Research Agenda - Academic Research Projects

Healthcare Associated Infections (HAI) are most common in hospital intensive care units, nursing homes, and operating theatres. MRSA (methicillin-resistant Staphylococcus aureus), is an example of a deadly bacteria which has the ability to resist the most powerful antibiotics. it is not possible to control an outbreak of MRSA exclusively by personal hygiene. Therefore the development of a self-sterilizing hospital atmosphere is an important step in achieving a better hygiene environment.

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More than 90% of Ireland’s energy requirements are met by fossil fuels. Under the present situation the nation can no longer depend on oil for the production of electricity. There is a need to find a reliable energy source and photovoltaic energy has been identified as one of the potential technologies to over come the energy crisis. The maximum stable efficiency reported to date is 9.4%. Any improvement in the efficiency of current solar cells will be beneficial to the scientific development of non-conventional energy sources. Nano layered ZnO has been found to be superior to the conventional transparent conducting oxide materials in Si based solar cells due to the better electro-optical properties. Low temperature crystallization with a textured surface is essential to integrate these ZnO based materials in Si solar cells. Sol gel processing has the potential to make textured thin films with low temperature crystallization. The aim of the project is to improve the efficiency of Si based solar cells using ZnO based sol gel transparent conducting oxides

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The objective of this project is to develop novel synthetic methods to fabricate mesoporosity in titanium dioxide and to reduce production costs of of NTERA’s current NanoChromics TM display technology. The outcome of Strand 1 project will also improve the reliability, expand the application and reduce the manufacturing cost of NTERA’s current NanoChromics TM display technology. The success of the recently commenced Nanofoam project (in collaboration with NTERA Ltd.) is aided by the recruitment of a new postgraduate student, Mr Pradeepan Periyat. The student working on the project will obtain training in various disciplines of engineering and science, as well as gain experience in an emerging field of nanotechnology.

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This report presents a systematic study of metal doped semiconductor system such as TiO 2 and ZnO. In the case of TiO 2, two different preparation methods were attempted for effective silver doping. The silver can be incorporated by irradiating the reaction mixture during preparation to reduce silver ion to silver metal or by direct calcination of the sol–gel material to decompose silver nitrate to silver. Of the two methods, we found the latter produces a more effective photocatalytic material (6–50 % improvement in catalytic efficiency), which is attributed to the fact that the silver is homogeneously dispersed throughout the material. The efficiency of the materials were examined using a Q-Sun solar simulator (visible light) and in Dublin summer sunlight (latitude 54 ◦N). In both cases, the addition of increasing amounts of silver, for both batches of samples, significantly increases the rate of degradation of a model dye, rhodamine 6G (R6G), increasing the rate of degradation from 0.06 min−1 for TiO 2 to 0.34 min−1 for 5 mol% Ag–TiO 2. This is attributed to the increasing visible absorption capacity due to the presence of silver nanoparticles. The thin films of the corresponding samples were also prepared and characterised. The transmission spectroscopy shows the presence of silver Plasmon resonance band at 400nm which is attributed to the red shift in wavelength and increased photocatalytic activity. This work ‘Silver doped titanium dioxide nanomaterial for enhanced visible lightphotocatalysis’ was accepted in the journal, J. Photochem. Photobio. A. (2007), in press. A detailed investigation of effect of silver in retaining the anatase phase stability and role of acetic acid (as a chelating agent) in silver doping is under consideration.

Silver doping was carried out with another important wide band gap semiconductor ZnO with different mol% silver calcined at different temperatures. The reaction conditions were optimised and photocatalytic activity has been compared with a standard material. According to the Preliminary studies, 3mol% silver doped ZnO at 600 oC was found to be highly photoactive than the other samples. More characterisation and investigations on the mechanistic part is underway. The effect of N-doping in TiO 2 has also been attempted in collaboration with another post graduate student Pradeepan Periyat (J. Phys. Chem. C 111, (2007), 1605).

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This project aims to utilise visible light absorbing materials to degrade pollutants from vehicle exhausts in urban areas. These materials will be incorporated into transparent surfaces for application onto sunlight exposed building surfaces and they will photochemical degrade pollutants such as nitrogen monoxide. This has a consequent effect in reducing the amount of tropospheric ozone in urban areas. The project will synthesise materials and examine their catalytic activity on nitrogen monoxide, nitrogen monoxide – ozone mix and exhaust pollutants.

5 mol % silver doped titanium dioxide sol-gel was prepared using titanium isopropoxide as a precursor. The TiO 2 sol-gel was then used to coat glass slides. Dip coating procedure was used and several sol-gel coatings were applied to a number of slides. Nitrogen monoxide (NO) and sulfur dioxide (SO 2) were initially chosen as analyte gases. NO proved to be difficult to work with because of the ease at which it undergoes oxidation in air to form nitrogen dioxide (NO 2). SO 2 showed high levels of degradation in air when irradiated with light, indicating unwanted excitation reactions.

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The project deals with designing coatings for surfaces that can be easily cleaned, smooth, and inhibit the growth of fungi and bacteria, specifically Staphylococcus Aureus. The coating is a polymer which is doped with an active agent, in this case a biocidal metal. When harmful bacteria come in contact with the coating, the metal leaches ions to the surface that kill the microbes. The project has many healthcare applications

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