Monomeric, Two-Dimensionally Ordered WO${}_3$ Clusters on Anatase TiO${}_2$(101)

Abstract

We combined scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) experiments with density functional theory (DFT) calculations to study dispersed tungsta clusters on anatase TiO${}_2$(101). Following two different preparation methods, we found that monomeric WO${}_3$ species are the most stable configuration rather than WO${}_3$ trimers, (WO${}_3$)${}_3$. The WO${}_3$ monomers form tetrahedral WO${}_4$ structures on anatase TiO${}_2$(101), with one W$-$O bond and two W$-$O$-$Ti linkages per WO${}_3$ monomer. Locally, the WO${}_3$ monomers form well-ordered (2$\times$1) structures. The discovered geometric structure of WO${}_3$ on anatase TiO${}_2$(101) opens up numerous opportunities for fundamental studies addressing tungsta and accurate structure activity studies of WO${}_3$/TiO${}_2$ model catalysts.