Electrode preparation methods

Uchida, M., Aoyama, Y, Eda, N., and Ohta, A. New electrode preparation method for polymer electrolyte fuel cells. Journal of the Electrochemical Society 1995 142 463-468. 

To achieve a catalytic layer on base materials is the core process for DSA-electrode fabrication. To ensure the layer stability, it is important to try to make the layer better adhesion with the base surface. We have tried several methods in the electrode preparation, including pretreatment, pyrolysis technologies, and electrodeposition. Till now, our research revealed that the electrode service life and the behaviors have been influenced by the electrode preparation methods and technological factors. 

Electrode preparation methods significantly affect fuel cell performance. A variety of methods have been developed. For example, Bevers et al. [17] produced electrodes using a simple and less costly procedure, a modified rolling technique, formerly used in the production of electrodes for alkaline fuel cells and batteries. With these new electrodes, the same power output was obtained as that using commercial ones. 

Substrate derivatization. This is undoubtedly the aspect of CMEs which has received most attention in the last ten years, and justifiably so. Without the development of convenient, reproducible preparation methods the study of CMEs will remain somewhat academic. Fortunately, it appears this is not to be the case, and feasible, practical electrode preparation methods appear regularly in the literature. As pointed out previously, the electrode should be easily and inexpensively prepared. It should also exhibit the desired chemical and physical properties, have an appropriate capacity and an adequate electron transfer rate constant for the analyte electrode process. 

Laves phase) alloys. Several battery alloy compositions are listed in table 2. Battery performance depends on the alloys, electrode preparation methods, and battery assembly. The performances of alloys are changed by various factors such as alloy composition, casting conditions, grain boundary phases, surface modification, etc. The important point is that the Ni-MH battery does not have a fixed performance, opening the possibility for remarkable progress in the future. 

HglHg2Cl2 electrode preparation. Method 1 [98]. Hg2Cl2 is added to dry mercury. After complete coverage of the surface with the salt, addition of Hg2Cl2 is stopped otherwise the electrode response will be slow. The HglHg2Cl2 interface must be prepared before introduction of filling solution. 

Silver electrodes prepared by any of the three methods are almost always subjected to a sintering operation prior to cell or battery assembly. 

Example. The Pechini method for fuel cell electrode preparation. La, Ba, Mn niU ates - - CgHgO — citrate complex - - C2FI6O2 — gel. Metal nitrates are complexed with citric acid, and then heated with ethylene glycol to form a transparent gel. This is then heated to 600 K to decompose the organic content and then to temperatures between 1000 and 1300K to produce tire oxide powder. The oxide materials prepared from the liquid metal-organic procedures usually have a more uniform particle size, and under the best circumstances, this can be less than one micron. Hence these particles are much more easily sintered at lower temperatures than for the powders produced by tire other methods. 

Electrode Surface preparation method Electrolyte vs. SHE (dEnJdcy (mV dm3 mol-1) fpz Atomic density/cm2 Method References... 

Using impedance data of TBN+ adsorption and back-integration,259,588 a more reliable value of <7 0 was found for a pc-Cu electrode574,576 (Table 11). Therefore, differences between the various EffM) values are caused by the different chemical states and surface structures of pc-Cu electrodes prepared by different methods (electrochemical or chemical polishing, mechanical cutting). Naumov etal,585 have observed these differences in the pzc of electroplated Cu films prepared in different ways. 

Many other opportunities exist due to the enormous flexibility of the preparative method, and the ability to incorporate many different species. Very recently, a great deal of work has been published concerning methods of producing these materials with specific physical forms, such as spheres, discs and fibres. Such possibilities will pave the way to new application areas such as molecular wires, where the silica fibre acts as an insulator, and the inside of the pore is filled with a metal or indeed a conducting polymer, such that nanoscale wires and electronic devices can be fabricated. Initial work on the production of highly porous electrodes has already been successfully carried out, and the extension to uni-directional bundles of wires will no doubt soon follow. 

The catalytic activity of an electrode is determined not only by the natnre of the electrode metal (its bulk properties) but also by the composition and stmcture of the snr-face on which the electrochemical reaction takes place. These parameters, in tnm, depend on factors such as the method of electrode preparation, the methods of snr-face pretreatment, conditions of storage, and others, all having little effect on the bulk properties. 

Fig. 5.18 Potentiostatic methods (A) single-pulse method, (B), (C) double-pulse methods (B for an electrocrystallization study and C for the study of products of electrolysis during the first pulse), (D) potential-sweep voltammetry, (E) triangular pulse voltammetry, (F) a series of pulses for electrode preparation, (G) cyclic voltammetry (the last pulse is recorded), (H) d.c. polarography (the electrode potential during the drop-time is considered constant this fact is expressed by the step function of time—actually the potential increases continuously), (I) a.c. polarography and (J) pulse polarography...

This is comparable to or slightly higher than the values reported for single crystal (11) and polycrystalline Ti02 (12), and much higher than those for the TiC>2 film electrode prepared by other methods such as chemical vapor deposition (13) and oxidation (14) and anodization (15) of Ti metal. The high efficiency of the dip-coated Ti(>2 film may be attributed to the porous nature of the film as described below. 

Electrochemical synthesis was utilized to prepare labeled compounds. Tetramethyllead labeled with 14C was prepared in a double compartment cell in DMF with NaClC>4, by electrolyzing 14CH3l on lead electrodes. The method is reported as superior to transmet-allation with methylmagnesium halide. It is also possible to incorporate lead isotopes. 2i°Pb2+ ions were deposited on a Cu foil and the latter was used as a sacrificial electrode in solutions of CH3I. The yield of labeled tetramethyllead was 85%65. Synthesis of 210Pb-labeled chlorotrimethylplumbane was also described66. 

The calibration curves for fructose were compared between PP/FDH/Pt and PP/FCN/FDH/Pt electrodes (prepared by the two-step method) [Fig.23]. In both cases, the response current was directly proportional to fructose concentration up to 10 mM and with a detection range of up to 30mM fructose. The minimum detection limit was 10 //M and 5 mM in the case of PP/FDH/Pt and PP/FCN/FDH/Pt electrodes, respectively. The slope of the linearity was about 80 nA/mM and 450 nA/mM, respectively. 

To implement this program of measurements on well-defined electrodes, the method of preparation of clean and well-ordered single crystal surfaces is essential. Such surfaces can be obtained either by the use of ultra-high vacuum or "atmospheric" procedures, the latter methods will briefly be described below. 

Electrochemistry offers new routes to the production of several commercially relevant a-arylpropionic acids, used as non-steroidal anti-inflammatory agents (NSAI) [178,182]. A preparative method based on sacrificial Al-electrodes has been set up for the electrocarboxylation of ketones [117,183-187] and successfully applied to the electrocarboxylation of aldehydes, which failed with conventional systems. The electrocarboxylation of 6-methoxy-acetonaphthone to 2-hydroxy-2-(6-methoxynaphthyl)propionic acid, followed by chemical hydrogenation to 2-(6-methoxynaphthyl)-2-propionic acid - one of the most active NSAI acids - has been developed up to the pilot stage [184,186],... 

More attention has been devoted to aromatic and heteroaromatic substrates since first reported in 1983 [40]. The results are shown in Table 2 [25, 41-51]. All these reactions were run with nickel complexes associated with a phosphane or bpy ligand. Depending on the experimental conditions, the polymers were either precipitated during the electrolysis or deposited as films at the surface of the electrode. The method is also convenient to prepare copolymers from a mixture of two aryl dihalides. A mechanistic investigation on the nickel-bpy catalyzed polymerisation has been reported very recently [52]. 

Microelectrodes were discussed briefly, including the methods of cleaning, and a procedure for making a simple microelectrode systems. Finally, electrodes prepared by screen-printing were mentioned. 

Q. Mao, G. Sun, S. Wang, et al. Gomparative studies of configurations and preparation methods for direct methanol fuel cell electrodes. Electrochimica Acta 52... 

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