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Design of iso-material heterostructures of TiO2via seed mediated growth and arrested phase transitions
- Source :
- Physical Chemistry Chemical Physics. 22:25366-25379
- Publication Year :
- 2020
- Publisher :
- Royal Society of Chemistry (RSC), 2020.
-
Abstract
- Stabilization of different morphologies of iso-material native/non-native heterostructures is important for electron-hole separation in the context of photo-electrochemical and opto-electronic devices. In this regard, we explore the stabilities of different morphologies of rutile ("native", ground state phase) and anatase ("non-native" phase) TiO2 heterostructures through (1) seed-mediated growth and (2) a thermally induced arrested phase transition synthesis protocol. Furthermore, the experimental results are analyzed through a combination of Density Functional Tight Binding (DFTB) and Finite Element Model (FEM) methods. During the seed-mediated growth, anatase is grown over a polydispersed and polycrystalline rutile core through thermal treatment yielding core-shell, Janus and yolk-shell iso-material heterostructures as observed from HRTEM. The arrested phase transition of anatase to rutile at different annealing temperatures yields rutile crystals in the subsurface region of the anatase and rutile/core-thin anatase/shell heterostructures but does not yield a Janus structure. Small particles that can be modeled via DFTB computations suggest that: (1) a heterostructure of the rutile/core-anatase/shell is energetically more stable than the anatase/core-rutile/shell or any other Janus configuration, (2) the off-centered rutile/core-anatase shell is more favorable to the mid-centered rutile/core-anatase shell and (3) Janus heterostructures can be stabilized when the mass ratio of the rutile seed to anatase overgrowth is high. FEM simulations, performed to evaluate the importance of stress relaxation in bicrystalline materials without defects, suggest that Janus structures can be stabilized in larger particles. The present studies add to the heuristics available for synthesizing iso-material heterostructures.
- Subjects :
- Phase transition
Anatase
Materials science
General Physics and Astronomy
02 engineering and technology
Thermal treatment
010402 general chemistry
021001 nanoscience & nanotechnology
01 natural sciences
0104 chemical sciences
Rutile
Chemical physics
Stress relaxation
Crystallite
Janus
Physical and Theoretical Chemistry
0210 nano-technology
High-resolution transmission electron microscopy
Subjects
Details
- ISSN :
- 14639084 and 14639076
- Volume :
- 22
- Database :
- OpenAIRE
- Journal :
- Physical Chemistry Chemical Physics
- Accession number :
- edsair.doi...........dc7f87ce46c85c6cb4bf66e58325ba51