Bockris isotherm

Habib, and surface potential determination, 893 Habib llockris model of water, 899 I Iabib Bockris isotherm, 943,949 Half-crystal position, electrodeposition,... 

I.H.P. and O.H.P. (the diffuse layer being disregarded), and adistinction is made between contact-adsorbed ions and ions electrostatically adsorbed by long-range coulombk forces, Wroblowa, Kovac and Bockris showed that when = 0(pzc). the B,D.M. isotherm can be expressed in the form... 

At Pt electrodes, adsorption of oxygen species is supposed to be controlled by the Temkin isotherm in the low overpotential region [Damjanovic and Bockris, 1966], whereas in the higher overpotential region, the absence of an oxide layer leads to... 

Most earlier papers dealt with the mercury electrode because of its unique and convenient features, such as surface cleanness, smoothness, isotropic surface properties, and wide range of ideal polarizability. These properties are gener y uncharacteristic of solid metal electrodes, so the results of the sohd met electrolyte interface studies are not as explicit as they are for mercury and are often more controversial. This has been shown by Bockris and Jeng, who studied adsorption of 19 different organic compounds on polycrystaUine platinum electrodes in 0.0 IM HCl solution using a radiotracer method, eUipsometry, and Fourier Transform Infrared Spectroscopy. The authors have determined and discussed adsorption isotherms and the kinetics of adsorption of the studied compounds. Their results were later critically reviewed by Wieckowski. ... 

Flory-Huggins-type isotherms and the Bockris-Swinkels isotherm in particular. If n is assumed equal to 3 in the latter case, the value of 01 becomes 0.582." ... 

Woods, R., 1996. Chemisorption of thiols on metal and metal sulphide. In J. O M Bockris, B. E. Conway, R. E. White (eds.). Modem Aspects of Electrochemistry. 29 401 - 453 Woods, R., Young, C. A., Yoon, R. H., 1990. Ethyl xanthate chemisorption isotherms andEh-pH diagrams for the copper/water/xanthate and chalcocite/water/xanthate systems. Inter. J. Miner. Process, 30 17 - 33... 

Irreversible reaction, 1251, 1419 Isoconic, definition, 933, 978, 982 Isotherm, 932, 964, 1197 applicability, 941 and charge transfer, 954, 955 Conway and Angersein-Kozlowska, 943 definition, 933 in electrode kinetics, 1197 Flory—Huggins type, 941,942, 944, 965 Frumkin, 938, 942, 965 Frumkin-Temkin, 1197, 1198 Habib-Bockris, 943... 

Standard states of species adsorbed on the surface and in solution have been given a lot of thought by scientists in the area (Conway, 1974 Nikitas, 1984 Bockris, 1986 Trasatti, 1987). The importance of finding convenient standard states is that in doing so we are able to compare the adsorption energies of different adsorption processes calculated by different isotherms. 

The isotherm derived by Bockris, Devanathan, and Muller (BDM) is centered around the role of the water in the interphase. 

Bockris and co-workers (317-320) conducted systematic studies on a variety of perovskite oxide catalysts in alkaline solutions and found the kinetics of the OER to have no functional dependence on the semiconductor-type properties of these oxides. The kinetics were found to improve with a decrease of magnetic moment, with a decrease of the enthalpy of formation of transition metal hydroxides, and with an increase in the number of d electrons in the transition metal ion. Thus, it has been suggested that, on the series of perovskites, there is a common slow step, OH desorption, with the differing —OH bond strength giving different isotherms and hence b values (i.e.. 

Recently Bockris etal. 11) proposed an isotherm for ionic adsorption, taking into account interaction forces between the adsorbed ion and its image and with the neighboring adsorbed ions. The isotherm may be represented by... 

The most important macroscopic and statistical thermodynamic models developed to describe adsorption phenomena on electrodes are presented critically in a concise and authoritative chapter by Panos Nikitas. The reader is guided through the seminal contributions of Frumkin, Butler, Bockris, Guidelli and others, to the current state of the art adsorption isotherms, which are both rigorous, and in good agreement with experiment. 

Bockris, Devanathan and Muller (B.D.M.) in 1963 modified the Langmuir isotherm to take into account the dependence of the Langmuir constant (equation 20.19) on potential and coverage. The B.D.M. isotherm allows for the interaction of the adsorbed ions, which are assumed to be confined to the... 

A more elaborate theory of orientation effects was developed by Watts-Tobin and Mott and applied by Bockris, Devanathan, and Muller and Bockris and Habibto the calculation of isotherms for adsorption of organic substances. Solvent molecules were regarded as being present in the double layer in two orientations, up or down (cf. theories of ferromagnetism) at respective surface coverages of N or N[. The sum iVf + is equal to the total coverage of the electrode by solvent molecules. 

Also, in further developments of this kind of treatment, specific structureforming and structure-breaking effects of the organic adsorbate must be considered in relation to the orientation of solvent molecules, e.g., as indi-cated by entropies and heats of adsorption of pyridine at Hg electrodes. Analysis of various types of isotherms which represent organic molecule adsorption has been made by Kovac and Bockris and by Wroblowa and Mueller in relation to the theory presented above. 

Figure 8. Adsorption isotherms for ethylene on Pt electrodes [from Gileadi, Rubin and Bockris, J. Phys. Chem. 69 (1965) 3335J.

A recent study " of the electrosorption of ethylene on Pt electrodes from 1 N sulfuric acid showed that a limiting coverage of 0 == 0.4 was reached when the concentration of ethylene in solution exceeded 10" moles/liter. The adsorption isotherm obtained at 30°C and a potential of 0.4 V (N.H.E.) is shown in Figure 8. The variation of partial coverage at extreme values of the potential was interpreted in terms of a competition with water model proposed by Bockris et The low value of... 

Bockris and co-workers [110, 119-123] attribute primary importance to the competition between the organic compound and water molecules for sites on the surface. This conclusion is based on determination of heats and entropies of adsorption by analysis of adsorption isotherms obtained by a tracer method. However, the theories put forward in these papers do not take adequate account of all the experimental results reported for adsorption phenomena at platinum electrodes. 

Heiland, Gileadi, and Bockris [120,121] used the Frumkin isotherm to describe the adsorption of benzene on platinum in solutions of sulfuric and phosphoric acids. 

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