Ab initio calculations on the early growth state of Pt on TiO2(1 1 0) rutile and the role of CO molecule

The growth of Pt on rutile TiO2(1 1 0) and its interaction with CO were investigated by means of ab initio calculations. The hydrogen-saturated cluster approach was employed to model the neutral TiO2 surface. The interaction of Pt atoms was evaluated at three possible adsorption sites on the rutile surface. The most stable adsorption site of Pt atoms was at the O hollow site where calculations were performed with the B3LYP and HF methods; the MP2 method resulted in Pt atoms being most stable at Ti hollow sites. The interactions of square planar and square pyramidal Pt clusters with TiO2 explain the tendency of Pt to grow in islands. The tendency towards monolayer formation found under CO exposure at low growth temperature originated from the higher mobility of Pt atoms and lower strain within the cluster in the presence of CO. The adsorption of CO on Pt was weakened by the presence of an interaction between Pt and TiO2.