In situ atomic-scale HRSTEM study of the solid state transformation of anatase nanoparticles into rutile
EMSL Project ID
48133
Abstract
Titanium dioxide (TiO2) has been used in various applications such as photocatalysts1, solar generation of hydrogen2, methanol fuel cells3, anodes for lithium rechargeable batteries4, and photovoltaic cells5. It has been reported that rutile exhibits high rates of recombination in comparison to anatase6. Some mixed phases, such as Degussa P-25, have high photoactivity due to the transferring of electrons from rutile to anatase trapping sites, which hinders the charge recombination7,8. Moreover, while anatase is the stable phase at small (nm) particle size, rutile is the stable phase of bulk TiO29 . In addition, the formation of branched TiO2 appears to involve a process of anatase attachment to rutile nanowires10. Thus, controlling the phase of TiO2 is critical for uncovering phase-function relationships and producing functional materials. The goal of this work is to investigate the mechanism of the transformation from anatase to rutile in the solid state by in situ HRTEM/HRSTEM and to reconstruct the transformation in 3-D at the atomic level. The transformation from anatase into rutile is well known, however, the mechanism by which it occurs, its dependence on particle size, shape and proximity to other particles of anatase or rutile, and the factors that trigger its occurrence are not understood. Here we propose to use EMSL instrumentation to perform high-resolution TEM/STEM imaging experiments of anatase particles in order to observe their transformation into the rutile phase in solid state and establish an understanding of this important nanomaterial phase transformation and the atomic-scale processes that lead to particle-wire integration when the precursor particles and growing wire have distinctive structures.
Project Details
Start Date
2013-11-13
End Date
2014-09-30
Status
Closed
Released Data Link
Team
Principal Investigator