Smog-eating graphene composite reduces atmospheric pollution


06-12-2019
Left: Photocatalytic panel exposed outdoor. The purple section is treated with a pollutant. Right: Three weeks later, pollutant has been degraded by the photcatalyst  Credit: Italcementi

An international group of scientists, including from the University of Cambridge, have developed a graphene composite that can ‘eat’ common atmospheric pollutants, and could be used as a coating on pavements or buildings.

Working in collaboration with the Italcementi HeidelbergCement Group and other partners, the Cambridge scientists developed a photocatalyst that degrades up to 70% more atmospheric nitrogen oxides (NOx) than standard titania nanoparticles in tests on real pollutants.

Atmospheric pollution is a growing problem, particularly in urban areas and in developing countries. According to the World Health Organization, one out of every nine deaths worldwide can be attributed to diseases caused by air pollution. Organic pollutants, such as nitrogen oxides and volatile compounds, are the main cause of this, and they are mostly emitted by vehicle exhausts and industry.

While researchers are developing new technologies and energy sources that will drastically reduce the volume of pollutants emitted into the atmosphere in the first place, they are also on the hunt for new ways to remove more pollutants from the atmosphere. Photocatalysts such as titania are one way to do this. When titania is exposed to sunlight, it degrades harmful nitrogen oxides and volatile organic compounds present at the surface, oxidising them into inert or harmless products.

Now, in a study published in the journal Nanoscale, the researchers demonstrated that a composite of titania and graphene – a two-dimensional form of carbon - has significantly more powerful photodegradation properties than bare titania.

Researchers from the Cambridge Graphene Centre prepared and tested the composite, confirming its ability to photocatalytically degrade pollutant molecules, then researchers at Italcementi applied the coating to concrete to investigate its potential for environmental remediation.

“We decided to couple graphene to the most-used photocatalyst, titania, to boost the photocatalytic action,” said co-author Marco Goisis from Italcementi. “Photocatalysis is one of the most powerful ways we have to depollute the environment because the process does not consume the photocatalysts. It is a reaction activated by solar light.”

By performing liquid-phase exfoliation of graphite – a process that creates graphene – in the presence of titania nanoparticles, using only water and atmospheric pressure, the scientists created the new graphene-titania nanocomposite.

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Image: Left: Photocatalytic panel exposed outdoor. The purple section is treated with a pollutant. Right: Three weeks later, pollutant has been degraded by the photcatalyst

Credit: Italcementi

Reproduced courtesy of the University of Cambridge

 

The University of Cambridge is acknowledged as one of the world's leading higher education and research institutions. The University was instrumental in the formation of the Cambridge Network and its Vice- Chancellor, Professor Stephen Toope, is also the President of the Cambridge Network.

University of Cambridge (cam.ac.uk)