Deposition of Nonstoichiometric Tritungsten Oxides on the TiO2(110) Surface: A Possible Way to Stabilize the Unstable Clusters in the Gas Phase

A series of nonstoichiometric tritungsten oxide clusters W3On (n = 7, 8, 10) deposited on the TiO2(110) surface have been investigated by using first-principles DFT calculations. Various possible configurations have been considered for each W3On/TiO2(110) system, based upon ab initio molecular dynamics simulations and thermodynamical analyses. After deposition of the W3On cluster, the position of the Fermi level is sensitive to the stoichiometry of the cluster. This is due to the obvious charge transfer occurring from the oxygen-deficient W3On cluster (n < 9) to the TiO2(110) surface, whereas the direction of charge transfer is reversed for the deposition of the oxygen-enriched W3On cluster (n > 9). Our results clearly indicate that the deposition of clusters with different stoichiometric compositions offers an opportunity to control the properties of the support, including the conductivity, the surface work function, and the catalytic performance over a sufficient range. In addition, our results show that the relative stability of nonstoichiometric tritungsten oxide clusters in the gas phase is not preserved after landing on the TiO2(110) surface. Therefore, from a thermodynamical point of view, it may provide a possible way to stabilize the unstable clusters in the gas phase by choosing a suitable support.