Carbon dioxide (CO₂) emissions and plastic waste are two of the most pressing environmental problems facing the world today, but a device designed by Cambridge scientists may help tackle both at once. The team has demonstrated a new version of their solar reactor, which uses sunlight to convert CO₂ and plastic bottles into useful chemicals.

The Cambridge team unveiled a version of their solar reactor just six months ago. It was made up of two chambers, one that processed CO₂ and the other plastic waste, with the whole thing powered by a perovskite solar cell. That version, however, only worked with concentrated CO₂ from a cylinder, which is useful as a proof of concept but doesn’t necessarily apply to real-world settings.

So for the new version, the team tweaked it to work with CO₂ from flue gas or even just ambient air. First the air is pumped through an alkaline solution, which traps only the CO₂ while allowing the other gases, such as oxygen and nitrogen, to escape as bubbles. This concentrated CO₂ can then be processed, with the help of the other chamber.

“The plastic component is an important trick to this system,” said Dr Motiar Rahaman, co-first author of the study. “Capturing and using CO₂ from the air makes the chemistry more difficult. But, if we add plastic waste to the system, the plastic donates electrons to the CO₂. The plastic breaks down to glycolic acid, which is widely used in the cosmetics industry, and the CO₂ is converted into syngas, which is a simple fuel.”

The team says this technology could go a long way towards tackling both of these major environmental hazards, and eventually could help pave the way towards a fossil-fuel-free future.

“We’re not just interested in decarbonization, but de-fossilization – we need to completely eliminate fossil fuels in order to create a truly circular economy,” said Professor Erwin Reisner, lead author of the study. “In the medium term, this technology could help reduce carbon emissions by capturing them from industry and turning them into something useful, but ultimately, we need to cut fossil fuels out of the equation entirely and capture CO2 from the air.”

The research was published in the journal Joule.

Source: Cambridge University