Bronze electrodes

MS—solid bronze electrodes made from drillings. Tin content from slurry technique (above) used for internal standard. Rel. sensitivity factors obtained from NBS standards C1115, C1116, C1117, 124, and CA4. 

K. Machido and M. Enyo, Tungsten bronze electrodes doped with platinum (methanol oxidation), J. Electrochem. Soc. 135 1955 (1988). 

Sil-Trode [Ampco]. TM for silicon bronze electrodes and filler rod for use in inert-gas welding. 

Similar, but cyclic mechanism with hydrogen bronze formation is given for rare earth platinum bronze electrodes [11]. It is known that Ru adsorbs OH species better than platinum [12] and hence presence of Ru in near vicinity of Pt enhances the oxidation of half combusted or partially oxidised poisons adsorbed on Pt as shown below... 

The conductivity measurements were made by a.c. methods (silver paint electrodes) and by d.c. methods (hydrogen molybdenum bronze electrodes). The measurements were made in the temperature range from —10 °C to 85 °C. In the lower part of the temperature range, the Arrhenius plots show linear behaviour. In the upper part (30-85 °C), the Arrhenius law was not obeyed. 

Mchardy J, Bockris JO (1973) Electrocatalysis of oxygen reduction by sodium tungsten bronze I. Surface characteristics of a bronze electrode. J Electrochem Soc 120(l) 53-60... 

Machida K, Enyo M, Adachi G, Shiokawa J. Methanol oxidation characteristics of rare earth tungsten bronze electrodes doped with platinum. J Electrochem Soc 1988 135 1955-61. 

EIS characterization of laprol 2402C adsorption on copper, tin and bronze electrodes. Chemistry (Vilnius), 12 (3), 210-215,... 

M. Jitaru and M. Toma, Electroreduction of carbon dioxide to formate on bronze electrodes, Studia Univ. Babes-Bolyai. Chemia 53,2008,135-142. 

Figure 1. Specific charge (thick line) and discharge (thin line) capacity of tin electrode without annealing. Bronze interface is absent. Current collector - copper. Testing mode C/5. Counter electrode - lithium foil. Separators - 2 layers of unwoven polypropylene (Mogilev, Belarus).

J. Gabel, W. Vonau, P. Shuk, and U. Guth, New reference electrodes based on tungsten-substituted molybdenum bronzes. Solid State Ionics 169, 75-80 (2004). 

In electrostatic atomization, an electrical potential is applied between a liquid to be atomized and an electrode placed in the spray at a certain distance from liquid discharge nozzle. As a result of the mutual repulsion of like charges accumulated on the liquid surface, the surface becomes unstable and disrupts when the pressure due to the electrostatic forces exceeds the surface tension forces of the liquid. Droplets will be generated continuously if the electrical potential is maintained above a critical value consistent with liquid flow rate. Both DC and AC systems have been employed to provide high electrical potentials for generating fine droplets. Many configurations of electrode have been developed, such as hypodermic needles, sintered bronze filters, and cones. 

At IREQ, besides the participation in the field tests run by the engineers of Hydro-Quebec (12), the main effort has been to tackle fundamental problems in the field of electrocatalysis (18-22) and of anodic oxidation of different potential fuels (23-26). A careful and extensive study of the electrochemical properties of the tungsten bronze has been carried out (18-20) the reported activity of these materials in acid media for the oxygen reduction could not be reproduced and this claim by other workers has been traced back to some platinum impurities in the electrodes. Some novel techniques in the area of electrode preparation are also under study (21,22) the metallic deposition of certain metals on oriented graphite show some interesting catalytic features for the oxygen reduction and also for the oxygen evolution reaction. 

Researchers are looking at ways to reduce the amount of platinum yet retain the catalytic activity. Peter Strasser, a researcher at the University of Houston in Texas, and his colleagues are trying to develop a platinum alloy that will do the job. An alloy such as bronze is a combination of elements, which in the case of bronze are tin and copper. Engineers often use alloys because they offer properties that are superior to those of a single metal, as described in chapter 1. A platinum alloy that acts as an effective catalyst in fuel cell electrodes yet contains less platinum would save a substantial amount of money. 

An example of the application of Tafel analysis is provided by samples taken for a bronze montefortino helmet from the Gabriel river valley (Kelin and Ikalesken period) in the Valencian region of Requena, dated back to the Second Iron Age (see Fig. 3.13). Upon attachment to paraffin-impregnated graphite electrodes immersed in 0.50 M phosphate buffer, voltammetric signals such as depicted in Fig. 3.14 were found [183]. 

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