Templating of Metal Oxides by Electrodeposition

The aim of this part of the study was to use the voided DG films, typically prepared 

Parts of this chapter were previously published and are reprinted/adapted with permission from American Chemical Society and WILEY-VCH Veriag GmbH, Copyright 2013 [1, 2]. 

Scherer, Double-Gymid-Structured Functional Materials, Springer Theses, DOl 10.1007/978-3-319-00354-2 5, 

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Fig. 5.1 Templated electrodeposition of metal oxides. (1) The electrochemical refiUing process starts at the FTO surface and progresses trough the voided DG channels. The deposition process is restricted to areas that are not covered by SU-8, thereby creating a visible design pattern in the electroplated V2O5. (2) Removal of the styrenic template yields the free-standing, mesoporous DG-structured metal oxide network...

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. 

EISA. The mechanism in each case has been the subject of much research and the current understanding of each mechanism is described below. The other two methods to produce mesoporous templated materials are electrodeposition,which has been successfully used to produce surfactant templated porous metal films from high concentration surfactant solutions, and nanocasting, where a surfactant templated silicate is used as a sacrificial template to generate further porous materials by coating the silica structure in another oxide or carbon precursors. The second material is sintered or solidified, and the silicate removed by HE or high pH solvent wash. This is discussed further in Section 2.10. 

Electrochemical methods for the preparation of anode electrocatalysts for DAFCs involve either the electrodeposition of one metal at a time, eventually followed by the electrodeposition of other metals, or the contemporaneons electrodeposition of two or more metals. Highly ordered Pd nanowires arrays (Fig. 5) have been prepared by template-electrodeposition on glassy carbon electrodes, while cyclic potential sweep techniqnes have been used to prepare Pd thin films on polyciystalline Pt or An substrates. Ni-Pd electrodes for methanol oxidation have been prepared by electrodeposition onto titaninm discs nsing a PdCl2/NiS04-7H20 bath." ... 

An interesting variation on template deposition is to self-assanble ordered nanostructures (e.g., surfactants) and microstructures (e.g., polystyrene or Si02 beads) on the surface of an electrode and then electrodeposit into the self-assembled pores. The order in the resulting nanostructure is imposed by the self-assembled layer, not by the substrate. Schwartz and coworkers have extended this idea to the use of crystalline protein masks to produce ordered nanostructures of metals (such as Ni, Pt, Pd, and Co) and metal oxides (such as Cu20). Braun and coworkers have used the electrodeposition of materials into self-assembled colloidal crystals or silica or polymer opals. The template is then removed (see Figure 17.11) to produce an inverse opal. This type of templating produces periodic microstructures that can be used to produce functional photonics. Figure 17.11 shows the production of CdSe and Ni inverse opals by electrodeposition into a colloidal crystal with subsequent removal of the colloidal crystal template. ... 

By sequential electrodeposition of different metals into a template such as anodic aluminum oxide (AAO), multisegmented metaUic nanorods can be synthesized. Examples of multisegmented metallic nanoiods synthesized by this means include Pt-RuNi-Pt-RuNi-Pt (114), Pt-Ru, Pt-Ru-Pt and their analogs (115), Ag-Au-Ag (116), Ni-Pt, Ni-Pt-Ni and their analogs (117). The synthesis of multisegmented Pt-Ru nanorods by template electrochemical deposition is briefly described below. 

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