A DFT study of metastable \textit{h}-WO$_{3}$ surfaces

Polycrystalline WO$_{3}$ has gained considerable interest as an efficient oxide material for photoreactions [1], and its surface-dependent catalytic properties have been exploited by shape-control crystal engineering of this oxide for photochemistry reactions e.g. water-splitting. Recently, hexagonal single crystal WO$_{3}$ nanorods with dominant (0001) and (11$\bar{2}$0) facets were synthesized and these nanorods are found to be highly effective photoanode [2] However, the precise local atomic structures and surface orientations of this metastable \textit{h}-WO$_{3}$, which are important for understanding surface-dependent photoreactions, are not well studied. In this work, using first-principles density-functional theory (DFT), we consider the various orientations and terminations of \textit{h}-WO$_{3}$ surfaces and address the predicted nanomorphologies under corresponding experimental conditions based on the DFT-derived Gibbs-Wulff polyhedrons. We provide a microscopic perspective for its potential applications in photoreactions by studying the surface energetics and electronic structure. [1] Y. Ping and G. Galli, \textit{J. Phys. Chem. C} \textbf{118}, 6019 (2014); [2] P. M. Rao \textit{et al.}, \textit{Nano Lett.} \textbf{14}, 1099 (2014)