Tom, Renjis T. and Nair, A. Sreekumaran and Singh, Navinder and Aslam, M. and Nagendra, C. L. and Philip, Reji and Vijayamohanan, K. and Pradeep, T. (2003) Freely Dispersible Au@TiO2, Au@ZrO2, Ag@TiO2, and Ag@ZrO2 Core−Shell Nanoparticles: One-Step Synthesis, Characterization, Spectroscopy, and Optical Limiting Properties. Langmuir,, 19 (8). pp. 3439-3445. ISSN
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Official URL: http://pubs.acs.org/doi/abs/10.1021/la0266435
We report a one-step route for the synthesis of Au@TiO2, Au@ZrO2, Ag@TiO2, and Ag@ZrO2 particles in nanometer dimensions, with controllable shell thickness. This scalable procedure leads to stable and freely dispersible particles, and bulk nanocomposite materials have been made this way. The procedure leads to particles of various morphologies, with a crystalline core in the size range of 30−60 nm diameter and an amorphous shell of 3 nm thickness in a typical synthesis. The core diameter and shell thickness (in the range of 1−10 nm) can be varied, leading to different absorption maxima. The material has been characterized with microscopic, diffraction, and spectroscopic techniques. The metal particle growth occurs by the carbamic acid reduction route followed by hydrolysis of the metal oxide precursor, resulting in the oxide cover. The particles could be precipitated and redispersed. The shell, upon thermal treatment, gets converted to crystalline oxides. Cyclic voltammetric studies confirm the core−shell structure. The E1/2 value is 0.250 V (ΔE ≈ 180 mV) for the quasi-reversible Agm/Agm+ couple and 0.320 V (ΔE ≈ 100 mV) for the Aun/Aun+ couple for Ag and Au particles, respectively. Adsorption on the oxide surface blocks electron transfer partially. Nonlinear optical measurements in solutions show that these materials are strong optical limiters with a high laser damage threshold.
|Subjects:||Physical Science > Nanophysics|
Physical Science > Nano objects
Material Science > Nanochemistry
Material Science > Nanostructured materials
|Divisions:||Faculty of Engineering, Science and Mathematics > School of Physics|
Faculty of Engineering, Science and Mathematics > School of Chemistry
|Deposited On:||11 Aug 2009 07:19|
|Last Modified:||11 Aug 2009 07:19|
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