Platinum, electrochemistry

In this case, the situation is very different since a complete reduction of the metal occurs with the formation of low-coordinated metallic atoms projected toward the outer layer of the interface. The model of conventional platinum electrochemistry suggests that there are two limiting types of surface metal atoms involved, which display significantly different actions. The overall reaction scheme may be presented as follows [94] ... 

IV. SINGLE CRYSTALS AND OLD PLATINUM ELECTROCHEMISTRY TRY TO MEET HALF-WAY... 

Differential values of Y can be also useful for interpretation of electrosorption valency in terms of sulfate vesus bi-suUate adsorption, as one of mostly untapped resources of platinum electrochemistry. However the main progress is expected from combination of precise electrochemistry, thermodynamic analysis, and independent physical information supported by an appropriate theoretical basis, with necessary links provided by computational community. The final Section contains some brief notes in this respect. 

This brief review is limited to consideration of platinum group metals in aqueous solutions. Thermodynamic approaches should work in other protic solvents. However these solvents are always of organic nature, and the experimental measurements of any thermodynamic quantities are complicated by irreversible dissociative adsorption of organic species. Another interesting field, still separated, is platinum electrochemistry in aptotic media. 

The limited anodic potential range of mercury electrodes has precluded their utility for monitoring oxidizable compounds. Accordingly, solid electrodes with extended anodic potential windows have attracted considerable analytical interest. Of the many different solid materials that can be used as working electrodes, the most often used are carbon, platinum, and gold. Silver, nickel, and copper can also be used for specific applications. A monograph by Adams (17) is highly recommended for a detailed description of solid-electrode electrochemistry. 

The first reported electroorganic synthesis of a sizeable amount of material at a modified electrode, in 1982, was the reduction of 1,2-dihaloalkanes at p-nitrostyrene coated platinum electrodes to give alkenes. The preparation of stilbene was conducted on a 20 pmol scale with reported turnover numbers approaching 1 x 10. The idea of mediated electrochemistry has more frequently been pursued for inorganic electrode reactions, notably the reduction of oxygen which is of eminent importance for fuel cell cathodes Almost 20 contributions on oxygen reduction at modified... 

The combination of hydrogen gas, H3 O ions, and a platinum electrode is referred to as a hydrogen electrode. This electrode appears in the right-hand portion of Figure 19-8. When a hydrogen electrode operates under standard conditions, PH2 — 1-00 bar and H3 O ] — 1.00 M, it is a standard hydrogen electrode (SHE). The standard hydrogen electrode is particularly important in electrochemistry, as we describe in Section 19-1. 

Although the Initial use of glassy carbon as an electrode material Indicated that It might be a viable substitute for platinum (1), subsequent Investigations have shown that glassy carbon Is quite complex as an electrode material. The conditions used to manufacture a particular sample of glassy carbon and the subsequent steps used to treat the surface for electrochemistry strongly Influence Its behavior, possibly even more so than with platinum. 

Cyclic voltammetry is perhaps the most important and widely used technique within the field of analytical electrochemistry. With a theoretical standard hydrogen electrode at hand, one of the first interesting and challenging applications may be to try to use it to make theoretical cyclic voltammograms (CVs). In following, we set out to do this by attempting to calculate the CV for hydrogen adsorption on two different facets of platinum the (111) and the (100) facets. 

Markovic NM, Grgur BN, Ross PN. 1997. Temperature-dependent hydrogen electrochemistry on platinum low-index single-crystal surfaces in acid solutions. J Phys Chem B 101 5405-5413. 

Henero E, Franaszczuk K, Wieckowski A. 1994. Electrochemistry of methanol at low index crystal planes of platinum An integrated voltammetric and chronoamperometric study. J Phys Chem 98 5074-5083. 

Climent V, Gomez R, Orts JM, Aldaz A, Eehu JM. 2000. Potential of zero total charge of platinum single crystal electrodes. In Jerkiewicz G, Eehu JM, Popov BN, eds. The Electrochemistry Society Proceedings (Hydrogen at Surface and Interfaces). Pennington, NJ The Electrochemical Society, pp. 12-30. 

Mitsushima S, Koizumi Y, Ota K, Kamiya N. 2007b. Solubility of platinum in acidic media (1)—In sulfuric acid. Electrochemistry 75 155-158. 

Durand R, Faure R, Gloaguen F, Aherdam D. 1996. Oxygen reduction reaction on platinum in acidic medium From bulk material to nanoparticles. In Adzic RR, Anson EC, Kinoshita K. editors. Proceedings of the Symposium on Oxygen Electrochemistry. Pennington, NJ The Electrochemical Society. 

A review9 with more than 37 references includes an examination of symmetry groups and chirality conditions for C60 and C70 bonded to one or two metals in rf and/or rf fashion. Palladium and platinum rf complexes of C6o and C70 are described (novel synthesis, NMR spectra, electrochemistry) as well as first optically active organometallic fullerene derivatives. 

The synthesis, X-ray structure, NMR, and UV-visible spectroscopy, and electrochemistry of a macrocyclic platinum(II) complex containing the tetradentate 1,4,7,10-tetrathiacyclodecane ligand, [12]aneS4 (144) have been reported.350 Related complexes including [Pt([13]aneS4)]2+ and [Pt([16]aneS4)]2+ have also been prepared, and molecular mechanics calculations complemented... 

Zinc dithiocarbamates have been used for many years as antioxidants/antiabrasives in motor oils and as vulcanization accelerators in rubber. The crystal structure of bis[A, A-di- -propyldithio-carbamato]zinc shows identical coordination of the two zinc atoms by five sulfur donors in a trigonal-bipyramidal environment with a zinc-zinc distance of 3.786 A.5 5 The electrochemistry of a range of dialkylthiocarbamate zinc complexes was studied at platinum and mercury electrodes. An exchange reaction was observed with mercury of the electrode.556 Different structural types have been identified by variation of the nitrogen donor in the pyridine and N,N,N, N -tetra-methylenediamine adducts of bis[7V,7V-di- .vo-propyldithiocarbamato]zinc. The pyridine shows a 1 1 complex and the TMEDA gives an unusual bridging coordination mode.557 The anionic complexes of zinc tris( V, V-dialkyldithiocarbamates) can be synthesized and have been spectroscopically characterized.558... 

Figure 2.1 (a) A schematic representation of the apparatus employed in an electrocapillarity experiment, (b) A schematic representation of the mercury /electrolyte interface in an electro-capillarity experiment. The height of the mercury column, of mass m and density p. is h, the radius of the capillary is r, and the contact angle between the mercury and the capillary wall is 0. (c) A simplified schematic representation of the potential distribution across the metal/ electrolyte interface and across the platinum/electrolyte interface of an NHE reference electrode, (d) A plot of the surface tension of a mercury drop electrode in contact with I M HCI as a function of potential. The surface charge density, pM, on the mercury at any potential can be obtained as the slope of the curve at that potential. After Modern Electrochemistry, J O M. 

In 1986, Breikss and Abruna reported electrochemical and mechanistic studies on a close analogue of the rhenium complex, (Dmbpy)Re[CO]3Cl, where Dmbpy = 4,4 dimethyl 2,2 bipyridine. The cyclic voltammogram of the complex at platinum in CH3CN/tetrabutylammonium perchlorate is shown in Figure 3.56 for simplicity we will consider only the electrochemistry taking place above c. —2.3V vs. SCE. 

D.T. Sawyer and J.L. Roberts, Electrochemistry of oxygen and superoxide ion in dimethyl sulfoxide at platinum, gold, and mercury electrodes. J. Electroanal. Chem. 12, 90-101 (1966). 

The electrochemistry of Ti2+ in 66.7 m/o AlCl3-NaCl has been investigated wherein the electroactive Ti2+ was prepared by the oxidation of Ti metal with liquid A1C13 [176, 185] and by the electrochemical dissolution of titanium metal [120, 177], The authors of both studies concluded that Ti2+ may be oxidized stepwise to Ti3+ and Ti4+ and that both processes are reversible at platinum and tungsten electrodes. However, anomalous voltammetric behavior at high Ti2+ concentrations (greater than 50 mmol L ) suggests the formation of polymeric Ti2+ species in the melt. The reduction of Ti2+ to the metal was not observed at potentials more positive than that required for aluminum deposition. 

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