Degradation cathode kinetics

The corrosion potential, ECOrr, adopted by the system will be dictated by the relative kinetics of the anodic material degradation process and the cathodic reduction kinetics of the oxidant. While ECOrr yields no quantitative information on the rate of the overall corrosion process, its value, and how it changes with time, is a good qualitative indication of the balance in corrosion kinetics and their evolution with time. Thus a knowledge of ECOrr and its comparison to ther-... 

MEA performance is mainly limited by ORR kinetics, as well as oxygen transport to the cathode catalyst. Another major loss is due to proton conduction, in both the membrane and the cathode catalyst layer (CL). Characterization of the ionic resistance of fuel cell electrodes helps provide important information on electrode structure optimization, and quantification of the ionomer degradation in the electrodes [23],... 

On the Osaka University thermionic cathode L-band linac, a time resolution of two picoseconds was achieved using magnetic pulse compression and time jitter compensation systems (Fig. 13). The time jitter between the Cerenkov light from the electron beam and the laser pulse was measured shot-by-shot with a femtosecond streak camera to accurately determine the relative time of each measurement in the kinetic trace. In this way, the time jitter that would otherwise degrade the time resolution was corrected, and the remaining factor dominating the rise time was the electron-light velocity difference over the 2-mm sample depth. 

It is obvious that in case of a defect down to steel, which leads to the enhanced anodic dissolution of zinc, the delamination of the purely alkaline cleaned galvanized steel surface is not faster than that of a phosphated surface. Such a behavior can be explained by an anodic delamination process. If the corrosion conditions are such that no formation of a cathode is possible in front of the anode, then just the kinetics of zinc dissolution determine the degradation of the polymer-metal composite. 

Figure 8.24 shows the model capabilities to address competitive degradation phenomena membrane chemical degradation makes the proton conductivity decrease and thus potential cathode decreases which in turn decreases the kinetics of the cathode Pt degradation. In other words, membrane degradation can mitigate Pt degradation in the cathode, under specific operation conditions. 

Yokokawa, H., Sakai, N., Horita, T., Yamaji, K., Brito, M.E., and Kishimoto, H. (2008) Thermodynamic and kinetic considerations on degradation in solid oxide fuel cell cathodes, f. Alloys Comvd., 452, 41-47. 

Yokokawa H, Sakai H, Horita T, Yamaji K, Brito ME, Kishimoto H (2008) Thomodynamic and kinetic considerations on degradations in solid oxide fnel cell cathodes. J Alloy Comp... 

Toluene contamination in air could affect fuel eell performanee, mainly resulting in performance degradation in the kinetic region (low current densities). This contamination also results in easy flooding at the cathode side, possibly changing the hydrophilicity of the cathode eatalyst layer. The mechanism of toluene contamination is not clear [56]. 

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