Bactericide & photocatalytic behaviour of TiO2-anatase mesoporous coatings doped with Ag nanoparticles: characterization of the antimicrobial and sporocide effects.

ROLDÁN V.; DE OÑA P.; GRAU R.; PELLEGRI N.

Material Science and Engineering C

Elsevier

Lugar: Washington; Año: 2014 vol. 43 p. 630 - 640

0928-4931

Here we describe the development of novel nanocompounds with improved photocatalytic and antibacterial activity. These composites, made of mesoporous and dense TiO2-anatase and silver nanoparticles, were synthesized via a sol-gel technique with hierarchical structures by combining colloidal Ag nanoparticles with TiO2 sols. Photocatalytic and bactericide properties were studied comparing with no-doped TiO2 coatings obtained by similar techniques. Photocatalytic activity was studied through the methyl orange decomposition under UV light incidence. Results showed a great increase of photocatalytic activity by Ag doping. The TiO2 coatings doped with Ag nanoparticles showed a potent bactericide activity against the planktonic forms of Gram-negative (enterohemorrhagic Escherichia coli) and Gram-positive (Staphylococcus aureus and 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 of the increase of photocatalytic and bactericide properties by Ag nanoparticles doping were studied by spectroscopic ellipsometry, UV-Vis spectroscopy, atomic force microscopy, photoluminescence and anodic stripping voltammetry. It was found that the separation of the electron-hole pair contributed to the enhancement of photocatalysis, while the presence of local electric field reinforcement is probably present. A possible involvement of decrease of band-gap energy and dispersion by silver nanoparticles are ruled out. On the other hand, bactericide properties were increased by Ag+ ions release.