Lasers and 2D materials adapted to fight global plastic threat

11 Jul 2024

Texas Engineers use transition metal dichalcogenide and laser process to tackle problem polymers.

A global research team led by engineers at the University of Texas (UT), Austin, TX, has developed a way to laser-treat the molecules in plastics and other materials to break them down into their smallest parts for future reuse.

The discovery, which involves laying these materials on top of two-dimensional materials called transition metal dichalcogenides and then lighting them up, has the potential to improve the disposal of plastics that are nearly impossible to break down with current technologies.

“By harnessing these reactions, we can explore new pathways for transforming environmental pollutants into valuable, reusable chemicals, contributing to the development of a more sustainable and circular economy,” said Yuebing Zheng, professor in the Cockrell School of Engineering’s Walker Department of Mechanical Engineering and one of the project leaders. “This discovery has significant implications for addressing environmental challenges and advancing green chemistry.”

The research is described in Nature Communications. The team includes researchers from the University of California, Berkeley; Tohoku University in Japan; Lawrence Berkeley National Laboratory; Baylor University; and Pennsylvania State University.

How it works

The researchers used a low-power laser to break the chemical bonding of the plastics and create new chemical bonds that convert the materials into luminescent carbon dots. Experimental work has been undertaken with a 532 nm laser delivering up to 2.5 mW. Other experiments have used a laser transmitting at 660 nm.

Carbon-based nanomaterials are in high demand because of their many capabilities, and these dots could potentially be used as memory storage devices in next-generation computer devices, says the Texas team.

“It’s exciting to potentially take plastic that on its own may never break down and turn it into something useful for many different industries,” said Jingang Li, a postdoctoral student at University of California, Berkeley who started the research at UT.

The specific reaction is called C-H activation, in which carbon-hydrogen bonds in an organic molecule are selectively broken and transformed into a new bond. In this research, the 2D materials catalyze this reaction that leads to hydrogen molecules morphing into gas. That clears the way for carbon molecules to bond with each other to form the information-storing dots.

Further research and development are needed to optimize the light-driven C-H activation process and scale it up for industrial applications. However, the team says that this study represents “a significant step forward in the quest for sustainable solutions to plastic waste management.”

The light-driven C-H activation process demonstrated in this study can be applied to many long-chain organic compounds, including polyethylene and surfactants commonly used in nanomaterials systems.

The research was funded by various institutions, including the U.S. National Institutes of Health, National Science Foundation, Japan Society for the Promotion of Science, the Hirose Foundation and the National Natural Science Foundation of China.