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Topologically controlled growth of colloidal semiconductor/magnetic nanocrystal heterostructures: site-selective functionalization of TiO2 nanorods with either γ-Fe2O3 or ε-Co spherical domains
|Marianna Casavola 1, Raffaella Buonsanti 1, Vincenzo Grillo 2, Elvio Carlino 2, Cinzia Giannini 3, Miguel Angel Garcia 4, Fabia Gozzo 5, Liberato Manna 1, Roberto Cingolani 1, Pantaleo Davide Cozzoli 1|
1. National Nanotechnology Laboratory of CNR-INFM (NNL), via per Arnesano Km 5, Lecce 73100, Italy
The recognition of the dimensionality-dependent physical-chemical properties of nanoscale inorganic matter has stimulated efforts toward the fabrication of nanostructured materials in a systematic and controlled manner. Colloidal routes have now advanced to the point of allowing facile access to a variety of finely size- and shape-tailored nanocrystals (NCs) by adjusting thermodynamically and kinetically-limited growth processes in liquid media. While refinement of this synthetic ability is far from being exhausted, the increasing demand for multi-purpose nano-objects has recently oriented efforts of nanochemistry research to envision first prototypes of multimaterial hybrid nanocrystals (HNCs) with a topologically controlled composition.1 Here, we describe surfactant-assisted seeded-growth approaches to fabricate elaborate noncentrosymmetric HNCs, which comprise semiconductor/magnetic sections fused together through small inorganic interfaces. The nanocrystal heterostructures are fabricated by heterogeneous nucleation of either γ-Fe2O3 or ε-Co domains onto anatase TiO2 nanorod seeds.2-3 The latter can be decorated at either their tips or longitudinal sidewalls, attaining epitaxial heterointerfaces even in the presence of a large lattice mismatch between the connected crystal structures. Our results illustrate how the surfactant-modulated reactivity of the exposed TiO2 seed facets, the interfacial strain induced at the relevant junction regions, and the occurrence of local lattice distortion fields interplay with each other at the nanoscale, ultimately dictating the final HNC topology. These studies suggest useful criteria for the rational design of novel generations of nanocrystal heterostructures with high structural complexity and increased functionality.
 P. D. Cozzoli, et al Chem. Soc. Rev. 2006, 35, 1195.
 R. Buonsanti et al. J. Am. Chem. Soc. 2006, 128, 16953.
 M. Casavola et al. Nano Letters 2007, 7, 1386.
Presentation: Oral at E-MRS Fall Meeting 2007, Symposium A, by Pantaleo Davide Cozzoli
See On-line Journal of E-MRS Fall Meeting 2007
Submitted: 2007-05-12 19:21 Revised: 2009-06-07 00:44