Cobalt nanorods

Fig. 12 Cobalt nanorods synthesized in the presence of a mixture of oleic acid and a octylamine b dedecylamine c hexadecylamine d octadecylamine...

Fig. 13 Super-lattice of cobalt nanorods a Top view hexagonal b vue de cote c image k haute resolution...

F. Dumestre, B. Chaudret, C. Amiens, M. Fromen, M. Casanove, P. Renaud, and P. Zurcher, Shape control of thermodynamically stable cobalt nanorods through organometalUc chemistry, Angew. Chem. Int. Ed. 41(22), 4286-4289 (2002). 

Figure 20 TEM image of cobalt nanorods. (Reprinted from G. Schmid, D.V. Talapin, E.V. Shevchenko in ed. G. Schmid Nanoparticles. From Theory to Apphcation, Wiley-VCH, Weinheim 2004, with permission from Wiley-VCH)...

Dumestre, F., Chaudret, B.,Amiens, C., Fromen, M.C., Casanove,M.J., Renaud, P.andZurcher, P. (2002) Shape control of thermodynamically stable cobalt nanorods through organometallic chemistry. Angew. Chem., 114, 4462... 

Figure 3.127 TEM (left) and HR-TEM (right) images of cobalt nanorods. Illustration courtesy of Dr. B. Chaudret.

Another exciting example of the effect of particle shape on self-assembly is the formation of the cobalt nanorod superstructures, as observed by Chaudret et al. [52]. 

Figure4.21 Three-dimensional organization of hep cobalt nanorods, (a) Side view (b) Top view. Illustration courtesy of Dr B. Chaudret.

An emerging direction in nanomaterials research concerns the synthesis of multifunctional nanocrystals [62]. Seeded growth [63] of a second material on already preformed nanocrystals has given access to nano-objects associating discrete, nonconcentric, and chemically different domains. Anisotropic nanocrystals due to their distinct reactivity along different facets offer the possibility to position the second domain on a specific facet [64]. Using as seeds cobalt nanorods we have... 

Ligands are also involved in the growth of the NPs, and the choice of acid/amine mixtures allows the dissociation of a nucleation reservoir form a growth reservoir and, therefore, with the help of a dihydrogen atmosphere, the growth of large monodisperse nano-objects, iron nanocubes, and cobalt nanorods, the monodispersity of which results from thermodynamic control [67]. 

This process of crystalHzation using charges was extended to other systems using as an alternative mixtures of amines and long chain carboxylic acids. In this way, super-lattices of nanorods of cobalt and of nanocubes of iron were prepared (vide infra). 

Figure 2 TEM micrographs of (a) hcp-Co self-assembled nanodisks (bar= 100nm) and (b) Fe nanorods respeotively obtained by thermolysis of cobalt and iron oarbonyl oomplexes7 Reproduoed with permission from ACS Publioations.

Figure 7.13 TEM image of self-assembled CoO nanorods, prepared by decomposition of cobalt oleate (size 9 nm x 46 nm) observed after the slow evaporation of a hexane solution of nanorods. (Reprinted with permission from K. An et al. J. Am. Chem. Soc. 2006, 128, 9753. Copyright (2006) American Chemical Society.)...

The synthesis of hcp-Co nanorods and nanowires was also reported [80]. Thermal decomposition of the organometallic cobalt precursor, [Co(T) -CgHi3)(T]" -C8Hi2)], in... 

The PANl/porphyrin nanocomposites have been fabricated using the similar approach [110,111]. To extend the functionalities of the nanocomposites, metalloporphyrin has also been used as template to synthesize CP/ cobalt porphyrin nanocomposites through electrochemical polymerization. Similar to porphyrin, cobalt porphyrin can also form J-aggregates, and many rod-like structures have been observed after dispersing their aqueous solution onto freshly cleaved mica. An electrochemical polymerization forming PPy was templated by J-aggregates of cobalt porphyrin to form PPy/cobalt porphyrin nanocomposites in the presence of cobalt porphyrin in the pyrrole solution [112]. Ihe diameter of the as-synthesized PPy/cobalt porphyrin composite nanorods was aroimd 50 nm when the cobalt porphyrin solution was ultrosonicated for at least three hours before the electropolymerization of pyrrole on the electrode surface. In the presence of cobalt porphyrin, the composite nanorods exhibited excellent elec-trocatalytic activity. 

Different nanocrystals shapes are obtained by variation of the organic stabilizer type and its concentration. For instance, if organometallic compounds such as nickel bis-cyclooctene-l,5-diene(Ni(COD)2) are subjected to the heat treatment and decomposition in the presence of hexadecylamine (GDA) or trioctylphosphenoxide, the nanorods or nanospheres can be obtained [311]. The particles of bracelet shape and 27 nm size have been synthesized in Ref. [312]. The tetrahedral structures [313] have been obtained when the cobalt nanoclusters react with NaAOT/toluene at 130 °C. 

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