The influence of substrate defects on the growth rate of palladium nanoparticles on a TiO2(110) surface

We investigated the growth rate of small palladium particles on TiO2(1 1 0) substrates with high and modest defect concentrations, using scanning tunn elling microscopy, The defects on the substrate surface are created as a co nsequence of reduction of the oxide crystal in ultra-high vacuum. The level of oxygen depletion depends on the preparation conditions, resulting in ei ther a strongly reduced surface with a high level of oxygen depletion, or a mildly reduced surface with a modest level of oxygen depletion. After depo sition of palladium at room temperature on a mildly reduced titania surface , palladium clusters predominantly cover steps. On a strongly reduced sampl e, clusters are smaller and distributed over the terraces. At elevated temp eratures the particles grow in both cases, but the growth rate on the mildl y reduced surface is higher than on the strongly reduced surface. Finally, on a mildly reduced substrate the particles are flatter than on a strongly reduced substrate. (C) 2001 Elsevier Science B.V. All rights reserved.