The development of nanocrystalline photocatalytic materials is rapidly a growing field of science and technology. This fact relates to the unique physical and chemical properties of these materials that may be utilised for a wide range of potential applications. Specifically, upon ultraviolet irradiation these materials exhibit photocatalytic activity that enables the oxidative destruction of a wide range of organic compounds and biological species on their surface. Examples of such species include bacteria, viruses, cyanobacteria, algae and fungi and all kinds of proteins or toxic components (self-decontamination effect). In addition, these materials may also exhibit photocatalytically induced superhydrophilicity that converts the hydrophobic character of the surface to hydrophilic when exposed to UV light. This causes the formation of uniform water films on the surface of these materials, which prevents the adhesion of inorganic or organic components and thus retains a clean surface on the photocatalyst. Hence these nanocrystalline photocatalytic materials may be deployed on surfaces of various substrates such as glass, ceramics or metals to provide layers that exhibit self sterilisation and self cleaning properties when they are exposed to the light. The commercial potential for such coatings are massive, including medical applications, architectural (particularly cultural heritage purposes, facade paints, indoor, wall paper, tiles, consumer goods etc.), automotive and food industries (cleaner technologies, non-fogging glass and mirrors, product safety), textile and glass industry, and environmental protection (water and air purification and disinfection).
Among the various nanocrystalline photocatalytic materials that have been studied over the past 30 years research has mainly focussed on titanium dioxide photocatalysis in diverse areas ranging from water and air treatment through to self cleaning glass. Numerous papers have been published on the fundamentals of pure titania systems, and the mechanisms of oxidation and superhydrophilicity have been investigated in detail. Consequently, primarily in Japan, but also in the United States and latterly in China, commercialisation of TiO2 photocatalysis has been initiated in various fields. In Europe, however, although there is extensive academic knowledge in nanostructured materials and photocatalysis with several materials and processes being pioneered, the commercial potential of photocatalytic materials has yet to be realized. Currently the main commercial applications of photocatalysis in Japan are architectural tensile structures with over 50% of industrial turnover, followed by ceramics and glass. In China, wall paints already have been used, with TiO2 dispersed in silicone-type paints. More than 3,000 patents have been issued, mainly on anatase-based photoactive form of TiO2. The total turnover of the sale of anatase has been booming in the last years and it is expected to reach one billion Euros in 2006.
Among the various nanocrystalline photocatalytic materials that have been studied over the past 30 years research has mainly focussed on titanium dioxide photocatalysis in diverse areas ranging from water and air treatment through to self cleaning glass. Numerous papers have been published on the fundamentals of pure titania systems, and the mechanisms of oxidation and superhydrophilicity have been investigated in detail. Consequently, primarily in Japan, but also in the United States and latterly in China, commercialisation of TiO2 photocatalysis has been initiated in various fields. In Europe, however, although there is extensive academic knowledge in nanostructured materials and photocatalysis with several materials and processes being pioneered, the commercial potential of photocatalytic materials has yet to be realized. Currently the main commercial applications of photocatalysis in Japan are architectural tensile structures with over 50% of industrial turnover, followed by ceramics and glass. In China, wall paints already have been used, with TiO2 dispersed in silicone-type paints. More than 3,000 patents have been issued, mainly on anatase-based photoactive form of TiO2. The total turnover of the sale of anatase has been booming in the last years and it is expected to reach one billion Euros in 2006.
Therefore, development of new and optimisation of existing photocatalytically active materials exhibiting activity upon visible light with surface characteristics of improved performance and of the high chemical and physical stability are crucial for broader scale utilization of photocatalytic systems in commercial application. Such materials together with the development of technically applicable self aligning photocatalytic coating systems adaptable to the major substrates (polymers, glass, ceramics or metals) will represent a ground breaking step change in this field particularly in the economic viability of a range of potential processes. The first visible light systems via doping of titanium oxide with N, S and C have been already prepared recently, but no systematic investigations have been carried out to date. It is, however, expected that the soft chemical approach employing multiply doped mixed oxide heterostructures for tailored micro- and mesoporous architectures can provide a significant breakthrough in the development of visible light photoactive systems. The supra-molecular engineering can additionally allow tuning of the hydrophilicity and hydrophobicity of photocatalysts. The environmental stability of nanoparticles can be also improved through hydrothermal or lyothermal processes.
In addition to the development of highly active photocatalytic materials and coating systems, there is also great need to develop suitable standards for the characterization of photocatalytic and hydrophilic properties of these materials. Standardization protocols are essential for integration of the research effort in different laboratories and to compare the performance of commercial products. Even though extensive research activities in photocatalysis have been carried out on a worldwide basis for the last twenty years, it was not until 2003 that the Japanese Standard organisation JIS has started an initiative to develop standards in photocatalysis. Based upon this JIS initiative an ISO committee has commenced with the development of respective standards for photocatalysis at the end of 2003. There are European companies active in the field of photocatalytical applications, e.g. Czech RAKO and German DSCB producing photocatalytical tile or English Pilkington and French Saint Gobain producing photocatalytically active glass, however, all of them have problems how to present their products to the customers and to prove them the function of their products by accepted testing methods. Therefore, any successful industrial production and commercialisation of photo-catalytic systems within Europe will strongly depend also on the development of the EU standards with the further effort of their approval as ISO standards to ensure their worldwide acceptance.
It is obvious that the approach to undertake these tasks in fundamental knowledge acquisition, as well as products and processes is clearly multidisciplinary. The topics require expertise in material science, various fields of chemistry, physics, molecular/micro biology and medicine. There is also need of closer cooperation between academia and industry in order to transfer technological know-how of photocatalysis into the commercial products. Feedback and crossover between these activities are critical to maximize delivery on breakthroughs to the application processes, for which standardization is also required. This prompts a concerted integration of the European photocatalytic community in order to achieve these goals.
The specific aim of this Action is to bring together European scientists and engineers from various fields and research groups in order to combine their particular knowledge, state of art equipment, experience and technical know-how in an effective way towards the design, synthesis and testing of the new photocatalytical nanomaterials and their utilization in the specific industrially relevant application fields such as self-cleaning and anti-microbial surfaces, water treatment, air purification and general hygienic applications. The joint effort is needed to a) gather the necessary manpower and scientific expertise to carry out the first class research needed and b) to compete with Japan and USA in the development of new products with potential large scale applications.
The scientific and technological objectives of this Action are in line with the European policy of exploring the nanosciences, nanotechnologies, materials, new production and integration of new knowledge and technologies on nanomaterials for industrial applications. This Action will pull together European groups with leading expertise in different nanoscale basic aspects of photocatalysis, molecular and microbiology and materials science and will combine their particular knowledge, experience and skills in an effective way towards scientific knowledge breakthroughs. The Action also aims to broaden the training and education of young European scientists to improve and develop of new skills and expertise. With co-operation of European industrial partners catalyst and materials manufacturers will closely work together with coating specialists to exploit the knowledge developed by researchers looking into the basics.
Regarding the standardization aspects this Action is seen as being complementary to CEN WG 166, which is looking on standardization of nanotechnologies. It is intended to establish close links with the European Committee for Standardization to coordinate the standardization procedures and to ensure the dissemination of the know-how coming from this Action to the whole European standardisation community. The Action will also benefit from synergies and contacts developed by the 6th Framework Programme Integrated Projects CONCORDE devoted to studies on oxide nanostructured catalysts and FULLSPECTRUM aiming better exploitation of the solar spectrum in the photovoltaic conversion of the solar energy; COST Action 529 dealing with development of novel light sources; and by European-Japanese Initiative on Photocatalytic Applications and Commercialisation (EJIPAC). There are also national programs, e.g. Finnish National Technology Programme on Surface Sciences PINTA, Czech Research Centre for Nanotechnology NANOPIN, with which this Action will cooperate. As such, this COST Action offers an ideal platform to group the existing collaborations and to allow for a large exchange between the different European groups focussing on the development of photocatalytical nanomaterials and nanotechnologies and their integration for industrial applications.