Cobalt electrochemical polymerization

The PANl/porphyrin nanocomposites have been fabricated using the similar approach [110,111]. To extend the functionalities of the nanocomposites, metalloporphyrin has also been used as template to synthesize CP/ cobalt porphyrin nanocomposites through electrochemical polymerization. Similar to porphyrin, cobalt porphyrin can also form J-aggregates, and many rod-like structures have been observed after dispersing their aqueous solution onto freshly cleaved mica. An electrochemical polymerization forming PPy was templated by J-aggregates of cobalt porphyrin to form PPy/cobalt porphyrin nanocomposites in the presence of cobalt porphyrin in the pyrrole solution [112]. Ihe diameter of the as-synthesized PPy/cobalt porphyrin composite nanorods was aroimd 50 nm when the cobalt porphyrin solution was ultrosonicated for at least three hours before the electropolymerization of pyrrole on the electrode surface. In the presence of cobalt porphyrin, the composite nanorods exhibited excellent elec-trocatalytic activity. 

Several reports were published on the PT/metal hybrids or PT/inorganic nanocomposites. Novel bithiophene with a pendant fullerene substituent was synthesized by electrochemical polymerization [350]. It was revealed that a photoinduced electron was transferred from the donor cable (PT) to the pendant acceptor cable (fullerene moieties). On the other side, it was demonstrated that a highly conducting cobalt selen-PT hybrid material catalyzed... 

Many perfluoroaUphatic ethers and tertiary amines have been prepared by electrochemical fluorination (1 6), direct fluorination using elemental fluorine (7—9), or, in a few cases, by fluorination using cobalt trifluoride (10). Examples of lower molecular weight materials are shown in Table 1. In addition to these, there are three commercial classes of perfluoropolyethers prepared by anionic polymerization of hexafluoropropene oxide [428-59-1] (11,12), photooxidation of hexafluoropropene [116-15-4] or tetrafluoroethene [116-14-3] (13,14), or by anionic ring-opening polymeriza tion of tetrafluorooxetane [765-63-9] followed by direct fluorination (15). 

Dloxygen reduction electrocatalysis by metal macrocycles adsorbed on or bound to electrodes has been an Important area of Investigation (23 ) and has achieved a substantial molecular sophistication in terms of structured design of the macrocyclic catalysts (2A). Since there have been few other electrochemical studies of polymeric porphyrin films, we elected to inspect the dloxygen electrocatalytic efficacy of films of electropolymerized cobalt tetraphenylporphyrins. All the films exhibited some activity, to differing extents, with films of the cobalt tetra(o-aminophenylporphyrin) being the most active (2-4). Curiously, this compound, both as a monomer In solution and as an electropolymerized film, also exhibited two electrochemical waves... 

An aluminum electrode modified by a chemically deposited palladium pen-tacyanonitrosylferrate film was reported in [33]. Vitreous carbon electrode modified with cobalt phthalocyanine was used in [34]. Electrocatalytic activity of nanos-tructured polymeric tetraruthenated porphyrin film was studied in [35]. Codeposition of Pt nanoparticles and Fe(III) species on glassy-carbon electrode resulted in significant catalytic activity in nitrite oxidation [36]. It was shown that the pho-tocatalytic oxidation at a Ti02/Ti film electrode can be electrochemically promoted [37]. 

In the most important series of polymers of this type, the metallotetraphenylporphyrins, a metalloporphyrin ring bears four substituted phenylene groups X, as is shown in 7.19. The metals M in the structure are typically iron, cobalt, or nickel cations, and the substituents on the phenylene groups include -NH2, -NR2, and -OH. These polymers are generally insoluble. Some have been prepared by electro-oxidative polymerizations in the form of electroactive films on electrode surfaces.79 The cobalt-metallated polymer is of particular interest since it is an electrocatalyst for the reduction of dioxygen. Films of poly(trisbipyridine)-metal complexes also have interesting electrochemical properties, in particular electrochromism and electrical conductivity.78 The closely related polymer, poly(2-vinylpyridine), also forms metal complexes, for example with copper(II) chloride.80... 

Cobalt phthalocyanines, PhtCo, can be readily reduced either with hydrazine,183 with sodium boro-hydride,184 or electrochemically.185 186 In the latter case, PhtCo can undergo five sequential reductions to the pentaanion. All of the negatively charged species have distinct visible spectra. The visible spectrum of PhtCo1 is independent of counterion or solvent. When radical polymerization of methacrylate is conducted in the presence of amides such as dimethylformamide, hexamethylphosphorus tria-... 

MnO has been also coated with PANl to improve its electrochemical performance. Shin et al found that the cobalt-intercalated layered manganese oxide (CLMO) displayed the excellent cyclability over 40 cycles, although it exhibited a low discharge capacity (143 mA h g at 40 mA g current density) [51]. After chemical oxidative polymerization of aniline... 

It has been found that the O2 reduction currents are directly proportional to the amount of catalyst present when the catalyst is adsorbed on the electrode surface indicating that the reaction is first order in the surface concentration of catalyst. This is not tme for cases where the catalyst is incorporated to the surface by vapor deposition or when the eatalyst is deposited from solutions and the solvent is completely evaporated . An explanation for this observation is that when the catalyst is deposited by vapor deposition or from complete evaporation of solutions, multilayers are formed, and the metal active centers are not all completely accessible to O2. This is also the case for polymerized multilayers of cobalt tetraamino phthalocyanines, where it has been shown that only the outermost layer was active for the reduction of O2 . Scherson et al. have reported that when (FeTMPP)20 is deposited on a porous support, 30% of the amount deposited is found to be electrochemically active . Anson et have found that for the case of CoPc(CN)i6 and CoPcFie that were deposited from solutions where the solvent was completely evaporated, again it was found that only 30% of the amount deposited was electrochemically active. It was concluded that only those molecules that are attached to the surface of the electrode are active... 

Thin films of cr-bonded tetraazaannulenic complexes of cobalt were electrochemically synthesized. From a potential cycling applied to a platinum electrode in an electrolytic solution containing the monomer, the electrodeposition process occurred via a 6-6 polymerization of the monomers . Also, the electrochemical homopolymerization of M-78 (M = Ni, Cu) derivatives was thoroughly investigated , some of which were functionalized at the y-position . 

Lelj, F., G. Morelli, G. Ricciardi, and A. Rosa (1990). The electrochemical behaviour and electrooxidative polymerization of tetraazannulenic alkyl- and aryl-cobalt complexes. Inorg. Chim. Acta 176, 189-194. 

The sensitivity and selectivity of the polymeric porphyrin depends not only on the potential of NO to oxidize but also on the fast process of electrochemical NO oxidation, which generates the high current. In addition, surface effects, axial ligation to the central metal in the porphyrin, nature of the central metal (iron > nickel > cobalt zinc, copper), gas permeability through sensor layer(s), and fast removal of NO" " by Nafion are all important in promoting fast and selective oxidation... 

So far, CMK-5 carbons have been much less explored than CMK-3. One possible reason is the difficulty of finding suitable precursors that permit a strict control of the pore wall thickness to obtain stable carbon replicas. There are reports indicating the possibility of preparing CMK-5 with controlled pore wall thickness by using different methods of furfuryl alcohol polymerization and ferrocene as carbon precursors. Also, there are reports on the incorporation of highly dispersed nanoparticles of platinum " and cobalt into CMK-5 to enhance its electrochemical and... 

Peng QY, Guarr TF (1994) Electro-oxidation of hydrazine at electrodes modified with polymeric cobalt phthalocyanine. Electrochem Acta 39 2629-2632... 

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