Palladium cathode

Kenneth and Steve Shoulders report an experiment in which a previously deuteron-loaded palladium cathode was subjected to the impact of a charge cluster [22]. Where the charge cluster impacted the deuteron-loaded palladium a visually-evident, explosive-like reaction occurs (Fig. 8). The palladium cathode was then subjected to an X-ray analysis of the impact crater (see chart in Fig. 8). Typically, the X-ray analysis shows a considerable number of elements not seen when scanning the nearby palladium surface. Such elements as oxygen, calcium, silicon, and magnesium are detected in the exploded region where a charge cluster impacted the palladium. 

The stereochemistry of cathodic hydrogenation is thus far not predictable or explainable. There is a preponderance for trans addition in the reduction of al-kynes, while cis addition occurs predominantly with cis- and trans-stilbene and maleic acid derivatives. On the other hand, dimethylmaleic acid and dimethyl-fumaric acid are exclusively hydrogenated to the trans products, meso- and dl-di-methylsuccinic acid 302 With a silver-palladium cathode in 5% aquous sulfuric acid triple bonds are reduced in a specific cis addition to double bonds 303 ... 

An illustration is the increased rate of the electrocatalytic reduction of 4-methylstyrene on deposition of small amounts of platinum or gold on a palladium cathode [121]. 

Finally a novel application of ultrasound in cold nuclear fusion has been published. This whole area remains controversial, but a Japanese patent claims that sonication of a cell in which D20 is electrolyzed at a palladium cathode causes an improvement in the efficiency of cold nuclear fusion [151]. Russian workers also report the generation of nuclear-fusion products during combined action of cavitation and electrolysis on the surface of titanium in deuterated electrolytes [151a], And there has been recent speculation regarding the capability of ultrasound to drive fusion effects within a cavitating bubble [151b],... 

The electrochemical cell used by Akamatsu et al. [36] to measure hydrogen permeability is shown in Fig. 8.10. A gas mixture of hydrogen and argon is introduced at the sample/ gas interface. Polarization measurements are performed in the potential range between —100 and 600 mV, so the palladium cathode is not oxidized. Hydrogen partial pressures range from 0.10 to 20.5 kPa. 

Bellanger G (2007), Enrichment of slightly concentrated tritiated water by electrolysis using a palladium cathode coated on ionic solid polymer membrane— Design and results. Fusion Eng Des, 82,395-405. 

Fleischmann, M. and Pons, S. (1992) Concerning the detection of neutrons and /-rays from cells containing palladium cathodes polarised in heavy water. Nuovo Cimento della Societa di FisicaA Nuclei, Particles and Fields, 105A, 763. 

Assuming that the palladium metal is a critical factor for the anomalous FPHE, it is not possible to make two palladium cathodes with exactly the same atomic airangements, impurity levels, etc. ThCTefore, two identical experiments cannot be carried out... 

MUes, M.H., Hollins, R.A., Bush, B.F. et al. (1993) Correlation of excess enthalpy and helium production during DjO and HjO electrolysis using palladium cathodes. Journal of Electroanalytical Chemistry, 346, 99-117. 

Packham, N.J.C., Wolf, K.L., Wass, J.C. etal. (1989) Production of tritium from DjO electrolysis at a palladium cathode. Journal of Electwanalytical Chemistry, 270, 451-458. 

Kunimatsu, K., Hasegawa, N., Kubota, A. et al. (1993) Deuterium loading ratio and excess heat generation during electrolysis of heavy water by a palladium cathode in a closed cell using a partially immersed fuel cell anode, in Frontiers of Cold Fusion (ed. H. Ikegami), Universal Academy Press, Tokyo, pp. 31-45. 

Recent experiments on the electrolysis of LiOD in D2O on a palladium cathode has been claimed to result in cold fusion. The detection of helium, neutrons, and even tritium has been reported. However, there is considerable doubt about the validity of the claims and cold fusion, like polywater will soon be buried and its obituary published. 

Poizot, P, L. Laffont-Dantras, J. Simonet. The one-electron cleavage and reductive homo-coupling of alkyl bromides at silver-palladium cathodes. J. Electroanal. Chem. 624, 2008 52-58. 

Cougnon, C. and J. Simonet. Are tetraalkylammonium cations inserted into palladium cathodes Formation of new palladium phases involving tetraalkylammonium... 

It has been claimed that the D-D fusion reaction occurs when D2O is electroly2ed with a metal cathode, preferably palladium, at ambient temperatures. This claim for a cold nuclear fusion reaction that evolves heat has created great interest, and has engendered a voluminous titerature filled with claims for and against. The proponents of cold fusion report the formation of tritium and neutrons by electrolysis of D2O, the expected stigmata of a nuclear reaction. Some workers have even claimed to observe cold fusion by electrolysis of ordinary water (see, for example. Ref. 91). The claim has also been made for the formation of tritium by electrolysis of water (92). On the other hand, there are many experimental results that cast serious doubts on the reahty of cold fusion (93—96). Theoretical calculations indicate that cold fusions of D may indeed occur, but at the vanishingly small rate of 10 events per second (97). As of this writing the cold fusion controversy has not been entirely resolved. 

Cold fusion has been reported to result from electrolyzing heavy water using palladium [7440-05-3] Pd, cathodes (59,60). Experimental verification of the significant excess heat output and various nuclear products are stiU under active investigation (61,62) (see Eusion energy). 

Multiphase gold or palladium-based alloys never show dissolution of Au or Pd but often exhibit progressive surface ennoblement due to selective dissolution of copper or silver from the outer 2-3 atomic layers Heat treatment often decomposes multicomponent alloys into a Pd-Cu rich compound and an Ag-rich matrix with corrosion of the latter phase in deaerated artificial saliva and S -containing media . Au-Cu-rich lamellae have similarly been observed, again with preferential attack on Ag-rich phases or matrix. These effects presumably arise from the ability of the noble alloy phases to catalyse the cathodic reduction of oxygen . 

In March 1989, Martin Fleischmann and Stanley Pons reported their discovery of cold nuclear fusion. They announced that during electrolysis of a solution of hthium hydroxide in heavy water (DjO) with a cathode made of massive palladium, nuclear transformations of deuterium at room temperature can be recorded. This announcement, which promised humankind a new and readily available energy source, was seized upon immediately by the mass media in many countries. Over the following years, research was undertaken worldwide on an unprecedented scale in an effort to verify this finding. 

Since the reaction between hydrogen and oxygen is very slow at room temperature, catalysts are incorporated in the carbon electrodes. At the anode, suitable catalysts are finely divided into platinum or palladium at the cathode, cobaltous oxide, or silver. The two halfreactions shown above yield the overall result as ... 

The stereochemistry of electrochemical reduction of acetylenes is highly dependent upon the experimental conditions under which the electrolysis is carried out. Campbell and Young found many years ago that reduction of acetylenes in alcoholic sulfuric acid at a spongy nickel cathode produces cis-olefins in good yields 126>. It is very likely that this reduction involves a mechanism akin to catalytic hydrogenation, since the reduction does not take place at all at cathode substances, such as mercury, which are known to be poor hydrogenation catalysts. The reduction also probably involves the adsorbed acetylene as an intermediate, since olefins are not reduced at all under these conditions and since hydrogen evolution does not occur at the cathode until reduction of the acetylene is complete. Acetylenes may also be reduced to cis olefins in acidic media at a silver-palladium alloy cathode, 27>. 

To date, a few methods have been proposed for direct determination of trace iodide in seawater. The first involved the use of neutron activation analysis (NAA) [86], where iodide in seawater was concentrated by strongly basic anion-exchange column, eluted by sodium nitrate, and precipitated as palladium iodide. The second involved the use of automated electrochemical procedures [90] iodide was electrochemically oxidised to iodine and was concentrated on a carbon wool electrode. After removal of interference ions, the iodine was eluted with ascorbic acid and was determined by a polished Ag3SI electrode. The third method involved the use of cathodic stripping square wave voltammetry [92] (See Sect. 2.16.3). Iodine reacts with mercury in a one-electron process, and the sensitivity is increased remarkably by the addition of Triton X. The three methods have detection limits of 0.7 (250 ml seawater), 0.1 (50 ml), and 0.02 pg/l (10 ml), respectively, and could be applied to almost all the samples. However, NAA is not generally employed. The second electrochemical method uses an automated system but is a special apparatus just for determination of iodide. The first and third methods are time-consuming. 

The reduction is usually made in a multi-compartment electrochemical cell, where the reference electrode is isolated from the reaction solution. The solvent can be water, alcohol or their mixture. As organic solvent A,A-dimethyl form amide or acetonitrile is used. Mercury is often used as a cathode, but graphite or low hydrogen overpotential electrically conducting catalysts (e.g. Raney nickel, platinum and palladium black on carbon rod, and Devarda copper) are also applicable. 

The cells shown in Figs. 28 and 29 all operate according to the same principles, which have been developed by Arup. The interior of the cell acts as the anode chamber, and a metal oxide cathode placed inside the cell in an alkaline electrolyte acts as the counter electrode. The hydrogen flux across the integrated membrane (coated with palladium on the internal surface) can be measured as the potential drop across a resistor placed between the membrane and the counter electrode. 

Cathode Platinum metals, especially platinum and palladium, achieve the lowest known overvoltages for hydrogen. Moreover, they are effective catalysts for hydrogenation reactions [15]. 

Organic electroreductive coupling reactions using transition-metal complexes as catalysts have been widely investigated. Reviews on the subject have been published [89, 90]. The method involving the most common transition-metal complexes (nickel, cobalt, palladium) appears to be a useful tool to synthetize heterocycles from organic halides via radical intermediates. Nickel catalyst precursors are nickel(II) salts that are cathodically reduced either to nickel(I) or to nickel(O) and cobalt catalyst... 

Scheme 69 Palladium(0) catalyzed cathodic cydization of aryl bromides and double bonds.

Reduction of nonconjugated aromatic ketones gave at metal cathodes (e.g., tin, copper, silver, palladium, zinc) the cis isomers (ds-H/OH) of cycKzed products in high diastereoselectivity. The electroreduction of 5-phenylpentan-2-one led to 70% of an exclusively ds-hexahydronaphthalene... 

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