Clemson University Scientists Generate Clean Energy with 3D Printed Graphene

You’ve likely heard of some of the most common sources of green energy – solar, wind, etc. Fewer people are familiar, however, with triboelectricity. Triboelectricity is generated when certain materials become electrically charged after coming into contact with other materials, generating friction. In 2017, a group of physicists at Clemson’s Nanomaterials Institute (CNI) invented a simple triboelectric nanogenerator called the U-TENG. It was made only of plastic and tape yet was able to generate electricity from certain motions that brought two materials together, like clapping hands or tapping feet. The energy generated by those motions was detected by a wired external circuit. Electrical energy from the circuit was then stored in a battery or capacitor until needed.

Several months later, the researchers developed a wireless version of the device called the W-TENG. Instead of plastic, 3D printed graphene-PLA nanofiber was used as the bottom electrode, and Teflon was substituted for Kapton tape as the top electrode.

“We use Teflon because it has a lot of fluorine groups that are highly electronegative, whereas the graphene-PLA is highly electropositive. That’s a good way to juxtapose and create high voltages,” said Dr. Ramakrishna Podila, Assistant Professor of Physics at Clemson.

To create the graphene, the researchers exposed graphite to a high frequency sound wave, which sliced it into thin layers of graphene, in a process called sonication. The graphene was then combined with PLA to make a 3D printing filament.

The W-TENG can generate 3,000 volts of electricity, enough to power 25 standard electrical outlets or an LCD monitor. The high voltage generates an electrical field around the W-TENG that can be sensed wirelessly. That electrical energy can also be stored wirelessly in capacitors or batteries.

“It cannot only give you energy, but you can use the electric field also as an actuated remote. For example, you can tap the W-TENG and use its electric field as a ‘button’ to open your garage door, or you could activate a security system — all without a battery, passively and wirelessly,” said Sai Sunil Mallineni, a Ph.D. student in physics and astronomy.

Not only is the W-TENG a potential clean energy source, it’s a possible generator for energy in areas without access to conventional sources of electricity, such as outer space, in the middle of the ocean, or on the battlefield. It could also be used in developing nations with unreliable or no access to electricity.

“Several developing countries require a lot of energy, though we may not have access to batteries or power outlets in such settings,” Podila said. “The W-TENG could be one of the cleaner ways of generating energy in these areas.”

The researchers are in the process of patenting the W-TENG through the Clemson University Research Foundation. CNI Director Dr. Apparao Rao is also talking to national partners about integrating the device into energy applications. Some more work has to be done on the W-TENG first, however. The researchers want to replace the Teflon with a more environmentally friendly electronegative material. One possibility is MXene, a two-dimensional organic compound that has the conductivity of a transition metal and the hydrophilic properties of alcohol.

Rao isn’t making any predictions as to whether the W-TENG will indeed become a competitive renewable energy source. It’s more complicated, unfortunately, than simply making a viable device.

“We can only take it so far as scientists; the economics need to work out in order for the W-TENG to be successful,” he said.

The CNI researchers have certainly made a good start, though. The research was published in a paper entitled “A Wireless Triboelectric Nanogenerator,” which you can access here. Authors of the study include Sai Sunil Kumar Mallineni, Yongchang Dong, Herbert Behlow, Apparao M. Rao, and Ramakrishna Podila.

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[Source: Clemson University]