Nonhydrolytic synthesis of high-quality anisotropically shaped brookite TiO2 nanocrystals.
A surfactant-assisted nonaqueous strategy, relying on high-temperature aminolysis of titanium carboxylate complexes, has been developed to access anisotropically shaped TiO2 nanocrystals selectively trapped in the metastable brookite phase. Judicious temporal manipulation of precursor supply to the reaction mixture enables systematic tuning of the nanostructure geometric features over an exceptionally wide dimensional range (30-200 nm). Such degree of control is rationalized within the frame of a self-regulated phase-changing seed-catalyzed mechanism, in which homogeneous nucleation, on one side, and heterogeneous nucleation/growth processes, on the other side, are properly balanced while switching from the anatase to the brookite structures, respectively, in a continuous unidirectional crystal development regime. The time variation of the chemical potential for the monomer species in the solution, the size dependence of thermodynamic structural stability of the involved titania polymorphs, and the reduced activation barrier for brookite nucleation onto initially formed anatase seeds play decisive roles in the crystal-phase- and shape-tailored growth of titania nanostructures by the present approach.
Buonsanti
Raffaella
R
Scuola Superiore ISUFI, University of Salento, Distretto Tecnologico, via per Arnesano km 5, 73100 Lecce, Italy.
Grillo
Vincenzo
V
Carlino
Elvio
E
Giannini
Cinzia
C
Kipp
Tobias
T
Cingolani
Roberto
R
Cozzoli
Pantaleo Davide
PD
D016880:Anisotropy; D002264:Carboxylic Acids / Q000737:chemistry; D003460:Crystallization; D049329:Nanostructures / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry; D010316:Particle Size; D033362:Powder Diffraction; D013501:Surface-Active Agents / Q000737:chemistry; D013696:Temperature; D013816:Thermodynamics; D014025:Titanium / Q000737:chemistry*
D002264:Carboxylic Acids; D009942:Organometallic Compounds; D013501:Surface-Active Agents; C009495:titanium dioxide; D014025:Titanium