Role of point defects on the reactivity of reconstructed anatase titanium dioxide (001) surface

The chemical reactivity of different surfaces of titanium dioxide (TiO(2)) has been the subject of extensive studies in recent decades. The anatase TiO(2)(001) and its (1 × 4) reconstructed surfaces were theoretically considered to be the most reactive and have been heavily pursued by synthetic chemists. However, the lack of direct experimental verification or determination of the active sites on these surfaces has caused controversy and debate. Here we report a systematic study on an anatase TiO(2)(001)-(1 × 4) surface by means of microscopic and spectroscopic techniques in combination with first-principles calculations. Two types of intrinsic point defects are identified, among which only the Ti(3+) defect site on the reduced surface demonstrates considerable chemical activity. The perfect surface itself can be fully oxidized, but shows no obvious activity. Our findings suggest that the reactivity of the anatase TiO(2)(001) surface should depend on its reduction status, similar to that of rutile TiO(2) surfaces

Growth of Metal Clusters at Surfaces

In the present chapter we will discuss the creation of surface supported metal clusters through nucleation and growth in Molecular Beam Epitaxy (MBE). MBE is commonly used to grow thin epitaxial films from the vapor phase onto single crystal substrates under ultra-high vacuum (UHV) conditions [1]