Electrodeposition metal nanoparticles

Another approach to controlling the eiectrodeposition of nanoparticles on pristine CNTs surfaces was again reported by Day and co-workers [97]. The authors electrodeposited metal nanoparticles on pristine CNTs networks using a microcapillary electrochemical cell. Figure 14.12 illustrates a schematic of the microcapillary experimental setup. In their experiment, a microcapillary filled with the metal solution and a reference electrode is placed in contact with CNTs network, which is connected as a working electrode. Eiectrodeposition is promoted by applying a potential between the CNT network and the reference electrode. It was shown that by controlling the deposition potential and time, the number density, distribution, and nanoparticle size able to be controlled. 

In general, metal nanoparticles are obtained via reduction of metal complexes, such as metal chlorides, by chemical agents (chemical reduction), or by electrons (electrodeposition). Hybrids of metal oxides are obtained by oxidation, network formation or precipitation of precursors such as metal nitrates and acetates [144]. 

Deposition of metals may lead to well dispersed metal nanoparticles, as discussed in the previous section, but also to special metal structures. Using a Xi02 nanotube array prepared by anodic oxidation as a template and electrodepositing An onto the template. An nanonets could be prepared. 

Common methods for the fabrication of metallic nanoparticle arrays are electron beam lithography, photolithography, laser ablation, colloidal synthesis, electrodeposition and, in recent time, nanosphere lithography for which a monodisperse nanosphere template acts as deposition mask. A review on advances in preparation of nanomaterials with localized plasmon resonance is given in [15]. 

Besides these chemical methods, electrochemical techniques are of interest. This is because the electrodeposition is a convenient and fast method for the preparation of metallic nanoparticles on large areas of conductive substrates. However, for precise and systematic investigation of the nanoparticle properties control of the particle size, form and distribution is necessary. From this point of view, the classical electrodeposition technique from solution is not so successful, as the homogeneity in particle size and spatial particle distribution is presumably disappointing in comparison to the invasive tip-directed SPM routes [21] or deposition techniques into nanotemplates. 

His research group successfully started extensive investigations on the electrodeposition of silver [24—26] and gold [26] nanoparticles on graphite surfaces. Combined with Brownian dynamic simulations for the growth of metal nanoparticle ensembles [22, 23], the work focused on the development of nontemplate, electrochemical routes to dimensionally uifiform metal structures. 

Different electron-conducting polymers (polyaniline, polypyrrole, polythiophene) are considered as convenient substrates for the electrodeposition of highly dispersed metal electrocatalysts. The preparation and the characterization of electronconducting polymers modified by noble metal nanoparticles are first discussed. Then, their catalytic activities are presented for many important electrochemical reactions related to fuel cells oxygen reduction, hydrogen oxidation, oxidation of Cl molecules (formic acid, formaldehyde, methanol, carbon monoxide), and electrooxidation of alcohols and polyols. 

Figure 1. SEM images of different electrodeposited metal oxide nanoparticles Ti02 nanotube arrays grown on Ti substrate(a) cobalt oxide nanoparticles onto glassy carbon electrode (b) nickel oxide nanoparticles(c) and zinc oxide nanoparticles Reproduced from references [ 138],[ 102],[ 137] and [135] with permission from Elsevier.

Metal nanoparticles can also be synthesized at a polarized liquid liquid interface. As a matter of fact, the first experimental evidence for heterogeneous electron transfer at an externally biased ITIES featured the electrodeposition of copper and silver [162]. More recently, Cheng and Schiffrin [163] demonstrated the formation of gold nanoparticles at the ITIES by reducing tetraoctylammonium tetrachloroaurate dissolved in DCE by aqu-... 

Electrodeposition is another method used to produce metal nanoparticles on CNTs. This process was performed in a two electrode arrangement in a solution containing the CNTs with HAUCI4, K2PtCl4, or (NH4)2PdCl4. As a result of this study, Au, Pt, and Pd nanoparticles were deposited on the CNTs by controlling the deposition potential, duration of the pulse, and the concentration of the metal salt in the electrochemical system (Quinn et al. 2005). 

In the E/C synthesis, the first step in which metal nanocrystals are deposited on the substrate is critical. The semiconductor particles grow from the metal particles on a particle-by-particle basis (i.e. each metal particle is chemically transformed to the corresponding semiconductor). The size and size distribution, therefore, in the first step determine the final size of the semiconductor particles. For that reason, it is important to achieve an understanding of the growth mechanism of the metal nanocrystal deposition. Penner and associates studied the electrodeposition of various metal nanoparticles (Ag, Pt, Zn, Cu, Cd) mainly onto basal plane-oriented graphite and also onto Si electrodes [6-11]. The depositions were carried out from dilute aqueous solutions of metal ions using a potentiostatic pulse regime. A short (typically tens of ms) potential pulse was applied followed by open[Pg.174]

Metal nanoparticles can also be electrodeposited onto a CP modified electrode to obtain nanocomposites. The number, size and distribution of metal particles can be controlled by the conditions of electrochemical deposition. The pulse potentiostatic technique results in an efficient dispersion of Pt particles in the polymer matrix. 

Pt Clg], and Cu, respectively, resulting in the individual metal nanoparticles, the size and morphology, and the relative ratio of the crystalline facets of which are unique and different from those of the corresponding nanoparticles electrodeposited conventionally. Some factors controlling the disproportionations and their mechanisms are also discussed. A disproportionation reaction-driven electroless deposition in RTILs is expected as a promising procedure to develop novel nanostructures such as electrocatalysts. 

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Van Dijk MA, Tchebotareva AL, Orrit M, Lippitz M, Berciaud S, Lasne D, Cognet L, Lounis B (2006) Absorption and scattering microscopy of single metal nanoparticles. Phys Chem Chem Phys 8 3486-3495 Vasan HN, Rao CNR (1995) Nanoscale Ag-Pd and Cu-Pd alloys. J Mater Chem 5 1755-1757 Walter EC, Ng K, Zach MP, Penner RM, Favier F (2002a) Electronic devices from electrodeposited metal nanowires. Microelectron Eng 61-62 555-561... 

Recently, electrodeposition has been proved to provide a versatile method for producing metal nanoparticles and nanowires in the pores of polycarbonate, mica, and aluminum oxide templates [33-36]. In this case, the template imparts size control. Behm et al. obtained... 

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