Electrodes platinum

Walton D J, Phull S S, Chyla A, Lorimer J P, Mason T J, Burke L D, Murphy M, Compton R G, Ekiund J C and Page S D 1995 Sonovoltammetry at platinum electrodes surface phenomena and mass transport processes J. Appl. Electrochem. 25 1083... 

The overpotential required for the evolution of O2 from dilute solutions of HCIO4, platinum electrodes is approximately 0.5 V. 

The electrolytic processes for commercial production of hydrogen peroxide are based on (/) the oxidation of sulfuric acid or sulfates to peroxydisulfuric acid [13445-49-3] (peroxydisulfates) with the formation of hydrogen and (2) the double hydrolysis of the peroxydisulfuric acid (peroxydisulfates) to Caro s acid and then hydrogen peroxide. To avoid electrolysis of water, smooth platinum electrodes are used because of the high oxygen overvoltage. The overall reaction is... 

C. HIO is prepared by oxidation of iodine with perchloric acid, nitric acid, or hydrogen peroxide or oxidation of iodine in aqueous suspension to iodic acid by silver nitrate. Iodic acid is also formed by anodic oxidation at a platinum electrode of iodine dissolved in hydrochloric acid (113,114). 

Platiaum and its alloys are also used as biomedical electrodes, eg, platiaum—indium wires for permanent and temporary pacemaker leads and defibrillator leads. Electrophysiology catheters, which contain platinum electrodes and marker bands, have been used to map the electrical pathways of the heart so that appropriate treatment, such as a pacemaker, can be prescribed. 

Electrolytic reduction with a mercury or platinum electrode produces equimolar amounts of sulfide and sulfite ... 

A porous platinum electrode is used so that the oxygen can pass through the electrode and react with the gas sensor material. Oxygen ions move... 

It is stated that in time the acidity (up to 2,5 units) of 0,1-1,0 M HMTA aqueous solutions changes maximally at 1°C, in comparatively to other temperatures (11, 16, 21°C). When the temperature arises the change of HMTA aqueous solutions pH values decreases in time. Formaldehyde and ammonium ions (end products of HMTA hydrolysis) have been fixed only in more diluted solutions (0,10 and 0,25M). The concentration of NH in them in some times is higher than H2C=0 concentration that is caused by oxidation of the last one to a formic acid, being accompanied by the change of the system platinum electrode potential. It is stated that concentration NH in solutions does not exceed 5% from HMTA general content. The conclusion the mechanism of HMTA destruction in H,0 to depend essentially on its concentration and temperature has been made. 

Electrolysis of acidified water using platinum electrodes is a convenient source of hydrogen (and oxygen) and, on a larger scale, very pure hydrogen (>99.95%) can be obtained from the electrolysis of warm aqueous solutions of barium hydroxide between nickel electrodes. The method is expensive but becomes economical... 

Emission spectra have been recorded for four aryl-substituted isoindoles rmder conditions of electrochemical stimulation. Electrochemiluminescence, which was easily visible in daylight, was measured at a concentration of 2-10 mM of emitter in V jV-dimethylformamide with platinum electrodes. Emission spectra due to electrochemi-luminescence and to fluorescence were found to be identical, and quantum yields for fluorescence were obtained by irradiation with a calibrated Hght source. Values are given in Table X. As with peak potentials determined by cyclic voltammetry, the results of luminescence studies are interpreted in terms of radical ion intermediates. ... 

It is known that tropylium may be prepared from tropylidene via hydride abstraction by PhgC or MegC carbonium ions therefore, it is very likely that here too the dehydrogenation is a hydride transfer from the 1,5-dione to an acceptor. A similar dehydrogenation of chromanones to chromones, with triphenylmethyl perchlorate was reported. A study of the electrooxidation of 1,5-diones on a rotating platinum electrode showed that 1,5-diaryl-substituted diones afford pyrylium salts in these conditions and that the half-wave potentials correlate with yields in chemical dehydrogenations. 

Grove recognized that electrodes above the surface of an electrolyte, (e.g., sulfuric acid) would be wetted by capillary action and so allow the platinum electrodes to catalyze the electrochemical reactions of a fuel and oxidant stich as hydrogen and oxygen. 

Oxidation-reduction potential Because of the interest in bacterial corrosion under anaerobic conditions, the oxidation-reduction situation in the soil was suggested as an indication of expected corrosion rates. The work of Starkey and Wight , McVey , and others led to the development and testing of the so-called redox probe. The probe with platinum electrodes and copper sulphate reference cells has been described as difficult to clean. Hence, results are difficult to reproduce. At the present time this procedure does not seem adapted to use in field tests. Of more importance is the fact that the data obtained by the redox method simply indicate anaerobic situations in the soil. Such data would be effective in predicting anaerobic corrosion by sulphate-reducing bacteria, but would fail to give any information regarding other types of corrosion. 

The redox potential is determined with a probe consisting of a platinum electrode and a Hg/Hg2Cl2 Cl or Ag/Ag Cl—Cl reference electrode. If Ep is the potential of the platinum probe, Ej the potential of the reference electrode and tne redox potential of the soil (in mV on the hydrogen scale) then... 

Barnard, K. N., Christie, G. L. and Gage, D. G. Service Experience with Lead Silver Alloy Anodes in Cathodic Protection of Ships , Corrosion, 15, 11, 581-586 (1959) Peplow, D. B. and Shreir, L. L. Lead/Platinum Electrodes for Marine Applications , Corr. Tech. Apr. (1984)... 

Platinum has also had its share of attention in recent years. The effect of phosphoric acid concentration on the oxygen evolution reaction kinetics at a platinum electrode using 0-7 m-17-5 m phosphoric acid at 25°C has been studied with a rotating disc electrode . The characteristics of the ORR are very dependent on phosphoric acid concentration and H2O2 is formed as an intermediate reaction. Also, platinum dissolution in concentrated phosphoric acid at 176 and 196°C at potentials up to 0-9 (SHE) has been reported . 

Lead dioxide will readily form on lead with a platinum electrode as small as 0 076 mm in diameter" ". It has been observed that the current density on the platinum is considerably less than on the lead dioxide once polarisation has been achieved, the proportion of current discharged from the platinum decreasing with increase in total current. 

Fig. 19.16 Schematic E — I diagrams of local cell action on stainless steel in CUSO4 + H2SO4 solution showing the effect of metallic copper on corrosion rate. C and A are the open-circuit potentials of the local cathodic and anodic areas and / is the corrosion current. The electrode potentials of a platinised-platinum electrode and metallic copper immersed in the same solution as the stainless steel are indicated by arrows, (a) represents the corrosion of stainless steel in CUSO4 -I- H2 SO4, (b) the rate when copper is introduced into the acid, but is not in contact with the steel, and (c) the rate when copper is in contact with the stainless steel...

The cell notation is Zn Zn2+1 Co3+, Co2+ Pt Note that a comma separates the half-cell components that are in the same phase. The symbol Pt is used to indicate the presence of an inert platinum electrode. A single vertical line separates Pt (a solid) from the components of the half-cell, which are in the liquid phase. 

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