The reactor, developed by researchers at the University of Cambridge, is powered by solar energy and could be a more economical and sustainable alternative to current recycling methods based on chemical processes. The team claims that their method could create a circular system in which one waste stream helps to resolve another. Their results have been published in the journal Joule.

Global plastic production exceeds 400 million tons annually, but only 18% is recycled. The rest is burned, dumped in landfills, or ends up polluting ecosystems. Researchers say their method, known as solar-powered acid photoforming, could help address the growing accumulation of plastic waste globally.
The scientists designed a photocatalyst tough enough to withstand the highly corrosive effects of acid, while utilizing the acid present in used car batteries, which is typically neutralized and discarded.

“The discovery was almost accidental,” said Professor Erwin Reisner of Cambridge’s Yusuf Hamied Department of Chemistry, who led the research. “We used to think that acid was completely out of the question in these solar systems because it would simply dissolve everything. But our catalyst didn’t, and suddenly a whole new world of reactions opened up.”

“Acids have long been used to break down plastics, but we’ve never had a cheap, scalable photocatalyst that could withstand them,” explained lead author Kay Kwarteng, a doctoral student in Reisner’s research group. “Once we solved that problem, the advantages of this system became clear.”

The method developed by Kwarteng, Reisner, and their colleagues begins by treating plastic waste with battery acid, breaking down the long polymer chains into chemical components such as ethylene glycol. A photocatalyst then converts these compounds into hydrogen and acetic acid (the main component of vinegar) when exposed to sunlight.
In laboratory tests, the reactor generated high levels of hydrogen and produced acetic acid with high selectivity. Furthermore, it operated for over 260 hours without any loss of performance.
This approach works with multiple types of plastic waste, including those currently difficult to recycle, such as nylon and polyurethane. This represents a significant advance over current recycling technologies, which are primarily limited to PET.

The system works not only with new laboratory-grade acid but also with acid recovered from car batteries, which contain between 20% and 40% acid. These batteries are replaced in large quantities every year worldwide. Although the lead is usually recovered for reuse, the acid generates additional waste after neutralization.

“It’s an untapped resource,” Kwarteng said. “If we can recover the acid before neutralizing it, we can reuse it again and again to break down plastics—it’s a win-win situation, since we avoid the environmental impact of neutralizing the acid and use it to generate clean hydrogen.”
The researchers emphasize that their method could reduce costs by an order of magnitude compared to other photoforming approaches, primarily because the acid allows for increased hydrogen production and can be reused instead of being consumed.

Although challenges remain—such as designing reactors capable of withstanding corrosive conditions—Kwarteng asserts that the chemical basis is sound. “These acids are already handled safely in industry. The question now is one of engineering: how to build reactors that operate continuously and process real waste.”
The researchers emphasize that this method will not replace conventional recycling, but it can complement it by treating contaminated or mixed plastics that currently lack a viable reuse pathway.

“We’re not promising to solve the global plastic problem,” Reisner said. “But this demonstrates how waste can be turned into resources. The fact that we can generate value from plastic waste using sunlight and acid from discarded batteries makes this process a very promising option.”
The team plans to commercialize this technology with support from Cambridge Enterprise, the university’s innovation arm, and funding from UKRI. The research has also been supported by several academic and scientific institutions in the UK.

Reference:
Papa K. Kwarteng et al. 'Solar Reforming of Plastics using Acid-catalyzed Depolymerization.' Joule (2026). DOI: 10.1016/j.joule.2026.102347