Created through a combination of soft chemistry gels and electrospinning - a technique where electrical force is applied to liquid to craft small fibers - the team constructed thin fiber-like strips of titanium dioxide (TiO2), a compound often utilized in solar cells, gas sensors and various self-cleaning technologies.
Despite being a great alternative energy source, solar fuel systems that utilize TiO2 nanoparticles are often power-limited because they can only undergo photocatalysis, or create chemical reactions, by absorbing non-visible UV light. This can cause significant challenges to implementation, including low efficiency and the need for complex filtration systems.
Yet when researchers added copper to the material to improve this process, their new structures, called nanomats, were able to absorb enough light energy to break down harmful pollutants in air and water, said Pelagia-Iren Gouma, lead author of the study and a professor of materials science and engineering at The Ohio State University.
"There hasn't been an easy way to create something like a blanket that you can lay on water and start creating energy," she said. "But we are the only ones who have made these structures and the only ones to demonstrate that they actually work."
When titanium dioxide absorbs light, electrons are formed that oxidize water and attack pollutants, slowly destroying them until they become benign. When copper is added, that process is supercharged, making it even more effective.
To determine this, researchers worked to characterize the nanomat's updated properties to understand how it behaved and what made it different from other self-cleaning nanoparticles, said Gouma. Surprisingly, researchers found that compared to traditional solar cells, these nanomats can be more successful at power generation when placed under natural sunlight, she said.
"These nanomats can be used as a power generator, or as water remediation tools," she said. "In both ways, you have a catalyst with the highest efficiency reported to date."
These lightweight, easy-to-remove fiber mats can float and operate atop any body of water and are even reusable through multiple cleaning cycles. Because nanomats are so effective, researchers envision that they could be used to rid water of industrial pollutants in developing countries, turning otherwise contaminated rivers and lakes into sources of clean drinking water.
Additionally, because this technology doesn't generate any toxic byproducts like some solar cell systems, nanomats are extremely environmentally friendly. "It's a safe material, it won't hurt anything, and it's as clean as it can be," said Gouma.
Still, although this team's technology is incredibly efficient, how long it will take to scale up commercially depends on how quickly industries take notice of the product. "We have the tools to make them in large quantities and translate them to various industries," said Gouma. "The only limitation is that it needs someone to take advantage of these abundant resources."
Overall, the study's findings suggest that nanomats could be a promising tool in many future photocatalytic applications, including long-term sustainability efforts like environmental remediation as well as solar-driven hydrogen production.
In the meantime, the team plans to examine ways to optimize the material further.
"This material is completely novel in terms of a new form of nanotechnology," said Gouma. "It's really impressive and something that we are very excited about."
Other Ohio State co-authors include Fateh Mikaeilia and Mohammad Mahafuzur Rahaman. This study was supported by the National Science Foundation.
Research Report:3D Self-Supported Visible Light Photochemical Nanocatalysts
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