The nanoparticle coatings are the outcome of the Ecofotomat project, which involved the university and the L’Urederra R+D Centre, plus construction company Obras y Servicios TEX.
Researcher Javier Goicoechea said the coatings have special nanoparticles with a photocatalytic effect.
‘The nanoparticles interact with the light, thus triggering a series of chemical reactions that clean the air and break down the dirt,’ he said.
According to a statement, concrete was used as the basic construction material. L’Urederra manufactured the nanoparticles and adapted them so that they could be incorporated into the coatings, while TEX provided the concrete and the technical specifications on the building material.
‘There are ceramics that have these types of coatings, but here we are working with concrete and with liquid solutions, because we want the final coating to resemble a paint as much as possible: one that can be applied on site, has a cost that is not too high, and is sufficiently tough to withstand the elements,’ said Goicoechea.
‘The good thing is that we are talking about very thin coatings of less than a micron and that adapt very well to the profile of the material. For example, concrete is always very porous and this coating will cause the whole porous surface to become active when the sunlight hits it,’ he added.
The coating is also claimed to be capable of degrading certain chemical compounds that become attached to the surface, and that way the spread of bacteria or fungi, for example, is hampered.
‘This is not like when one speaks about coatings with an anti-bacterial agent that is gradually released, and the moment comes when it runs out, and consequently stops working,’ said Goicoechea. ‘What we are talking about here is a material that has a built-in property: when the sunlight hits it, it produces free radicals on its surface that attack the air pollutants, specifically the monoxides and the nitrogen oxides.
‘What we need to come up with is a matrix that is tough and permanent enough to immobilise those nanoparticles on the surface and that ensures that the coating remains in place; and all that at an affordable cost.’
Ecofotomat has been partly funded by the Spanish Ministry for the Economy and Competitiveness and by the European Regional Development Fund. The project is expected to end in June 2013.