COMPNANOALD – Self-cleaning walls... a graffiti artist's nightmare!
Sun-fired pollution-eating nano-fibres, novel night-vision devices, super waterproofing materials... these are just some of the applications that award-winning Hungarian scientist Dr Imre Miklós Szilágyi came up with in his EU-supported nano-science project exploring new materials and techniques at the molecular level.
© Dr Imre Miklós Szilágyi
European researchers are leading the quest to master the nano-sciences – the world of the infinitesimally small, where 1 nanometre is one-billionth of a metre or where tiny molecules are some 50 000 times smaller than human hair. The hunt is on to find novel composite materials which can be combined and manipulated to form complex but extremely useful properties applicable to a range of industries, technologies and other scientific endeavours.
Imagine, for example, walls that clean themselves simply by spraying on a special nano-fibre which reacts to sunlight and literally eats away at organic pollution, dirt and even some types of graffiti. The savings on cleaning for municipalities worldwide could be huge.
"With the visible light-active photo-catalysts I've been working on, you could have clean walls without having to scrub them manually," says Dr Szilágyi of the Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics. "What's more, the nano-fibres are prepared in an environmentally friendly way using green chemistry!"
Dr Szilágyi's CompNanoALD project was able to delve deeper than ever before into these complex nano-structures using a technique called Atomic Layer Deposition (ALD). ALD is a unique tool, he says, because it can "deposit one atomic layer of a material at a time in a step-wise manner".
The trick is to control the way chemicals deposit on a surface, which is harder when the object is not flat or consistent in texture, notes Dr Szilágyi. He applied ALD to create incredibly precise and flexible thin films (layers of material) with uniform surfaces even on three-dimensional objects, such as inorganic nano-fibres, carbon nano-tubes, or indeed naturally occurring objects like leaves.
Detecting hazardous gases, harvesting energy... and more
Today, better thin-film deposition is critical to developments in the semiconductor industry – which makes microchips for electronic devices – and, increasingly, green technologies such as solar cells for energy storage.
By combining different properties, or adding brand new functionality, Dr Szilágyi has found innovative ways of creating and using nano-patterns to develop consistent, controllable structures. These include materials with fine-tuned properties to detect hazardous gases, harvest solar energy and copy surfaces found in biology or nature (i.e. lotus leaves).
"The copied 'nano-leaf' could be programmed to react differently to sunlight or water, leading to new super waterproof materials for buildings, clothing, and so on," explains the researcher. Readjusting the surface of the lotus leaf, he adds, meant the surface properties of various biological tissues or bacteria could be programmed, opening up new horizons in biology.
Other promising avenues for the Hungarian scientist's work include the ability to grow functional coatings on cellulose fibres to help incorporate them in biodegradable plastic materials, which can be used in car body parts, for instance. Dr Szilágyi tuned the surface of flexible plastic membranes as well, which can now detect light or electrons. The resulting so-called 'flexible multi-channel plates', he reveals, are very promising for novel night-vision devices, among other applications.
"We've already seen outstanding results using these new atomic deposition techniques, yet the potential of ALD in nanotechnology has not yet been exploited to its full extent," predicts Dr Szilágyi. "But the Marie Curie fellowship I completed this year has definitely helped me push the frontiers of ALD significantly further."
A chemist and engineer, Imre Miklós Szilágyi has received several awards including the Hungarian Academy of Science's Young Scientist Award (2010) János Bolyai fellowship (2011-14), and a Marie Curie Fellowship for career development. The latter allowed him to study and work at Helsinki University, Finland, where he was hosted by the ALD expert, Prof. Markku Leskelä. Dr Szilágyi has contributed to books, conferences and numerous scientific journals and is in the process of creating a dedicated ALD research group after the fellowship.