CONICET | Buscador de Institutos y Recursos Humanos

The article describes the development of novel nanostructured mesoporous coating systems with improved photocatalytic and antibacterial activity. These systems, consisting on mesoporous or dense TiO2-anatase doped with silver nanoparticles (Ag NPs), were synthesized via a sol-gel technique with hierarchical structures by combining colloidal Ag NPs with TiO2 and SiO2 sols. Photocatalytic and bactericide properties were studied comparing with non-doped TiO2 coatings obtained by similar techniques. Photocatalytic activity was studied through methyl orange decomposition under UV light. Results showed a great increase of photocatalytic activity by Ag doping. The TiO2 coatings doped with Ag NPs showed a potent bactericide activity against the planktonic forms of Gram-negative (enterohemorrhagic Escherichia coli) and Gram-positive (Listeria monocytogenes) pathogens as well as a potent germicide effect against deadly spores of human gas gangrene- and anthrax-producing bacteria (Clostridium perfringens and Bacillus anthracis, respectively). The mechanisms responsible for the increase of photocatalytic and bactericide behaviors related to Ag NPs doping were studied by spectroscopic ellipsometry, UV-Vis spectroscopy, photoluminescence and anodic stripping voltammetry. It was found that the separation of the electron-hole pair contributed to the enhancement of photocatalysis, the presence of local electric field reinforcement being likely present. A possible involvement of decrease 19 of band-gap energy and dispersion by silver nanoparticles are ruled out. Bactericide efficiency was increased by Ag+ ions release.