Enhancement of nano titanium dioxide photocatalysis in transparent coatings by polyhydroxy fullerene

Microbe transmission via surfaces is a common mode for the spreading of infectious diseases. A simple way to combat disease transmission via surfaces is to apply antimicrobial coatings. We have developed a thin, transparent, photocatalytic coating for rapid destruction of microbes. The coating uses polyhydroxy fullerene (PHF) as an enhancer for nano TiO2 photocatalysis. A nanocomposite of PHF and TiO2 was synthesized through physical mixing of the two components in aqueous suspension. The nanocomposite was characterized by dynamic light scattering, zeta potential and Langmuir adsorption isotherm. A coating of the PHF/TiO2 nanocomposite was characterized by scanning electron microscopy. Photocatalytic activity of the nanocomposite coating, as indicated by degradation of organic dye (Procion red MX-5B) under UVA illumination, was optimal at a PHF/TiO2 ratio of 0.01. The nanocomposite coating degraded the organic dye twice as fast as a coating of TiO2 that contained no PHF. The nanocomposite coating was then applied to photocatalytically inactivate spores of Aspergillus niger, a household fungus commonly implicated in asthma. The nanocomposite inactivated spores three times as fast as a coating of TiO2 containing no PHF. Changes to the morphology of A. niger spores due to photocatalysis were investigated using scanning electron microscopy. (C) 2012 Elsevier B.V. All rights reserved.