A New Indicator for Single Metal Dispersion on a TiO2(110) Surface Premodified with a Mercapto Compound

Ni and Pt structures evaporated onto a TiO2(110) surface premodified with ortho-mercaptobenzoic acid (o-MBA) were studied using polarization-dependent total reflection fluorescence X-ray absorption fine structure analysis to determine the effects of the premodification on the dispersion of the metal atoms over the TiO2(110) surface. Ni was found to be atomically dispersed with the formation of S-Ni-O bonds (where the S is provided by the o-MBA and the 0 is present in the TiO2 lattice) on the surface. In contrast, Pt underwent aggregation to form small clusters. The varying behavior of these metals on the o-MBA-modified TiO2(110) surface is discussed based on the energy difference between sulfur-metal-oxygen and metal-metal bond formations, and we propose a new indicator for single metal dispersion on the TiO2(110) surface.