Hydrogen electrochemistry

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. 

Hosier H, Richter B, Behm RJ. 2004. Catalytic influence of Pt monolayer islands on the hydrogen electrochemistry of Ru(OOOl) studied by ultrahigh vacuum scanning tunneling microscopy and cychc voltammetry. J Phys Chem B 108 14780. 

Bai L, Harrington DA, Conway BE. Behavior of overpotential-deposited species in Faradaic reactions-II. AC Impedance measurements on H2 evolution kinetics at activated and unactivated Pt eathodes. Electrochim Acta 1987 32(12) 1713-31. Markovic NM, Grgur BN, Ross PN. Temperature-dependent hydrogen electrochemistry on platinum low-index single-crystal surfaces in acid solutions. J PhysChemB 1997 101(27) 5405-13. 

Markovica, N.M., Sarraf, S.T., Gasteiger, HA., and Ross, P.N. (1996) Hydrogen electrochemistry on platinum low-index single-crystal surfltces in alkaline solution. Journal of the Chemical Society, Faraday Transactions, 92, 3719-3725. 

Other Coordination Complexes. Because carbonate and bicarbonate are commonly found under environmental conditions in water, and because carbonate complexes Pu readily in most oxidation states, Pu carbonato complexes have been studied extensively. The reduction potentials vs the standard hydrogen electrode of Pu(VI)/(V) shifts from 0.916 to 0.33 V and the Pu(IV)/(III) potential shifts from 1.48 to -0.50 V in 1 Tf carbonate. These shifts indicate strong carbonate complexation. Electrochemistry, reaction kinetics, and spectroscopy of plutonium carbonates in solution have been reviewed (113). The solubiUty of Pu(IV) in aqueous carbonate solutions has been measured, and the stabiUty constants of hydroxycarbonato complexes have been calculated (Fig. 6b) (90). 

Acetonitrile and hydrogen cyanide are hy-products that may he recovered for sale. Acetonitrile (CH3CN) is a high polarity aprotic solvent used in DNA synthesizers, high performance liquid chromatography (HPLC), and electrochemistry. It is an important solvent for extracting butadiene from C4 streams. Table 8-1 shows the specifications of acrylonitrile, HCN, and acetonitrile. ... 

However, when the second stage in the hydrogen evolution reaction is electrochemical desorption, the rate of this reaction is increased as the potential falls, and the adsorbed hydrogen concentration may remain constant or fall, according to the detailed electrochemistry. This results in curves such as that shown in Fig. 8.38 for steel in sodium chloride solution. 

The present Section, which provides an outline of selected relevant topics in electrochemistry, is intended primarily as an introduction to aqueous corrosion for those readers whose basic training has not involved a study of electrochemistry. The scope of electrochemistry is enormous and cannot be treated adequately here, but there are now a number of excellent books on the subject, and it is hoped that this outline will serve to stimulate further study. The topics selected are as follows a) the nature of the electrified interface between the metal and the solution, (b) adsorption, (c) transfer of charge across the interface under equilibrium and non-equilibrium conditions, d) overpotential and the rate of an electrode reaction and (e) the hydrogen evolution reaction and hydrogen absorption by ferrous alloys. For reasons of space a number of important topics, such as the electrochemistry of electrolyte solutions, have been omitted. 

The concentration of the solution within the glass bulb is fixed, and hence on the inner side of the bulb an equilibrium condition leading to a constant potential is established. On the outside of the bulb, the potential developed will be dependent upon the hydrogen ion concentration of the solution in which the bulb is immersed. Within the layer of dry glass which exists between the inner and outer hydrated layers, the conductivity is due to the interstitial migration of sodium ions within the silicate lattice. For a detailed account of the theory of the glass electrode a textbook of electrochemistry should be consulted. 

In contrast, sulphoxides appear to possess a more classical behaviour in electrochemistry, due to their intermediate oxidation state which allows, in most of the cases, their reduction to sulphides but also their oxidation to sulphones with no cleavage process. Moreover, the increase of the sulphur atom basicity may also produce catalytic hydrogen evolution in acidic solution. 

Figure 7.12 shows the relationship between the standard oxygen electrode (soe) scale of solid state electrochemistry, the corresponding standard hydrogen electrode (she) scale of solid state electrochemistry, the standard hydrogen electrode (she) scale of aqueous electrochemistry, and the physical absolute electrode scale. The first two scales refer to a standard temperature of 673.15 K, the third to 298.15 K. In constructing Figure 7.12 we have used the she aqueous electrochemical scale as presented by Trasatti.14... 

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. 

Aprotic polar solvents such as those listed in Table 8.1 are widely used in electrochemistry. In solutions with such solvents the alkali metals are stable and will not dissolve under hydrogen evolution (by discharge of the proton donors) as they do in water or other protic solvents. These solvents hnd use in new types of electrochemical power sources (batteries), with hthium electrodes having high energy density. 

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