Mesoporous TiO₂ Single-Crystal Polyhedron-Constructed Core–Shell Microspheres: Anisotropic Etching and Photovoltaic Property

A favorable micro-nanostructure is crucial for obtaining superior properties. However, the synthetic techniques for synthesizing the complex morphology still remain a challenge. In this work, we synthesized core–shell-structured submicrometer-sized mesoporous TiO 2 microspheres (MTMs) constructed with mesoporous TiO 2 polyhedrons through a novel anisotropic etching route. The outer shell of the obtained TiO 2 microsphere is constructed by a mesoporous TiO 2 single-crystal nanopolyhedron with exposed (101) facets. Hydrogen peroxide was used as the bubble generator, which simultaneously acted as gas templates for the formation of TiO 2 microspheres. Fluorine ions facilitate the formation of anatase (001) facets at the beginning of the reaction. The anisotropic etching accrued along the [101] direction with an increase in fluorine ions, leaving mesoporous structures and highly exposed (101) facets. Dye-sensitized solar cells (DSSCs), using the as-prepared product as a light-scatting layer, showed a 29.4% increase in conversion efficiency.