Tuning the shape and crystal phase of TiO2 nanoparticles for catalysis.

Synthesis of TiO2 nanoparticles with tunable shape and crystal phase has attracted considerable attention for the design of highly efficient heterogeneous catalysts. Tailoring the shape of TiO2, in the crystal phases of anatase, rutile, brookite and TiO2(B), allows tuning of the atomic configurations on the dominantly exposed facets for maximizing the active sites and regulating the reaction route towards a specific channel for achieving high selectivity. Moreover, the shape and crystal phase of TiO2 nanoparticles alter their interactions with metal species, which are commonly termed as strong metal-support interactions involving interfacial strain and charge transfer. On the other hand, metal particles, clusters and single atoms interact differently with TiO2, because of the variation of the electronic structure, while the surface of TiO2 determines the interfacial bonding via a geometric effect. The dynamic behavior of the metal-titania interfaces, driven by the chemisorption of the reactive molecules at elevated temperatures, also plays a decisive role in elaborating the structure-reactivity relationship.