'Tiny Skyscraper’ Electrodes Raise Blue-Green Algae Bioenergy Output

Scientists have long researched photosynthetic bacteria's ability to convert sunlight, carbon dioxide, and water into energy, and a team has broken new ground in this field by providing these communities with a home that resembles a high-rise apartment building.

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These tiny grids of "nano-housing" provide the ideal environment for these bacteria to not only develop quickly, but also to maximize their energy-harvesting capacity.

Photosynthetic bacteria, often known as cyanobacteria or blue-green algae, can be found in all sorts of water, where they use sunshine to produce their own sustenance.

Their natural ability to do so has sparked a slew of promising renewable energy research projects, ranging from bionic mushrooms that generate electricity to algae-fueled bioreactors that absorb carbon dioxide to self-contained solutions that serve as a blueprint for commercial artificial photosynthesis systems.

Because cyanobacteria require a lot of sunlight to grow, they thrive in situations like lake surfaces, and a team at the University of Cambridge has made a breakthrough by experimenting with strategies to better meet these needs.

Another factor the researchers had to consider was that the bacteria needed to be linked to electrodes in order to collect any of the energy they produced through photosynthesis. The scientists are effectively aiming to kill two birds with one stone by designing electrodes that promote the growth of bacteria.

"There's been a limit in terms of how much energy you can actually harvest from photosynthetic systems," said Dr. Jenny Zhang, the study's lead author. "Most scientists assumed the bottleneck was on the biological side, in the bacteria, but we discovered a significant bottleneck on the material side."

The researchers employed 3D printing to create electrodes consisting of metal oxide nanoparticles that were organized in densely packed sets of pillars to resemble a miniature metropolis. The cyanobacteria thrived in this city, and they were able to create electricity with tremendous efficiency. The technique enhanced the amount of energy that can be harvested from cyanobacteria by "almost an order of magnitude," according to the researchers.

"I was amazed that we were able to obtain the results we did- comparable results had been predicted for many years, but this is the first time they have been demonstrated empirically," Zhang added.

"Cyanobacteria are chemical factories that may produce a wide range of products. Our method enables us to get into their energy conversion pathway early on, allowing us to better understand how they convert energy so that we may exploit their natural pathways for renewable fuel or chemical generation."

Another advantage of the method is that the printing technology can be tweaked to create structures of various heights and scales, allowing the miniature towns to be fitted to a variety of uses. The research not only demonstrates how energy from this type of photosynthesis may be better harnessed, but it also offers up new avenues for electrode design.

"Like a high-rise residence with lots of windows, the electrodes offer outstanding light-handling properties," Zhang added. "Cyanobacteria require a surface to cling to and create a community with their surroundings. Like a glass skyscraper, our electrodes allow for a balance between a large surface area and a large amount of light."

(Source: Blue Atlas)