Platinum electrodes early developments

Electrochemical-deposition Electrode. Vilambi-Reddy et al. [62] presented the early research on the electrochemical deposition electrode. They developed an electrochemical catalyzation (ECC) technique to deposit platinum catalyst particles selectively in the regions accessible to both ions and electrons. In the ECC technique, a hydrophobic porous carbon paper was first coated with dispersed carbon particles and PTFE to form a substrate. Then the Nafion ionomer was impregnated onto this carbon substrate. This substrate was then placed into a platinum acid-plating bath, along with a platinum counter electrode. One side of this substrate, without Nafion, was masked with a non-conducting film, which... 

One energy application of methanol in its early stages of development is the direct methanol fuel cell (DMFC). A fuel cell is essentially a battery in which the chemicals are continuously supplied from an external source. A common fuel cell consists of a polymer electrolyte sandwiched between a cathode and anode. The electrodes are porous carbon rods with platinum... 

The electrodes are manufactured and distributed by MEDTRONIC (Minneapolis, USA). The epidural implantation is performed under local anesthesia. The second electrode type consists of four platinum disks that are embedded in a silicone rubber carrier. They have a diameter up to 6 mm (Fig. 7). They are implanted close to the spinal cord under complete ane sthesia. Surgical procedures have been developed from the early 1970s up to the present [43]. Current designs offer the possibility of externally correcting small dislocation of electrodes [44]. Meanwhile more than 300 patients have benefitted from this therapy. 

The electrochemical reaction proceeds most effectively in the presence of a catalyst, and the nature of the catalyst can have a significant effect upon the electrode overpotentials. As a matter of convenience, all of the early work in the electrolyzer development used platinum as both the anode (SO2 oxidation electrode) and cathode (H2 generation electrode) catalyst. It was recognized, however, that although platinum might be a technically satisfactory catalyst for the cathode, it was only marginally suitable as the anodic catalyst. 

Although one of the more complex electrochemical techniques [1], cyclic voltammetry is very frequently used because it offers a wealth of experimental information and insights into both the kinetic and thermodynamic details of many chemical systems [2], Excellent review articles [3] and textbooks partially [4] or entirely [2, 5] dedicated to the fundamental aspects and apphcations of cyclic voltammetry have appeared. Because of significant advances in the theoretical understanding of the technique today, even complex chemical systems such as electrodes modified with film or particulate deposits may be studied quantitatively by cyclic voltammetry. In early electrochemical work, measurements were usually undertaken under equilibrium conditions (potentiometry) [6] where extremely accurate measurements of thermodynamic properties are possible. However, it was soon realised that the time dependence of signals can provide useful kinetic data [7]. Many early voltammet-ric studies were conducted on solid electrodes made from metals such as gold or platinum. However, the complexity of the chemical processes at the interface between solid metals and aqueous electrolytes inhibited the rapid development of novel transient methods. 

Carbon corrosion and platinum dissolution in the acidic electrolyte at elevated temperatures are well recognized from the early years of research on PAFCs and are definitely relevant to HT-PEMFCs based on the acid-doped FBI membranes. Both mechanisms are enhanced at higher temperatures and higher electrode potentials. This should be taken into account when platinum alloy catalysts are considered for the HT-PEMFC. More efforts are also needed to develop resistant support materials based on either structured carbons or non-carbon alternatives. 

As early as the 1950s, the Austrian battery specialist Karl Kordesch built a rather efficient zinc-air battery with a new type of carbon-air electrode (Kordesch and Marko, 1951). In later work at the U.S. company Union Carbide, Kordesch developed a fuel cell with an alkaline electrolyte using multilayer carbon electrodes with a small amount of platinum on the hydrogen side and with cobalt oxide on the oxygen side. He put a battery of such fuel cells into his car and was the first person to regularly use an electric car with fuel cells on city roads in Cleveland and Parma, Ohio (Kordesch, 1963). 

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