A team of engineers combined graphene with titanium dioxide nanoparticles to create a new type of solar catalyst that can absorb pollutants from the air and be much more efficient than other catalysts,media reported. Catalysts can be applied to buildings or street surfaces to improve the city’s air quality.
Although carbon dioxide often makes headlines for air pollution, it is far from the only compound that causes air pollution. Nitrogen oxides and volatile organic compounds emitted through automobile exhaust and industrial processes lead to haze and damage to human health.
Over the past few years, researchers have experimented with titanium dioxide nanoparticles, also known as titanium dioxide, to remove this air pollution. Titanium dioxide acts as a photocatalyst, which means that once activated by light, it breaks down contaminants. This has been used in air-purified concrete and aluminum building panels as well as water filters.
In past work, titanium dioxide surfaces have shown efficiency of up to 45% of the efficiency of converting nitrogen oxides from the atmosphere into harmless nitrates. For the new study, the team managed to increase that to 70 percent. The secret ingredient is graphene.
The researchers used liquid-phase stripping technology to strip the graphene layer off the base material, graphite, but made new adjustments to the routine process – they added titanium dioxide nanoparticles to the mixture. This enabled them to create a new graphene-titanium dioxide nanocomposite.
The material can then be applied to surfaces such as streets, sidewalks or building facades to passively clean the air. It is powered entirely by sunlight, so the nitrates produced are harmless.
“This photocatalytic cement matrix is suitable for buildings and can make surfaces self-cleaning by reducing nitrogen oxides and air pollution – the effect of so-called ‘absorption of haze’,” the researchers said. Graphene can help improve photocatalytic behavior of catalysts such as titanium dioxide and enhance the performance of cement. “
The team tested the mixture by manufacturing photocatalytic plates and exposing them to contaminants. In one test, they used Rodinmin B(which had a molecular structure similar to volatile organic pollutants). After testing in the water and activating it with ultraviolet light, the team found that graphene-titanium dioxide composites degraded 40 percent more than roddamin B, which degraded with a separate titanium dioxide catalyst.
In subsequent tests, the researchers found that graphene, titanium dioxide catalysts degraded nitrogen oxides more than 70 percent more efficiently. “The combination of graphene and titanium dioxide provides excellent results – can be applied to different materials, where concrete is a good example of how we can be widely used to help us achieve a healthier environment,” said Marco Goiss, who was involved in the study. Because it only requires the energy of the sun without additional input. “
While these early results are promising, the team says more needs to be done before the technology can be commercialised. For one thing, graphene is still tricky in mass production, but many scientists are already working on it.
This work was carried out by scientists from Graphene Flagship, the University of Bologna, the Polytechnic University of Milan, CNR, NEST, Italcementi Heidelberg Cement Group, Technion, Eindhoven Polytechnic University and the University of Cambridge.
The study was published in the journal Nanoscale.