In order to study the photodegradation of molecules located at the vicinity of a titanium dioxide photocatalyst, a well-defined structure comprised of alternating micro-stripes of TiO2 and silicon was prepared on silicon wafers. Onto this structure, a cross-linked self-assembled monolayer (SAM) of Octadecyltrichlorosilane (OTS) was chemisorbed. The kinetics of the photodegradation of the anchored SAM on the hybrid structure was then measured in-situ by FTIR under controlled humidity (8% RH). It was found that the photogenerated oxidizing species, formed on the titanium dioxide well-defined micro-domains, are capable of inducing, within minutes, the mineralization of the aliphatic chains anchored to the inert silicon domains, even when these chains were located as far as 20 microns away from the titanium dioxide micro-zones. Based on complementary experiments with alkanethiols on gold in a Au/TiO2 hybrid system, it was shown that the observed remote mineralization was not based on a diffusion – through – air mechanism. The observation that the oxidizing species can induce mineralization far from the locus of their formation may have large effect on the design and modeling of porous photocatalysts having “dark” pores.
Photocatalytic Degradation of Self-Assembled Monolayers Anchored at the Vicinity of Titanium Dioxide
Published: January 2002
Authors: Zemel, E.; Haick, H.; Paz, Y.
Published in: J. Adv. Oxid. Technol., 5 (1), 27-32