Co-electrodeposition

Conducting polymer composites have also been formed by co-electrodeposition of matrix polymer during electrochemical polymerization. Because both components of the composite are deposited simultaneously, a homogenous film is obtained. This technique has been utilized for both neutral thermoplastics such as poly(vinyl chloride) (159), as well as for a large variety of polyelectrolytes (64—68, 159—165). When the matrix polymer is a polyelectrolyte, it serves as the dopant species for the conducting polymer, so there is an intimate mixing of the polymer chains and the system can be appropriately termed a molecular composite. 

The electrodeposited Bi2Sr2CaiCu2Ox (BSCCO) precursor films were obtained by co-electrodeposition of the constituent metals using nitrate salts dissolved in DMSO solvent. The electrodeposition was performed in a closed-cell configuration at room temperature ( 24°C). The cation ratios of the electrodeposition bath were adjusted systematically to obtain BSCCO precursor compositions. A typical electrolyte-bath composition for the BSCCO films consisted of 2.0-g Bi(N03)3-5H20,1.0-g Sr(N03)2, 0.6-g Ca(N03)2-4H20, and 0.9-g Cu(N03)2-6H20 dissolved in 400 mL of DMSO solvent. The substrates were single-crystal LAO coated with 300 A of Ag. 

Variants of preparation have been proposed [135, 248] including sintering [391] or co-electrodeposition of the precursors [138, 407], and aluminization of the surface of Ni at high temperature whose nature has a definite effect on the resulting electrocatalytic activity [408]. The main features of Raney Ni have been evaluated, including the pore size distribution and the real surface area [93, 135]. It has been found that the composition of the precursor alloys and their particle size have important influence on the adsorption properties of the resulting Raney metal, hence on its electrocatalytic properties [409]. 

Like silver, Co(III) is also a powerful oxidizing agent with E° = 1.82 V. Co(II) in HNO3 has been employed to degrade different organic compounds [70,71,73,74] by using separators to prevent Co electrodeposition. In acidic aqueous media, the oxidation of Co(II) to Co(III) has less than 100% current efficiency because it occurs at a more positive potential than water. Cobalt has the advantage over silver in that cobalt chloride complexes are... 

It is helpful for the electrochemical degradation ability by getting a uniform layer on base metals. Electrodeposition is convenient and is an effective way to realize this. Sb and Sn metals can be prepared either by co-electrodeposition together or by a sequencing electrodeposition. We developed a sequencing electrodeposition method which is more useful for more uniform and more effective layers. 

Applications. A biotinylated GOX-based biosensor was developed based on a new electropolymerized material consisting of a pol3rp3uidyl complex of ruthenium(II) functionalized with a pyrrole group [90]. Because histidine, lysine and arginine functions also coordinate Os /Os , biosensors based on co-electrodeposited GOX, HRP, soybean peroxidase (SBP) and laccase with redox Os /Os polymer have been developed [89]. A metal chelate formed by nickel and nitrilotriacetic acid was used to modify a screen-printed electrode surface. The functionalized support allowed stable attachment of acetylcholinesterase and the resulting biosensor was used for sensitive detection of organophosphorus insecticides [91]. This method is attractive because it ensures a controlled and oriented enzyme immobilization, considerably improving the sensitivity and the detection limit. 

Figure 7.8 A typical one-step co-electrodeposition method for the synthesis of GO/PPy nanocomposites. Reprinted with permission from Ref. [91]. Copyright 2012, Royal Society of Chemistry.

Co-electrodeposition should occur. It requires a certain bath. 

Fig. 7.21 Dark-field TEM images of the Co-Ni electrodeposits containing 80 at. % Co, electrodeposited with 0.05 g dm (a) an [25] with kind permission from Springer)...

In Fig. 8.1a are shown polarization curves corrected for IR drop for the processes of Co, Ni, and Co-Ni alloy powder electrodeposition from 1 M (NH4)2S04 + 0.7 M NH4OH containing supporting electrolyte. Their shape of aU polarization curves is identical, characterized with two inflection points, A and B. For Co electrodeposition, sharp increase of current occurs at about —1.19 V versus Ag/AgCl, while for Ni electrodeposition, this phenomenon is moved to more negative potentials... 

Typical polarization curves with (1) and without IR drop correction (2) are presented in Fig. 2.24. While recording polarization curves with and without IR drop correction for all investigated alloy powders electrodeposition, almost identical difference between curves with (1) and without IR drop correction (2) for all supporting electrolytes, as well as for all investigated systems is obtained. In Fig. 2.24 is shown an example for Co electrodeposition from ammonium sulfate containing supporting electrolyte [90, 91]. 

Comparing polarization curves (/tot) recorded onto GC and Co electrodes (Fig. 2.35) one can see that the electrodeposition process onto Co electrode commences at more positive potentials, while the current density of the second inflection point, as well as the current density at potentials more negative than that point, is smaller. Such behavior is reasonable to expect since the overvoltage for Co electrodeposition should be higher for GC than for Co electrodes, while at the same time the increase of the real surface area onto Co... 

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The electrochemical behaviour of LiCl-KCl eutectic+ LaCl3, CeCl3 and NdCl3 (0.5 wt%) with various concentrations of LiF was also evaluated. By differential pulsed voltammogram using tungsten electrode, the broad peak of electro-reduction which corresponds to the co-electrodeposition of all rare earths could be identified as well as a similar peak which corresponds to the electro-reduction into Nd ". Therefore, if the potential constant electrolysis can be performed at a potential close to reduction into Nd " ", this fact implies that it is possible to enrich the neodymium cation around the cathode. 

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