Small particles feed chemical reactions
A new material made from carbon nanotubes can generate electricity by extracting energy from the environment.
C engineers have discovered a new way to generate electricity using small carbon particles that can only create electricity by interacting with the liquid that surrounds them.
The liquid, an organic solvent, extracts electrons from the particles, generating current that can be used to drive chemical reactions or to power micro- or nanoscale robots, the researchers said.
“This mechanism is new, and this way of generating energy is completely new,” said Michael Strana, a professor of chemical engineering at MIT at Carbon P. Dubbs. “This technology is intriguing because all you have to do is run a solvent through a layer of these particles. This allows you to do electrochemistry, but without wires. “
In a new study describing this phenomenon, researchers have shown that they can use this electric current to trigger a reaction known as alcohol oxidation – an organic chemical reaction that is important in the chemical industry.
Strano is a senior author of the article that appears today (June 7, 2021) in Nature Communications. The study’s lead authors are Albert Tianxiang Liu, a graduate student at the Massachusetts Institute of Technology, and Yuichiro Kunai, a former researcher at the Massachusetts Institute of Technology. Other authors include former student Anton Kotril, postdoctors Amir Kaplan and Hyuna Kim, student Ge Zhang, and recent Massachusetts Institute of Technology alumni Rafid Molah and Yannick Eatmon.
The new discovery is the result of Strano’s research on carbon nanotubes – hollow tubes made of a lattice of carbon atoms that have unique electrical properties. In 2010, Strano demonstrated for the first time that carbon nanotubes can generate “thermoelectric waves”. When the carbon nanotube is coated with a layer of fuel, moving heat pulses or thermoelectric waves travel through the tube, creating an electric current.
This work prompted Strana and his students to discover a related characteristic of carbon nanotubes. They found that when part of the nanotube is coated with a Teflon-like polymer, it creates an asymmetry that allows electrons to flow from the coated to the uncoated part of the tube, generating an electric current. These electrons can be drawn by immersing the particles in an electron-hungry solvent.
To take advantage of this special ability, the researchers created electricity-generating particles by grinding carbon nanotubes and forming them into a sheet of paper. One side of each sheet was coated with a Teflon-like polymer, and the researchers then cut out small particles that could be of any shape or size. For this study, they made particles that are 250 microns by 250 microns.
When these particles are immersed in an organic solvent such as acetonitrile, the solvent adheres to the uncoated surface of the particles and begins to extract electrons from them.
“The solvent takes away the electrons and the system tries to balance it by moving electrons,” says Strana. “There is no complicated battery chemistry inside. It’s just a particle and you put it in a solvent and it starts to generate an electric field. “
“This study skillfully demonstrates how to extract ubiquitous (and often unnoticed) electrical energy stored in on-site electrochemical fusion,” said Jun Yao, an assistant professor of electrical engineering and computer engineering at the University of Massachusetts at Amherst, who is not participated in the study. “The beauty is that it points to a common methodology that can be easily extended to the use of different materials and applications in different synthetic systems.”
The current version of the particles can generate about 0.7 volts of electricity per particle. In this study, the researchers also showed that they could form arrays of hundreds of particles in a small tube. This cramped bed reactor generates enough energy to trigger a chemical reaction called alcohol oxidation, in which the alcohol is converted to an aldehyde or ketone. Usually this reaction is not performed with the help of electrochemistry, as it will require too much external current.
“Because the filled-bed reactor is compact, it has more application flexibility than a large electrochemical reactor,” says Zhang. “Particles can be made very small and do not need external conductors to drive the electrochemical reaction.”
In future work, Strano hopes to use this type of energy production to build polymers using only carbon dioxide as a starting material. In a related project, he has already created polymers that can be regenerated using carbon dioxide as a building material, in a solar-powered process. This work is inspired by the fixation of carbon, a set of chemical reactions that plants use to build sugars from carbon dioxide using energy from the sun.
In the long run, this approach can also be used to power micro- or nanoscale robots. Strano’s lab has already begun building robots on a scale that could one day be used as diagnostic or environmental sensors. The idea of being able to discharge energy from the environment to power these types of robots is appealing, he says.
“That means you don’t have to put the battery in,” he says. “What we like about this mechanism is that you can take energy, at least in part, from the environment.”
Reference: Solvent-Induced Electrochemistry in a Particle with Electrically Asymmetric Carbon Janus by Albert Tiansyan Liu, Yuichiro Kunai, Anton L. Cotril, Amir Kaplan, Ge Zhang, Hyuna Kim, Rafid S. Mola, Yannick L. Eatmon and Michael S Country, June 7, 2021, Nature Communications.
DOI: 10.1038 / s41467-021-23038-7
The study was funded by the US Department of Energy and a grant from the MIT Energy Initiative.