Photocatalytic materials for environmental cleaning and health protection

Heterogeneous photocatalytic processes and related applications, involving functional innovative photonic materials in the nanometer scale are investigated. The scientific effort aims at improving the efficiency of photocatalytic processes via: a) increase of the photocatalyst effective surface area; b) efficient separation of the photogenerated charge carriers (e- and h+); c) photocatalytic sensitization into the Vis light region-shift of the absorption onset; d) judicious balance of photocatalytic and superhydrophylic properties on multi-dynamic surfaces able to photochemically decompose harmful organics, kill bacteria and viruses and being easily self-cleaned; e) increased anticancer and anticoagulant action of titanium dioxide on neoplasm and inflammatory cells.

The research activities concern the development and evaluation of performance of novel and innovative nanostructured semiconductor based photocatalysts including dispersions, powders and their derivatives, films, foams, composites and modified matrixes. The work comprises: (a) control and optimization of size, roughness, surface complexity, morphology, self-cleaning, anti-fogging and antibacterial properties of nanocrystalline titania; (b) use of inorganic-organic templates (i.e. cellulose compounds and derivatives, PEO, PEG, related polymers, surfactants) combined with hydrothermal treatment under mild temperature (autoclaved) to avoid unwanted structural modifications (keep the anatase phase that promotes the photocatalytic effect better than the rutile phase); (c) production of mesoporous titanium oxide materials with three-dimensional networks of spheroidal or cubic voids; (d) surface modification of nanostructured titanium dioxide thin films by monodispersed noble metal nanomarticles (i.e. Ag, Au) with fractal characteristics; (e) tuning of the electronic properties via doping of the titania material with nitrogen, phosphorus and sulfur components and simultaneous determination of optimum dopant concentration to avoid antagonistic charge recombination effects; (f) development of composite materials including mixed nanostructured oxides (i.e. FexOy/TiO2 SiO2/TiO2) and photocatalytic light cement (based on nanostructured titania, perlite and Portland cement) with controlled physical (hydration kinetics), mechanical (compressive strength), chemical (aging, carbonation) properties; (g) design, fabrication, modeling, evaluation, and optimisation of photocatalytic reactors, both liquid and gas phase; (h) optimization of interaction between titania nanoparticles/nanoparticle dispersions and cancer cells in the presence of photosensitization factors.

Important impact is expected on environmental photocatalytic applications such us removal of pollutants from air and water, deodorization, prevention of stains, sterilization. Various applications in the every day life as well as in building constructions (the photocatalytic cementeous materials can serve simultaneously as structural and photochemically active component) are also considered.

Speaker: Dr. Polycarpos Falaras, Research Director, Institute of Physical Chemistry, NCSR Demokritos, 153 10 Aghia Paraskevi Attikis
E-mail: papi@chem.demokritos.gr
Time: Monday, 27 June 2005, 13:00