The amount of plastic waste produced globally has doubled over the past two decades—and plastic production is expected to triple by 2050—with most of it ending up in landfills, incinerated or otherwise mismanaged, according to the Organization for Economic Cooperation and Development. Some estimates suggest only 5% is actually being recycled.

"Waste plastic is rarely recycled because it costs a lot of money to do all the washing, sorting and melting down of the plastics to turn it into a material that can be used by a factory," said Kevin Wyss, a Rice graduate student and lead author on a study published in Advanced Materials that describes how he and colleagues in the lab of chemist James Tour used their flash Joule heating technique to turn plastic into valuable carbon nanotubes and hybrid nanomaterials.

"We were able to make a hybrid carbon nanomaterial that outperformed both graphene and commercially available carbon nanotubes," Wyss said.

Graphene, carbon nanotubes and other carbon-based nanomaterials are generally strong and chemically robust, have low density and lots of surface area, and possess conductivity and broadband electromagnetic absorption abilities. This makes them useful in a variety of industrial, medical and electronics applications such as composites, coatings, sensors, electrochemical energy storage and more.

"What was really interesting about our results this time is that we were able to make these carbon nanotubes with bits of graphene attached on the ends," Wyss said. "You can think of the structure of this new hybrid nanomaterial as similar to bean sprouts or lollipops. These are normally really hard to make, and the fact that we were able to make them out of waste plastic is really special."