Titania surface structures for directed growth of metal nanoparticles via metal vapour deposition and metal organic chemical vapour deposition

Abstract

In this paper metal vapour deposition and metal organic chemical vapour deposition have been used to produce nanoscale metal particles on various TiO₂(110) surfaces. The nanoparticles (Pd and Rh) are imaged directly by scanning tunnelling microscopy at ambient and elevated temperature in ultra high vacuum. The surface reconstruction of the TiO₂ to a cross-linked (1 × 2) is used to form highly corrugated rectangular arrays that direct the growth of the Pd clusters. Thermal annealing at first induces a flattening and then a sintering of the nanoparticles. Ultimately the particles form a wide distribution of shapes and sizes. A crystal displaying crystallographic shear planes, composed of a self assembled array of alternating up -down step edges on the terrace, is used to direct the growth of Rh nanoparticles from [Rh(CO)₂Cl]₂. The particles are shown to grow mainly at the top edge of each step that runs at an angle to the principal directions of the surface.