An economical and low-emissions route to the conversion of waste plastics into high-yield hydrogen gas and high-value graphene has been demonstrated by Rice University researchers.

The catalyst-free process exposes plastic waste samples to rapid flash Joule heating for about four seconds, bringing their temperature up to 3,100 Kelvin (2,827˚ C). The hydrogen present in the material vaporizes, leaving behind graphene.

Unlike fossil fuel-based and green hydrogen production schemes, this technology described in Advanced Materials yields virtually no carbon dioxide emissions — a 39% to 84% reduction in emissions compared to other production methods is indicated by life cycle assessments. Superior economics are an added benefit of the flash Joule heating approach as the value of the graphene by-product could offset the costs of producing hydrogen.

Transmission electron microscope image of layered stacks of nano-scale flash graphene sheets formed from waste plastic. Source Kevin Wyss/Tour Lab, Rice University

“In this work, we converted waste plastics — including mixed waste plastics that don’t have to be sorted by type or washed — into high-yield hydrogen gas and high-value graphene,” said lead author Kevin Wyss. “If the produced graphene is sold at only 5% of current market value — a 95% off sale — clean hydrogen could be produced for free.”