Core-shell nanorods

Fig. 7.6 Schematic diagram of core-shell nanorods of (a) InP-CdS (b) InP-ZnTe and use of nanorods in water photodecomposition. In (a), electrons are holes are localized in the shell and the core, respectively whereas, in (b), holes and electrons are localized in the shell and the core, respectively.

Yu ZG, Piyor CE, Lau WH, Berding MA, MacQueen DB (2005) Core-shell nanorods for efficient photoelectrochemical hydrogen production. J Phys Chem B 109 22913-22919... 

Figure 18 Absorption (solid line) and PL (dashed line) spectra for medium-length (3.3 x 21 nm) CdSe nanorods, (a) Core nanorods without ZnS shell, (b) (Core)shell nanorods with thin CdS-ZnS shells ( 2 monolayers of shell material, where the CdS buffer shell comprises 35% of the total shell), (c) (Core)shell nanorods with medium CdS-ZnS shells ( 4.5 monolayers of shell material, where the CdS buffer shell comprises 22% of the total shell). PL spectra were recorded following photoannealing of the samples ...

CdSe/ZnS core-shell nanorods ca. d t) 4x25 and 5 20 nm were synthesized according to the published procedures [6]. The polymeric polymethylmetacrylate... 

CdSe/ZnS core-shell nanorods with size ca. 4x25 nm were synthesized according to published procedures [6]. The polymeric polymethylmetacrylate (PMMA) film with CdSe nanorods was placed between two transparent indium-tin oxide (ITO) electrodes sealed with epoxy glue. The electric field influence on the nanorods PL was studied by applying a constant dc voltage between transparent ITO electrodes. The PL was excited by 488 nm Ar-ion laser. The PL spectra at different voltages were measured by a combination of inverted microscope and liquid nitrogen (LN)-cooled CCD camera based spectrometer. 

Chemical bath deposition can also be used to produce core-shell nanorod film electrodes, for example, Ti02 CdS (69). It is possible to couple chemical bath deposition and the microwave radiation procedure. The advantage of this process is that there is no need for the heat treatment of the samples after the synthesis, since the microwave does the job. ZnO nanorods with an orientation perpendicular to the substrate can be synthesized in 12 min by this method, starting from zinc nitrate (or zinc acetate) and urea (or hexamethylene tetramine Reference 70). 

Core-shell nanorods represent composite nanorods in which the core and shell dimensions can be independently varied. The physicochemical properties (e.g. band gap, near-infrared absorption) can be tuned by varying the dimension of the core and the shell. The major synthetic routes for the preparation of the core-shell nanorods are ... 

The core-shell nanorods that have been prepared using these methods are summarized in Table 7.4. A few specific cases are discussed below. 

For the preparation of CdSe/ZnS core-shell nanorods (86), first CdSe nanorods are prepared by decomposing a cadmium precursor, Cd(CHs)2, and selenium metal in the... 

TABLE 7.4 Examples of Core-Shell Nanorods Prepared by Different Methods... 

Figure 7.15 TEM images of Au-Ag core-shell nanorods prepared by the reduction of AgCl on the surface of An nanorods, (a) AucoreAgsheii(thin) nanorods, (b) AucoieAgsheii(thick) nanorods. (Reprinted with permission from C. S. Ah et al. J. Phys. Chem. B 2001, 105, 7871. Copyright (2001) American Chemical Society.)...

Nanocomposites are materials in which nanoparticles (in this case, nanorods) are dispersed in a continuous matrix. The matrix may be a polymer, nanorods, or other nanoparticles. Nanorod composites find applications in diverse areas such as efficient charge storage, removal of contaminants (e.g. surfactant) from water, emissivity control devices, and metallodielectrics, and so on. A number of methods such as electroless deposition, the sol-gel method, the hydrothermal method, solution casting, carbother-mal reduction, the template-based method, the sonochemical method, and electrospinning can be used to prepare composite nanorods. Nanorod composites are different from core-shell nanorods. In core-shell nanorods, the coating is uniform, whereas in the nanorod composite (consisting of a nanorod and a nanoparticle on a surface), fine nanoparticles are dispersed on the surface of the nanorods. Some specific examples of the preparation of nanocomposites consisting of nanorods are described below. 

Cai, G., Tu, J., Zhou, D., Zhang, J., Xiong, Q., Zhao, X., Wang, X., Gu, C., 2013. Multicolor electrochromic film based on ri02 polyaniline core/shell nanorod array. J. Phys. Chem. C 117,15967-15975. 

Wang, Z. L., Z. L. Zhu, J. H. Qiu, and S. H. Yang. 2014. High performance flexible solid-state asymmetric supercapacitors from MnOfZnO core-shell nanorods// specially reduced graphene oxide. Journal of Materials Chemistry C 2 1331-1336. 

Y. Hao, et al.. Efficient semiconductor-sensitized solar cells based on poly(3-hexylthiophene) CdSe ZnO core-shell nanorod arrays. The Journal of Physical Chemistry C, 2010. 114(18) p. 8622-8625. 

Jazirehpour, M. and Alizadeh, A. Synthesis of boron carbide core-shell nanorods and a qualitative model to explain formation of rough shell nanorods. J. Phys. Chem. C, 2009,113,1657-1661. 

Some work has also been recently carried out on the solution synthesis of bimetallic nanorods, employing gold nanorods as preformed cores. Jang and co-workers synthesized Au Ag core-shell nanorods using the electrochemical method to obtain the gold nanorods and the seed-mediated mechanism to get the desired core-shell structure. The combination of the different optical resonances from the core and the shell metals leads to a quite spectacular optical spectrum from these composite, anisotropic nanoparticles. 

Liu, M., and Guyot-Sionnest, P. [2004] Synthesis and optical characterization of Au/Ag core/shell nanorods,/ Phys. Chem. B, 108,5882-5888. Kreibig, U. [1974] Electronic properties of small silver particles the optical constants and their temperature dependence, J. Phys. F Met Phys., 4, 999-1014. 

X. Xu, A.K.K. Kyaw, B. Peng, D. Zhao, T.K. S. Wong, Q. Xiong, X.W. Sun, A.J. Heeger, A plasmonically enhanced polymer solar cell with gold-silica core-shell nanorods, Org. Electron. 14 (2013)2360-2368. ... 

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