Investigating surface properties and lithium diffusion in brookite-TiO₂

Surfaces properties of TiO₂ in the brookite phase and the lithium diffusion are studied using density functional theory (DFT) and interatomic potential simulations. Simulations predict that the brookite surfaces have a higher intrinsic Lewis acidity compared to the other polymorphs due to the presence of four coordinated Ti atoms on the surface in contrast to the most stable surfaces of anatase and rutile which have five coordinated Ti surface atoms. The surface reactivity of the brookite is then expected to be higher for catalysis. The (210) surface is the most stable calculated surface and some experimental morphologies have been revisited. Regarding Li intercalation, the migration occurs along the c-direction and open channel surfaces are desired, therefore particles exposing the (001) surface. Those differences on chemical/physical properties highlight the importance to control the nanoparticle shapes for a given application.