Self-assembled peptides, when adjusted, show a great promise of electricity generation.
Nanogenerators capable of converting mechanical energy into electricity are typically made from metal oxides and lead-based perovskites. However, these inorganic materials are not biocompatible, so the race continues to create natural biocompatible piezoelectric materials for harvesting energy, electronic sensing and stimulating nerves and muscles.
University College Dublin and the University of Texas at Dallas, researchers decided to study peptide-based nanotubes because they would be an attractive option for use in electronic devices and for energy harvesting applications.
IN Journal of Applied Physics, from AIP Publishing, reports the group using a combination of ultraviolet and ozone exposure to generate a moisture difference and a field used to create horizontally aligned polarization of nanotubes on flexible substrates with interlocking electrodes.
“The piezoelectric properties of peptide-based materials make them particularly attractive for energy harvesting because pressing or bending them generates an electric charge,” said Sawsan Almohammed, lead author and postdoctoral researcher at University College Dublin.
There is also an increased need for organic materials to replace inorganic materials that tend to be toxic and difficult to manufacture.
“Peptide-based materials are organic, easy to manufacture and have strong chemical and physical stability,” she said.
In the group approach, the physical adaptation of nanotubes is achieved by patterning a moisture difference on the surface of a flexible substrate. This creates a chemical force that pushes the peptide nanotube solution from the hydrophobic region, which rejects water with a high contact angle to the hydrophilic region, which attracts water with a low contact angle.
Not only did the researchers improve the alignment of the pipes, which is important for energy harvesting applications, but they also improved the conductivity of the pipes by producing composite structures with graph oxide.
“It is well known that when two materials with different work functions come into contact with each other, an electric charge flows from low to high work function,” said Almohammed. “The most important novelty in our work is that controlling the horizontal alignment of the nanotubes using electric field and humidification-assisted self-assembly improved both current and voltage output, and further improvement was achieved by incorporating graphene oxide.”
The group’s work will enable the use of organic materials, especially peptide-based ones, more widely in electronic devices, sensors and energy harvesting applications, because two key limitations of peptide nanotubes – alignment and conductivity – have been improved.
“We are also investigating how charge transfer processes from bending and electric field applications can improve Raman spectroscopy – based detection of molecules,” Almohammed said. “We hope these two efforts can be combined to create a self-contained biosensor with a wide range of applications, including biological and environmental monitoring, high-contrast imaging and high-efficiency LEDs.”
Reference: “Energy Harvesting with Peptide Nanotubes – Graphene Oxide Flexible Substrates Made with Electric Field and Humidification Assisted Self-Assembly” by Sawsan Almohammed, Abi Thampi, Arwa Bazaid, Fengyuan Zhang, Salvador Moreno, Kevin Keogh, Majid Minary-Jolandan, James H Rice and Brian J. Rodriguez, September 15, 2020, Journal of Applied Physics.
DOI: 10.1063 / 5.0017899