Mesoporous TiO_2 core-shell spheres composed of nanocrystals with exposed high-energy facets: Facile synthesis and formation mechanism

摘要

A facile new method that combines electrospray and hydrothermal treatment is used to prepare mesoporous core-shell TiO_2 spheres with high specific surface areas and high pore volumes. Interestingly, the resulting TiO_2 spheres are composed of anatase TiO_2 nanocrystals with exposed step-like {001} and smooth {010} facets. The percentage of exposed {001} facets can be adjusted by changing the experimental parameters used in the electrospray and hydrothermal treatment processes, such as the contents of poly(N-vinyl-2-pyrrolidone) and acetic acid. The combination of high specific surface area (>100 m~2 g~(-1)), high pore volume (>0.30 cm~3 g~(-1)), useful pore size (10-15 nm), spherical core-shell structure, and exposed high energy facets makes these TiO_2 spheres an important candidate for use in many photoelectrochemical applications. The formation mechanism of the mesoporous TiO_2 spheres is also studied. The great advantage of this method is that interesting and complicated mesoporous superstructures can be prepared using electrospray technology.