Carbon monoxide electrode

Two different reference electrodes are commonly used for electrochemical measurements in molten carbonates the oxygen electrode and the carbon monoxide electrode. 

Karpachov SV, Filiayev AT, Palguyev SF (1964) Polarization of carbon monoxide electrodes on platinum in a solid zirconia-lime electrolyte. Electrochim Acta 9 1681-1685... 

Further down, ca 75 cm below the electrode tips, the mix is hot enough (2200—2500°C) to allow the lime to melt. The coke does not melt and the hquid lime percolates downward through the relatively fixed bed of coke forming calcium carbide, which is Hquid at this temperature. Both Hquids erode coke particles as they flow downward. The weak carbide first formed is converted to richer material by continued contact and reaction with coke particles. The carbon monoxide gas produced in this area must be released by flowing back up through the charge. The process continues down to the taphole level. Material in this area consists of soHd coke wetted in a pool of Hquid lime and Hquid calcium carbide at the furnace bottom. 

The reduction of carbon dioxide is another of the basic electrochemical reactions that has been studied at modified electrodes. The reduction at Co or Ni phthalocyanine in acidic solution yields formic acid or carbon monoxide A very high selectiv-... 

Ruthenium is a known active catalyst for the hydrogenation of carbon monoxide to hydrocarbons (the Fischer-Tropsch synthesis). It was shown that on rathenized electrodes, methane can form in the electroreduction of carbon dioxide as weU. At temperatures of 45 to 80°C in acidihed solutions of Na2S04 (pH 3 to 4), faradaic yields for methane formation up to 40% were reported. On a molybdenium electrode in a similar solution, a yield of 50% for methanol formation was observed, but the yield dropped sharply during electrolysis, due to progressive poisoning of the electrode. 

On the surface of metal electrodes, one also hnds almost always some kind or other of adsorbed oxygen or phase oxide layer produced by interaction with the surrounding air (air-oxidized electrodes). The adsorption of foreign matter on an electrode surface as a rule leads to a lower catalytic activity. In some cases this effect may be very pronounced. For instance, the adsorption of mercury ions, arsenic compounds, or carbon monoxide on platinum electrodes leads to a strong decrease (and sometimes total suppression) of their catalytic activity toward many reactions. These substances then are spoken of as catalyst poisons. The reasons for retardation of a reaction by such poisons most often reside in an adsorptive displacement of the reaction components from the electrode surface by adsorption of the foreign species. 

The Pt-Rn catalysts have another important property. In contrast to pure platinum, they are almost insensitive to poisoning by carbon monoxide CO. They can be used, therefore, in the hydrogen electrodes of hydrogen-oxygen fuel cells operated with technical hydrogen containing marked amonnts of CO. 

PEMFC)/direct methanol fuel cell (DMFC) cathode limit the available sites for reduction of molecular oxygen. Alternatively, at the anode of a PEMFC or DMFC, the oxidation of water is necessary to produce hydroxyl or oxygen species that participate in oxidation of strongly bound carbon monoxide species. Taylor and co-workers [Taylor et ah, 2007b] have recently reported on a systematic study that examined the potential dependence of water redox reactions over a series of different metal electrode surfaces. For comparison purposes, we will start with a brief discussion of electronic structure studies of water activity with consideration of UHV model systems. 

Mechanisms of the Oxidation of Carbon Monoxide and Small Organic Molecules at Metal Electrodes... 

In this chapter, we have summarized (recent) progress in the mechanistic understanding of the oxidation of carbon monoxide, formic acid, methanol, and ethanol on transition metal (primarily Pt) electrodes. We have emphasized the surface science approach employing well-defined electrode surfaces, i.e., single crystals, in combination with surface-sensitive techniques (FTIR and online OEMS), kinetic modeling and first-principles DFT calculations. 

Beltramo G, Shubina TE, Koper MTM. 2005. Oxidation of formic acid and carbon monoxide on gold electrodes studied by surface-enhanced Raman spectroscopy and DFT. ChemPhysChem 6 2597-2606. 

Garcia G, Koper MTM. 2008. Stripping voltammetry of carbon monoxide oxidation on stepped platinum single-crystal electrodes in alkaline solution. Phys Chem Chem Phys 10 3802-3811. 

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Lai SCS, LehedevaNP, Housmans THM, Koper MTM. 2007. Mechanisms of carbon monoxide and methanol oxidation at single-crystal electrodes. Top Catalysis 46 320-333. 

Love B, Lipkowski J. 1988. Effect of surface crystallography on electrocatalytic oxidation of carbon monoxide on Pt electrodes. ACS Symp Ser 378 484. 

McCallum C, Pletcher D, 1978. An investigation of the mechanism of the oxidation of carbon monoxide adsorbed onto a smooth Pt electrode in aqueous acid. J Electroanal Chem 70 277. 

Roberts JL, Sawyer DT. 1964. Voltammetric determination of carbon monoxide at gold electrodes. J Electroanal Chem 7 315-319. 

Lin W-F, Sun S-G, Tian Z-W. 1994. Investigations of coadsorption of carbon monoxide with S or Bi adatoms at a platinum electrode by in-situ FTIR spectrocopy and quantum chemistry analysis. J Electroanal Chem 364 1-7. 

Watanabe M, Shibata M, Motoo S. 1985. Electrocatalysis hy ad-atoms. PartXn. Enhancement of carbon monoxide oxidation on platinum electrodes by oxygen adsorbing ad-atoms (Ge, Sn, Pb, As, Sb and Bi). J Electroanal Chem 187 161-174. 

Brankovic SR, Marinkovic NS, Wang JX, Adzic RR. 2002b. Carbon monoxide oxidation on bare and Pt-modified Ru(lOlO) and Ru(OOOl) single crystal electrodes. J Electroanal Chem 532 57-66. 

Kabbabi A, Faure R, Durand R, Beden B, Hahn F, Leger JM, Lamy C. 1998. In situ FTIRS study of the electrocatalytic oxidation of carbon monoxide and methanol at platinum-ruthenium bulk alloy electrodes. J Electroanal Chem 444 41-53. 

Akemann W, Friedrich KA, Linke U, Stimming U. 1998. The catal)4ic oxidation of carbon monoxide at the platinum/electrolyte interface investigated by optical second harmonic generation (SHG) Comparison of Pt(l 11) and Pt(997) electrode surfaces. Surf Sci 404 571-575. 

Chou KC, Kim J, Baldelli S, Somorjai GA. 2003a. Vibrational spectroscopy of carbon monoxide, acetonitrile, and phenylalanine adsorbed on liquid vertical bar electrode interfaces by sum frequency generation. J Electroanal Chem 554 253-263. 

KitamuraF, Takahashi M, Ito M. 1989. Carbon monoxide adsorption on platinum (111) singlecrystal electrode surface studied by infrared reflection - absorption spectroscoy. Surf Sci 223 493-508. 

Korzeniewski C, Pons S, Schmidt PP, Severson MW. 1986. A theoretical analysis of the vibrational spectrum of carbon monoxide on platinum metal electrodes. J Chem Phys 85 4153-4160. 

Kunimatsu K, Golden WG, Seki H, Philpott MR. 1985a. Carbon monoxide adsorption on a platinum electrode studied by polarization modulated FT-IRRAS. 1. Co Adsorbed in the double-layer potential region and its oxidation in acids. Langmuir 1 245 -250. 

Leung L-WH, Wieckowski A, Weaver MJ. 1988. In situ infrared spectroscopy of well-defined single-crystal electrodes Adsorption and electrooxidation of carbon monoxide on plati-nuk(lll). J Phys Chem 92 6985-6990. 

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