A new solar-powered catalyst that can extract pollutants from the air has been developed by a group of engineers from various European institutes within the Graphene Flagship initiative created by the European Union in 2013. The new catalyst could, in particular, make it possible to create surfaces of buildings, roads or other public facilities capable of absorbing some of the pollutants usually found in the air of cities.
The new catalyst is made of various materials, including graphene nanoparticles and titanium dioxide. Titanium dioxide nanoparticles (also known as titania) have already received considerable attention in the past in the world of research for their ability to clean the air of air pollution. Titania, in fact, once exposed to sunlight, begins to degrade nitrogen oxides and volatile organic compounds oxidizing them and making them inert or harmless products.
The new photocatalytic coating then shows even more powerful photodegrading properties compared to naked titania. As Marco Goisis, research coordinator of Italcementi, one of the companies involved in this research, explains, photocatalysis remains one of the most effective ways known to limit environmental pollution because it is based on a reaction activated simply by sunlight.
The new graphene-titania surface that researchers have created can be applied, for example, to concrete used to build buildings and roads. Once the photodegradation products have become harmless, they could then be washed away by rain or wind or simply cleaned manually.
The researchers have already experimented with the new surface and obtained excellent results. “The coupling of graphene with titania has given us very good results in the form of powder, and could be applied to different materials, of which concrete is a good example for widespread use, helping us to get a healthier environment. It is low-maintenance and environmentally friendly, as it requires only the energy of the sun and no other input,” explains Goisis himself.
Currently the only obstacles to overcome are the usual cost of graphene, a material that is unfortunately still not cheap and not easily mass-produced, and the interactions between the catalyst and the host material, interactions that are not yet well developed. Moreover, there is still some doubt about the long-term stability of such a coating in an outdoor environment that can be “battered” for long periods by highly stressful weather conditions.