Cathode surface characterization

Surface characterization includes also the study of the modification of a surface under cathodic load or after some pretreatments. The presence of residual surface oxides can explain some observations otherwise inexplicable. Activation in situ usually results in composite structures which are difficult to identify by X-ray, and may contain metallic and non-metallic components. Particularly crucial is the case of the surface structure of glassy metals or amorphous alloys. 

Bockris et al. [87, 290, 291] have recently reported results of a comprehensive program of surface characterization of a large number of perovskite oxide electrodes in oxygen evolution investigations. Anodic and cathodic oxygen reactions were studied in detail as a function of the solid-state surface properties of these materials. Capacity-potential curves were analysed in terms of the Mott-Schottky treatment and indicated that the potential distribution in the oxide corresponds to a depletion of electrons at the oxide electrode surface in the potential region where oxygen reduction... 

F. T. Quinlan, K. Sano, T. Willey, R. Vidu, K. TasaM, P. Stroeve, Surface Characterization of the Spinel LixMn204 Cathode before and after Storage at Elevated Temperatures, Chem. Mater. 2001, 13,4207-4212. 

Quinlan FT, Sano K, Willey T, Vidu R, TasaM K, Stroeve P (2001) Surface characterization of the spinel LixMn204 cathode before and after storage at elevated temperatures. Chem Mater 13 4207 212... 

Even though the lamp looks like a conventional arc lamp, it has been optimized to run in the so-called hot-spot mode . This discharge mode is characterized by the appearance of an extremely small plasma spot close to the cathode surface, in contrast to the typical diffuse arc shape of the common xenon lamps (refer to Figure 3.1). The plasma contraction is substantially achieved by selection of sophisticated materials for the anode and cathode rods, a short electrode distance (< 1 mm), an increased xenon pressure (about... 

Optical microscopy used to characterize the micromorphologies of the sample surface (e.g. electrode cathode surface after the arc discharge) or... 

Most organic reactions are Lewis acid/base processes that involve the interaction of a nucleophilic center with an electrophilic center. Because electrochemistry provides the ultimate nucleophile via the electrons at the cathode surface and the ultimate electrophile via the electron holes at the anode surface, it is the ideal methodology for the characterization of the electrophilicity and nucleophilic-ity of molecules. Thus, the carbon centers of saturated hydrocarbons (e.g., CH4) are resistant to electrochemical reduction and oxidation because of their inert nature (all valence electrons are stabilized in sigma bonds an absence of any Lewis acid/base character). However, organic molecules with electrophilic components [e.g., alkyl-, aryl-, and acyl- halides carbonyl groups unsaturated and aromatic hydrocarbons nitro groups Brpnsted... 

Therefore, the surface characterization of these sputtered polymers, and the investigation of the effects of selected sputtering conditions (gas pressure, gas composition, cathode selfbias voltage and cathode to specimen distance) on the structure and composition of these films were performed for the first time. Some information is also deduced on the mechanism of the sputter-ing-deposition of the films. 

Paradoxically, all these significant recent contributions to the theory of the ORR, together with most recent experimental efforts to characterize the ORR at a fuel cell cathode catalyst, have not led at aU to a consensus on either the mechanism of the ORR at Pt catalysts in acid electrolytes or even on how to properly determine this mechanism with available experimental tools. To elucidate the present mismatch of central pieces in the ORR puzzle, one can start from the identification of the slow step in the ORR sequence. With the 02-to-HOOads-to-HOads route appearing from recent DFT calculations to be the likely mechanism for the ORR at a Pt metal catalyst surface in acid electrolyte, the first electron and proton transfer to dioxygen, according to the reaction... 

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