A scanning electron microscope image of carbon nanofibers coated with PEDOT. Image: Juan Guzman and Meryem Pehlivaner.
A scanning electron microscope image of carbon nanofibers coated with PEDOT. Image: Juan Guzman and Meryem Pehlivaner.

Materials scientists and bioelectrochemical engineers at Cornell University have created an innovative, cost-competitive electrode material for cleaning pollutants in wastewater.

The researchers created electro-spun carbon nanofiber electrodes and coated them with a conductive polymer called PEDOT, with the aim of competing with the carbon cloth electrodes that are currently available on the market. When the PEDOT coating is applied, an electrically active layer of the bacterium Geobacter sulfurreducens naturally grows on the electrode.

The conducting nanofibers create a favorable surface for these bacteria, which release electrons by digesting pollutants from the wastewater and then transfer these electrons to the electrode, thereby generating electricity. This research is reported in a paper in the Journal of Power Sources.

"Electrodes are expensive to make now, and this material could bring the price of electrodes way down, making it easier to clean up polluted water," said co-lead author Juan Guzman, a doctoral candidate in the field of biological and environmental engineering at Cornell. Under a microscope, the carbon nanofiber electrode resembles a kitchen scrubber.

The electrode was made by co-lead author Meryem Pehlivaner, currently a doctoral student at Northeastern University, with senior author Margaret Frey, professor of fiber science and an associate dean of the College of Human Ecology at Cornell. Pehlivaner fabricated the carbon nanofibers via electrospinning and carbonization processes. After a few hours electrospinning, a thick nanofiber sheet – visible to the naked eye – emerges.

Pehlivaner reached out to Guzman and senior author Lars Angenent, professor of biological and environmental engineering at Cornell, to collaborate on employing the carbon nanofiber electrodes for the simultaneous treatment of wastewater and production of electrical energy. The customizable carbon nanofiber electrode proved ideal for this application due to its high porosity, surface area and biocompatibility with the bacteria. Coating the nanofibers with PEDOT further improves their abilities, according to the researchers.

Guzman said that wastewater treatment plants do not employ this novel treatment method – yet. On a large scale, the bacteria at the electrode could capture and degrade pollutants from the wastewater that flows by it. Such a technology can improve wastewater treatment by allowing systems to take up less land and increase throughput.

Concepts like this happen on campuses where faculty and students want to communicate and collaborate, Angenent said. "This defines radical collaboration," he said. "We have fiber scientists talking to environmental engineers, from two very different Cornell colleges, to create reality from an idea – that was more or less a hunch – that will make cleaning wastewater better and a little more inexpensive."

This story is adapted from material from Cornell University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.