Metal oxide synthesis electrochemical deposition

According to Ref. [12], template for synthesis of nanomaterials is defined as a central structure within which a network forms in such a way that removal of this template creates a filled cavity with morphological or stereochemical features related to those of the template. The template synthesis was applied for preparation of various nanostructures inside different three-dimensional nanoporous structures. Chemically, these materials are presented by polymers, metals, oxides, carbides and other substances. Synthetic methods include electrochemical deposition, electroless deposition, chemical polymerization, sol-gel deposition and chemical vapor deposition. These works were reviewed in Refs. [12,20]. An essential feature of this... 

In 1963 Dr. Danbk joined the Institute of Inorganic Chemistry of the Slovak Academy of Sciences in Bratislava, of which he was the director in the period 1991-1995. His main field of interest was the physical chemistry of molten salts systems in particular the study of the relations between the composition, properties, and structure of inorganic melts. He developed a method to measure the electrical conductivity of molten fluorides. He proposed the thermodynamic model of silicate melts and applied it to a number of two- and three-component silicate systems. He also developed the dissociation model of molten salts mixtures and applied it to different types of inorganic systems. More recently his work was in the field of chemical synthesis of double oxides from fused salts and the investigation of the physicochemical properties of molten systems of interest as electrolytes for the electrochemical deposition of metals from natural minerals, molybdenum, the synthesis of transition metal borides, and for aluminium production. 

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. 

It is the aim of this chapter to give an overview on both chemical and electrochemical techniques for producing metallic-particle-based CP nanocomposite materials and to outline the progress made in this field. The various synthetic approaches are organized in such a way as to present first those involving metal particle deposition in the course of polymerization, and subsequently post-polymerisation procedures that involve chemical, electrochemical, or adsorption processes (Figure 7.1). Well-established approaches, along with some newly developed techniques will be discussed, with special emphasis on those that are still underdeveloped. Synthesis of metal oxide particle-based CP composites (see e.g. [8]), as well as modification of CPs with transition-metal complexes (see e.g. [5]) remain outside the scope of this chapter. 

For the third process, conducting polymers and metal oxides can be simultaneously deposited onto carbonaceous scaffolds by using CNTs or graphene as frameworks during chemical process or electrodes in the electrochemical procedure. This is similar to the one-pot synthesis of binary composites. Besides sequential compositing, ternary composites can also be fabricated by a one-step electrochemiccd deposition to reach desirable porous architectures due to its simplicity and reliability. It was proposed to prepare unique PPy/reduced GO/CNT ternary composites, where reduced GO, CNT, and PPy were electro-deposited simultaneously to construct a three-dimensionally highly porous film electrode (Dingetal., 2012). 

Dierstein A, Natter H, Meyer F, Stephan HO, Kropfl C, HempehnannR. Electrochemical deposition under oxidizing conditions (EDOC) a new synthesis for nanocrystalline metal oxides. Scripta Materiala 2001 44(8) 2209-12. 

Several methods for the incorporation of catalysts into microreactors exist, which differ in the phase-contacting principle. The easiest way is to fill in the catalyst and create a packed-bed microreactor. If catalytic bed or catalytic wall microreactors are used, several techniques for catalyst deposition are possible. These techniques are divided into the following parts. For catalysts based on oxide supports, pretreatment of the substrate by anodic or thermal oxidation [93, 94] and chemical treatment is necessary. Subsequently, coating methods based on a Uquid phase such as a suspension, sol-gel [95], hybrid techniques between suspension and sol-gel [96], impregnation and electrochemical deposition methods can be used for catalyst deposition [97], in addition to chemical or physical vapor deposition [98] and flame spray deposition techniques [99]. A further method is the synthesis of zeoUtes on microstructures [100, 101]. Catalysts based on a carbon support can be deposited either on ceramic or on metallic surfaces, whereas carbon supports on metals have been little investigated so far [102]. 

Electrochemical deposition (ECD) has been a technique for material synthesis since Luigi Brugnatelli first electroplated gold in 1805. After this historic achievement, ECD has advanced to include the deposition of other metals and alloys through the use of earth-abundant metal salts. In more recent times, metal oxides," -" metal sulfides," semiconductors, - and conductive... 

Conducting polymers can be prepared by chemical or electrochemical techniques. Electrochemical synthesis provides easier routes when compared with chemical synthesis and allows control over film formation, especially relevant if polymers are required as thin films deposited on the surface of metallic substrates. However, electrochemically synthesized polymers are usually more porous, a feature that requires consideration when a barrier effect is necessary. Another important aspect in the corrosion field is that the application of potential/current necessary to promote electropolymerization may accelerate dissolution (corrosion) of the metal. In some cases, an oxide pre-layer is deposited between the metal and the polymer to promote adhesion and hinder metal dissolution during the electropolymerization process (Tallman et al., 2002 Spinks et al., 2002). Alternatively, the application of layered coatings based on different conducting polymers can be a strategy to overcome the problem of metal dissolution. In the work of Lacroix et al. (2000), a layer of PPy was firstly deposited on zinc and mild steel in neutral conditions, followed by deposition of PANi in an acidic medium, because the direct deposition of PANi on those metallic substrates was not possible in an acidic medium, causing dissolution of the metal. 

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