Template deposition

We used polyelectrolyte multilayer formed from polyallylamine hydrochloride (PAH) and PSS successfully for templating deposition of colloidal particles, as displayed in Fig. 12. The wavelength of the wrinkles was adjusted by the number of polyelectrolyte deposition cycles and, accordingly, single lines of particles or double lines, as well as other geometries, could be achieved [70],... 

Each of the electrode geometries shown in Fig. 1 can be arranged in groups to form array electrodes, examples of which are shown in Fig. 2. The behavior of array electrodes depends on the ratio of the diameter of the individual electrode features to the spacing between electrode features as demonstrated in Fig. 3. Arrays may be made using lithographic procedures or electrochemical or electroless template deposition methods. 

The gradually increase in film thickness was controlled by monitoring the deposition time rather than the charge passing through the cell because of the reason mentioned in Sect. 5.1.1.2. Subsequently, the vanadium oxide films were rinsed with deionized water, dried, and in case of templated deposition were freed of the styrenic scaffold by dissolution in toluene. 

Sacrificial template Deposition Mesoporous Huang etal. (2013) 2013... 

The first part of this section focuses on the main characteristics and fabrication techniques used for obtaining templating membranes and depositing metal nanostructures by suitable electroless and elecuochemical procedures. Methods such as sol-gel (10-12) or chemical vapor deposition (10, 13), which have been used primarily for the template deposition of carbon, oxides, or semiconducting-based materials, will not be considered here in detail. The second part of the section focuses on the electrochemical properties of the fabricated nanomaterials with emphasis on the characteristics and applications of nanoelectrode ensembles (NEEs). 

Electrochemical deposition of metals in the pores of templating membranes requires that one side of the membrane be in direct contact with a metallic layer. This can be produced by plasma or vacuum deposition of a metal layer on one side of the membrane (25) and requires that the membrane film be robust enough to tolerate this kind of manipulation. The thickness of the conductive layer is typically 100-1000 nm (45-47). The metal which produces the conductive layer can be the same or different from the one that will provide the final template structure. In electrochanical template deposition, the coated film is placed in an electrochemical ceU where the template membrane acts as the cathode and a counter electrode is the anode. The deposition can be carried out under galvanostatic or... 

Figure 16.2.5 Electrochemical template deposition of metals (A) scheme of the electrochemical cell and (B) sequence of the growth of the template for the preparation of single metal continuous nanowires (sequences 1-4) or segmented nanoparticles (sequences 1, 2, 5, and 6). Detailed steps (1) metal sputtering to provide a conductive layer for the subsequent electrodeposition (2) electrodeposition of the same metal to form the fibers (3) growth of the fibers (4) etching of the template (5) electrodeposition of another metal (6) composite structure after the etching of the foundation metal. Part (B) redrawn with permission from reference (25).

Conditions and materials used for the electrochemical template deposition of metals... 

Pomfret, M. B. Brown, D. J. Epshteyn, A. Purdy, A. P Owrutsky, J. C. Electrochemical template deposition of aluminum nanorods using ionic liquids. Chem. Mater. 2008, 20, 5945-5947. 

The deposition of nanowires and nanotubes into tanplates was pioneered by Martin. In template deposition, the materials are deposited into nanoporous manbranes, such as anodized aluminum or track-etch polymers. The nanoporous membranes function as nanosized beakers that constrain the crystal growth. Figure 17.10 shows TEM micrographs of Au nanowires with a diameter of 70 nm and polypyrrole nanotubes with an outside diameter of 90 nm and an inside diameter of 20-30 nm that were eleclrodeposited into an alumina nanoporous tanplate. ... 

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. ... 

In ccMitrast to the electrochemical template deposition, in the electroless method the metal layer grows from the catalytic nuclei, which are located on the pore walls, towards the center of the pores. For this reason it is possible to stop the deposition at short times in order to obtain hollow tubes instead of nanowires. This procedure allows to obtain microfiltratiOTi membranes with golden pores. Also other metals, such as Cu, Pd and Ni-P can be deposited in polycarbonate templates by electroless deposition. In this case a suitable procedure for the desired metal has to be applied. 

---