Seed-mediated growth

Preparation and growth mechanism of gold nanorods (NRs) using seed-mediated growth method. 

Scheme 1. Schematic representation of seed-mediated growth of the particles. (Reprinted from Ref [35], 2001, with permission from American Chemical Society.)...

Lu LH, Wang HS, Zhou YH, Xi SQ, Zhang HJ, Jiawen HBM, Zhao B (2002) Seed-mediated growth of large, monodisperse core-shell gold-silver nanoparticles with Ag-like optical properties. Chem Commun, pp 144-145... 

Gold nanorods (GNRs) can be produced with reasonable yields through several approaches such as template-based methods [158, 159], electrochemical methods [160, 161], or via seed-mediated wet chemistry methods. Due to their simplicity and the ease of nanorod size and shape control, the latter, seed-mediated growth methods in the presence or absence of Ag+ ions are commonly preferred [162-165],... 

Scheme 2 Schematic of a seed-mediated, surfactant-assisted gold nanorod synthesis. The small black dots represent Ag+ ions, the orange stars are CTAB molecules forming micelles, the yellow circles and green squares are AuCLf and AuC12 , respectively, forming complexes with the CTAB micelles. Freshly-prepared gold nanoparticle seeds are injected into the growth solution in the final step of the nanorod synthesis [166]. (Copyright 2008, American Chemical Society)...

Johnson, C. J., Dujardin, E., Davis, S. A., Murphy, C. J. Mann, S. Growth and form of gold nanorods prepared by seed-mediated, surfactant-directed synthesis. J. Mater. Chem. 12, 1765-1770 (2002). 

Jana, N. R., Gearheart, L. Murphy, C. J. Seed-mediated growth approach for shape-controlled synthesis of spheroidal and rod-like gold nanoparticles using a surfactant template. Adv. Mater. (Weinheim, Ger.) 13, 1389-1393 (2001). 

Nikoobakht, B. and El-Sayed, M. A. (2003). Preparation and growth mechanism of gold nanorods (NRs) using seed-mediated growth method. Chem. Mater. 15 1957-1962. 

Seed-Mediated Growth Approach to the Synthesis of Inorganic Nanorods and Nanowires 287 9.2... 

Fig. 9.2. Cartoon showing the seed-mediated growth approach to the synthesis of metallic nanorods of controllable aspect ratio. In the first step, metal salts are reduced with sodium borohydride, a strong reducing agent, to metal nanospheres ( seeds ) that are 3-4 nm in diameter. In the subsequent growth steps.

Fig. 9.3. Transmission electron micrograph of gold nanorods, prepared by the seed-mediated growth method in water, in the presence of CTAB. Scale bar = 100 nm.

Our seed-mediated growth approach has been successful for the synthesis of gold nanorods, with diameters of ca. 20 nm and aspect ratios from 2 to 20, in a controllable fashion (Figure 9.3). For silver, we have been able to make both short nanorods (aspect ratio 4) and long nanowires (aspect ratios 50-350) in the case of nanowires the level of control we have is more limited. 

In the case of gold nanorods prepared in aqueous solution by the seed-mediated growth method, we have performed high-resolution transmission electron microscopy (HRTEM) and electron diffraction experiments as a function of growth time to crystallographically characterize the nanorods [45]. It is well-known that for the face-centered cubic (fee) structure of gold, the (111) face is the most stable, close-... 

On the other hand, liquid phase deposition (LPD) has been demonstrated as a flexible wet chemical method for preparing metal oxide nanostructured films on electrode surfaces. By the LPD process, electroactive titanium dioxide (Ti02) films were prepared on graphite, glassy carbon and ITO. The electrochemical properties of such LPD Ti02 films were dependent upon the film thickness controlled by the deposition time. The LPD technique was easily combined with other techniques, e.g., seed-mediated growth, which could provide metal/metal oxide composite nanomaterials. Moreover, hybrid nanostructured films were facilely obtained by doping dyes, surfactants and other... 

In this chapter, we would like to introduce two wet chemical methods, namely a seed-mediated growth approach and a liquid phase deposition process, which have been successfully utilized to modify electrode surfaces with gold nanoparticles or Ti02 nanostructured films. Because both methods are soft , the particle size or film thickness is... 

Seed-Mediated Growth of Gold Nanoparticles on Electrode Surfaces... 

Fabrication of Gold Nanoparticle-Modified Electrodes with Seed-Mediated Growth Approach... 

Figure 1. Schemes of the seed-mediated growth method (A) for preparing Au nanorods, and (B) for modifying an ITO surface with gold nanoparticles.

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