Chapter - 9

CORE-SHELL NANOPARTICLES

Fig. 9.1: Transmission electron micrographs of silica coated gold nanoparticles. The shell

thicknesses are (a) 10 nm, (b) 23 nm, (c) 58 nm, and (d) 83 nm. Reprinted with permission from

Liz-Marzan, et al. (L. M. Liz-Marzan, M. Giersig, P. Mulvaney, Langmuir, 1996, 12, 4329.).

Copyright (1996) American Chemical Society.

Fig. 9.2: TEM image of ZrO2 coated Ag nanoparticles. Reprinted with permission from Tom, et

al. (R. T. Tom, A. S. Nair, N. Singh, M. Aslam, C. L. Nagendra, R. Philip, K. Vijayamohanan, T.

Pradeep, Langmuir, 2003, 19, 3439). Copyright (2003) American Chemical Society.

Fig. 9.3: TEM image of Pt-maghemite core-shell nanoparticles having different shell thickness

made with different shell-forming precursors. The shell thicknesses are 3.5 nm and 5.4 nm,

respectively (left to right). Reprinted with permission from Teng, et al. ( X. Teng, D. Black, N. J.

Watkins, Y. Gao, H. Yang, Nano Lett., 2003, 3, 261). Copyright (2003) American Chemical

Society.

Fig. 9.4: HRTEM images of Ag@ZrO2 core-shell nanoparticles functionalized with a stearate

monolayer. From Nair et. al.( A. S. Nair, T. Pradeep, I. MacLaren, J. Mater. Chem., 2004, 14,

857.). Reproduced with permission from the Royal Society of Chemistry.

Fig. 9.5: TEM images of Gold-silica inverse opals. The core dimension is ~15 nm and the silica

shells are around 8, 18 and 28 nm, respectively. Scale bars are 50 nm in all cases. Reprinted from

( D. Wang, V. Salgueirino-Maceira, L. M. Liz-Marzan and F. Caruso, Adv. Mater., 2002, 14,

908.). Copyright (2002) Wiley-VCH.

Fig. 9.6: TEM images of Au nanoparticles (left) coated with Pt (right) in the ratio 1:2. Reprinted

with permission from Henglein. ( A. Henglein, J. Phys. Chem. B, 2000, 104, 2201.). Copyright

(2000) American Chemical Society.

Fig. 9.7: TEM of polypyrrole coated SiO2 core-shell nanoparticles. Reproduced from ( C. L.

Huang, E. Matijevic, J. Mater. Res., 1995, 10, 1327.). Copyright 1995 Materials Research

Society, also published in F. Caruso, Adv. Mater., 2001, 13, 11. Copyright (2001) Wiley-VCH.

Fig. 9.8: TEM of polypyrrole-capped Au nanoparticles (left) and with further increase in shell

thickness by polymerization with poly (N-methylpyrrole). Reprinted with permission from

Marinakos, et al. ( S. M. Marinakos, J. P. Novak, L. C. Brousseau, A. B. House, E. M. Edeki, J.

C. Feldhaus, D. L. Feldheim, J. Am. Chem. Soc., 1999, 121, 8518.). Copyright (1999) American

Chemical Society.

Fig. 9.9: TEM of LbL assembled polystyrene-capped Au nanoparticles. Reproduced from

F. Caruso, Adv. Mater., 2001, 13, 11. Copyright (2001) Wiley-VCH.

Fig. 9.10: Powder XRD pattern of Pt@Fe2O3 core-shell nanoparticles. Reprinted with permission

from Teng, et al. ( X. Teng, D. Black, N. J. Watkins, Y. Gao, H. Yang, Nano Lett., 2003, 3, 261.).

Copyright (2003) American Chemical Society.

Fig. 9.11: Cyclic voltammetry responses of core-shell nanosystems. Reprinted from ( D. S.

Koktysh, X. Liang, B.-G. Yun, I. Pastoriza-Santos, R. L. Matts, M. Giersig, C. Serra-Rodriguez,

L. M. Liz-Marzan, N. A. Kotov, Adv. Funct. Mater., 2002, 12, 255.) and ( R. T. Tom, A. S. Nair,

N. Singh, M. Aslam, C. L. Nagendra, R. Philip, K. Vijayamohanan, T. Pradeep, Langmuir, 2003,

19, 3439.), respectively. Copyrights (2002) Wiley-VCH and (2003) American Chemical Society,

respectively.

Fig. 9.12: Surface plasmon resonance in metal nanoparticles in an electromagnetic field. The

displacement of the conduction band electrons relative to the nuclei can be seen. Reprinted with

permission from Kelly, et al. ( K. L. Kelly, E. Coronado, L. L. Zhao, G. C. Schatz, J. Phys.

Chem. B, 2003, 107, 668.). Copyright (2003) American Chemical Society.

Fig. 9.13: Dispersion diagram showing the conditions of surface plasmon resonance absorption

as a function of the wavelength of the incident light. Reproduced from ( P. Mulvaney, L. M. Liz-

Marzan, M. Giersig, T. Ung, J. Mater. Chem., 2000, 10, 1259 ). Reproduced with permission

from the Royal Society of Chemistry.

Fig. 9.14: The absorption spectra of Au@SiO2 colloids as a function of solvent refractive index

(top figures) and Ag@TiO2 (bottom A) and Ag@ZrO2 (bottom B) as a function of core

dimension (A) and shell thickness (B). Reprinted with permission from Liz-Marzan, et al. ( L. M.

Liz-Marzan, M.Giersig, P. Mulvaney, Langmuir, 1996, 12, 4329.). (top) and Tom, et al.6

(bottom). Copyright (1996 and 2003, respectively) American Chemical Society.

Fig. 9.15: Transmitted and reflected colors from Au@SiO2 multilayer thin films with varying

silica shell thickness. Reprinted with permission from ( T. Ung, L. M. Liz-Marzan, P. Mulvaney,

J. Phys. Chem. B, 2001, 105, 3441). Copyright (2001) American Chemical Society.

Fig. 9.17: TEM images of Ag@TiO2 core-shell nanoparticles (a) and the TiO2 nanoshells formed

from the same after leaching the core with NH3. The inset of figure b shows an expanded view of

a TiO2 shell. Reprinted from ( D. S. Koktysh, X. Liang, B.-G. Yun, I. Pastoriza-Santos, R. L.

Matts, M. Giersig, C. Serra-Rodriguez, L. M. Liz-Marzan, N. A. Kotov, Adv. Funct. Mater.,

2002, 12, 255). Copyright (2002) Wiley-VCH.

Fig. 9.18: Schematic showing the stability of core-shell nanoparticles with intense laser fluences.

Fig. 9.19: Optical limiting responses of Au@TiO2 and Au@ZrO2 core-shell nanoparticles using

the Z-scan technique. Inset shows the Z-scan curve of Ag@ZrO2 system. Reprinted with

permission from ( R. T. Tom, A. S. Nair, N. Singh, M. Aslam, C. L. Nagendra, R. Philip, K.

Vijayamohanan, T. Pradeep, Langmuir, 2003, 19, 3439). Copyright (2003) American Chemical

Society.