researchers were then able to extract the bacteria’s waste electrons left over from photosynthesis, which could be used to power small electronic devices.

Other research teams have extracted energy from photosynthetic bacteria, but the Cambridge researchers found that providing the right kind of home increases the amount of energy they can extract by more than an order of magnitude. The approach is competitive with traditional renewable bioenergy production methods and has already achieved solar conversion efficiencies that can surpass many current biofuel production methods.

Their findings reported in the journal natural materialsopen new avenues in bioenergy production and suggest that “biohybrid” solar energy sources could be an important component in the carbon-free energy mix.

University of Cambridge researchers used 3D printing to create lattices of high-rise skyscrapers in which sun-loving bacteria can grow rapidly. Researchers were then able to extract the bacteria’s waste electrons left over from photosynthesis, which could be used to power small electronic devices. Photo credit: Gabriella Bocchetti

Current renewable technologies such as silicon-based solar cells and biofuels far outperform fossil fuels in terms of carbon emissions, but they also have limitations, such as: B. dependence on mining, challenges in recycling and dependence on agriculture and land use, leading to loss of biodiversity.

“Our approach is a step towards even more sustainable renewable energy devices for the future,” said Dr. Jenny Zhang from the Yusuf Hamied Department of Chemistry who led the research.

Zhang and her colleagues from the Department of Biochemistry and the Department of Materials Science and Metallurgy are working to rethink bioenergy into something that is sustainable and scalable.

Photosynthetic bacteria or cyanobacteria are the most abundant life form on earth. For several years, researchers have been trying to “rewire” the photosynthetic mechanisms of cyanobacteria to extract energy from them.

“There was a bottleneck in terms of how much energy you can actually harvest from photosynthetic systems, but no one understood where the bottleneck was,” Zhang said. “Most scientists assumed that the bottleneck on the biological side was bacteria, but we found that a major bottleneck is actually on the material side.”

Cyanobacteria need a lot of sunlight to grow – like the surface of a lake in summer. And to harvest the energy they produce through photosynthesis, the bacteria need to be attached to electrodes.

The Cambridge team 3D printed custom metal oxide nanoparticle electrodes tailored to work with the cyanobacteria in photosynthesis. The electrodes were printed as highly branched, densely packed columnar structures, like a tiny city.

Zhang’s team developed a printing technique that allows control over multiple length scales, making the structures highly customizable, which could benefit a variety of areas.

“The electrodes have excellent light-conducting properties, like a high-rise apartment with many windows,” Zhang said. “Cyanobacteria need something to attach themselves to and form a community with their neighbors. Our electrodes enable a balance between a lot of surface area and a lot of light – like a glass skyscraper.”

Once the self-assembling cyanobacteria were in their new “wired” home, the researchers found that they were more efficient than other current bioenergy technologies, such as biofuels. The technique increased the amount of energy extracted by more than an order of magnitude over other methods of producing bioenergy from photosynthesis.

“I was surprised that we were able to match the numbers we achieved – similar numbers have been predicted for many years, but this is the first time these numbers have been shown experimentally,” Zhang said. “Cyanobacteria are versatile chemical factories. Our approach allows us to get early into their energy conversion pathway, which helps us understand how they perform the energy conversion so we can leverage their natural pathways for renewable fuels or chemical generation.”

Reference: “3D Printed Hierarchical Column Array Electrodes for High-Performance Semi-Artificial Photosynthesis” March 7, 2022, natural materials.
DOI: 10.1038/s41563-022-01205-5

The research was supported in part by the Biotechnology and Biological Sciences Research Council, the Cambridge Trust, the Isaac Newton Trust and the European Research Council. Jenny Zhang is a BBSRC David Phillips Fellow in the Department of Chemistry and a Fellow at Corpus Christi College, Cambridge.