Remote photocatalytic activity as probed by measuring the degradation of self-assembled monolayers anchored near microdomains of titanium dioxide

A cross-linked self-assembled monolayer (SAM) of octadecyltrichlorosilane (OTS) was chemisorbed on well-defined structures, comprised of alternating microstripes of TiO2 and silicon. The kinetics of the photodegradation of the anchored SAM on the hybrid structure was then measured in situ by FTIR under controlled humidity and surface temperature. It was found that mineralization of the aliphatic chains anchored to the inert silicon domains can occur, even when these chains are located as far as 20 mum away from the photocatalytic titanium dioxide microdomains. An apparent first-order kinetics was found for each of the two domain types. Apparent activation energies were calculated on the basis of the temperature-dependent measurements. 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 and on the developing of hybrid photocatalysts.