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Yusuf Hamied Department of Chemistry

Three men in lab coats in a laboratory

(Left to right) Erwin Reisner, Subhajit Bhattacharjee, Motiar Rahaman. Taken by Carolina Pulignani.

The Reisner group has developed a solar-powered reactor that converts two distinct waste products; greenhouse gases and plastics, into useful products at the same time.

This is a first for solar-powered reactors and an important step in shifting to a more sustainable and circular economy. This research is critical since plastic waste and greenhouse gas emissions are two problems that require urgent attention.

“Converting waste into something useful using solar energy is a major goal of our research,” said Professor Erwin Reisner from the Yusuf Hamied Department of Chemistry, who led this research. “Plastic pollution is a huge problem worldwide, and often, many of the plastics we throw into recycling bins are incinerated or end up in landfill.”

Converting waste to useful products

The system converted carbon dioxide into syngas, a component used to make sustainable liquid fuels, and plastic bottles into glycolic acid which is widely used in the cosmetics industry. These results are reported in the journal Nature Synthesis. This is just one example of how the reactor can be used as there are many different options to change which products are created by changing the catalyst in the reactor.

“A solar-driven technology that could help to address plastic pollution and greenhouse gases at the same time could be a game-changer in the development of a circular economy,” said Subhajit Bhattacharjee, who is in the Reisner group and the paper’s co-first author.

“We also need something that’s tuneable, so that you can easily make changes depending on the final product you want,” said co-first author Dr Motiar Rahaman who is also in the Reisner group.

A versatile system

One key benefit of the reactor is that the researchers designed different catalysts that could create different end products. Different catalysts were tested to produce carbon monoxide and formate in addition to syngas, along with glycolic acid.

“Generally, CO2 conversion requires a lot of energy, but with our system, basically you just shine a light at it, and it starts converting harmful products into something useful and sustainable,” said Rahaman. “Prior to this system, we didn’t have anything that could make high-value products selectively and efficiently.”

“What’s so special about this system is the versatility and tuneability – we’re making fairly simple carbon-based molecules right now, but in future, we could be able to tune the system to make far more complex products, just by changing the catalyst,” said Bhattacharjee.

A sustainable future

This work will continue thanks to new funding from the European Research Council. The researchers hope to tune the reactor so that it can produce more complex molecules. This research is critical since plastic waste and greenhouse gas emissions are two problems that require urgent attention.

“Developing a circular economy, where we make useful things from waste instead of throwing it into landfill, is vital if we’re going to meaningfully address the climate crisis and protect the natural world,” said Reisner. “And powering these solutions using the Sun means that we’re doing it cleanly and sustainably.”

Reisner also leads the Cambridge Circular Plastics Centre (CirPlas), which aims to eliminate plastic waste by combining blue-sky thinking with practical measures.


S. Bhattacharjee, M. Rahaman, V. Andrei, M. Miller, S Rodríguez-Jiménez, E. Lam, C. Pornrungroj and E. Reisner, Photoelectrochemical CO2 -to-fuel conversion with simultaneous plastic reforming, Nature Synthesis (2023).