At platinum, analyses of the galvanostatic V --q transients (q = it) at various current densities and the dV/dq dependence on log i in H2SO4 solutions of different pH's have shown that, following the initial oxygen adsorption stage, the growth of the anodic oxide film in the potential reglon before significant oxygen evolution starts satisfies the Cabrera-Mott formalism of the high field assisted formation of ions and their migration through the oxide phase. For different current densities, the linear V --q lines intercept at a negative value of charge, qo. This charge is associated with oxygen adsorption at oxide-free surfaces before the onset of oxide film formation. Because the coverage with adsorbed oxygen at oxide surfaces is low, the charge for the initial adsorption at oxide-free surface has to be taken into account in considering the thickness of the oxide film and its growth. Analysis further shows that the exchange current density, to, and Tafel parameters, l/a, in the rate equation for growth are not dependent on pH. The only parameter that depends on pH is the potential Vo at which the V --q traces at various constant current densities in a solution of the same pH intercept in extrapolation, i.e., Vo -~ Voo --(2.3RT/F)pH, where Voo is a constant independent of pH. Vo signifies ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 142.58.129.109 Downloaded on 2015-06-05 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 142.58.129.109 Downloaded on 2015-06-05 to IP

The preparation of polycrystalline n-type iron oxide electrodes by heating of iron samples in air is reported. The behavior of these electrodes in aqueous solutions of different pH values in the presence and absence of illumination is shown. The photocurrent response of these electrodes to all wavelengths in the visible region is seen. Photoassisted electrolysis of water occurs at these wavelengths resulting in the evolution of oxygen bubbles at the iron oxide electrodes with no noticeable corrosion problems in pH 4.0 acetate buffer to 5.5M KOH solutions * Electrochemical Society Student Member. ? Electrochemical Society Honorary :Member.

P=2, R: 10 0 2 4 6 8 1 0 1 2 1 4 6 Figure 8. Graphs of y/yo vs. 6 compujed for R = 1 and various values of p with K = m (solid curves) and K = 2,lO (dotted curves).finite constant asymptotically at long time. Figure 8 shows the dependence of eq 20 on the choice of p for the case R = 1. Included as dotted curves are examples calculated from eq 17 for the unrestricted mechanism. Cases in which R # 1 are qualitatively similar to those shown. It is clear from this discussion that in the context of the Langmuir-Rideal mechanism it is not generally possible to view the quantity y as a constant attribute of the catalytic surface, since it depends not only on rate constants and active surface site density but also on the instantaneous values of fractional site coverage and atom concentration.

The reduction of the diactivated olefins dimethyl fumarate (DMeF), diethyl fumarate (DEF), di-n-butyl fumarate (DBF), dimethyl maleate (DMM), diethyl maleate (DEM), and di-n-butyl maleate (DBM), in N,N-dimethylformamidetetra-n-butylammonium iodide solutions saturated with disso]ved carbon dioxide at a platinum electrode has been studied by rotating ring-disk electrode and cyclic voltammetry and in situ electron spin resonance spectroscopy. ABSTRACTThe exchange reaction at polycrvstalline silver electrodes has been investigated for the system Ag-AgNO3-KNOs using a faradaic impedance method. The exchange reaction was determined to be adatom diffusion controlled and the exchange current was found to be dependent on pH. It is suggested that

No abstract