Executive Summary : | Photocatalytic performance of nanomaterials is influenced by shape, size, and composition, leading to facet-controlled synthesis of metal oxide nanostructures. Faceted materials are divided into low-index and high-index-facet materials, with low-index facets having 0 and 1 Miller indices, and high-index facets having at least one index greater than 1. The performance of facet-dependent nanostructures can be evaluated more explicitly if only one set of surface facets is present. The final product of exposed faceted materials is restricted to low-index facets under thermodynamic control, which lack high reactive sites for chemical reactions. High-index facet structures have more catalytic active sites but are difficult to produce concave structures due to their higher surface energy and faster growth rate. The Gibbs-Wulff theorem approximates the equilibrium shape of the crystal, with high-energy surface facets growing quickly and occupying a small portion of the surface. Designing high-index-faceted metal oxide nanostructures with improved catalytic activity remains a challenging task. |