Degradation oxygen starvation

In summary, we conclude that oxygen starvation results in a slightly negative cell voltage and hydrogen production at the cathode side. The simultaneous power loss is reversible and the mechanism does not lead to cell degradation since high electrode potentials required for carbon corrosion or platinum dissolution do not... 

Measurement of the single cell voltages in a stack allows the detection of cell reversals due to overall hydrogen or oxygen starvation. As soon as the minimum cell voltage falls below a given lower limit, it is possible to prevent cell degradation by reduction of the cell current. 

Starvation in fish appears to be characterised by basal levels of protein synthesis and elevated rates of protein degradation. A decline in the rates of protein synthesis with starvation has been described in a number of fish species (Jackim and La Roche 1973 Smith and Haschemeyer 1980 Smith 1981 Haschemeyer 1983 Lied et al. 1983 Pocrnjic et al. 1983 Loughna and Goldspink 1984 Fauconneau et al. 1986 Houlihan et al. 1988b Watt et al. 1988). It has frequently been suggested that the reduction in oxygen consumption which accompanies starvation is partly due to a reduction in protein synthetic rates (Smith and Haschemeyer 1980 Smith 1981 Lied et al. 1982). 

In addition to the increased water content of the electrodes, the membrane gas cross-over is also increased at a high membrane water content. This may accelerate electrode degradation mechanisms such as carbon corrosion due to partial fuel starvation, which is influenced by the cross-over of oxygen to the anode (see Section 6.4.2). 

Fuel starvation can very rapidly degrade cell performance. If any portion of the anode is starved of hydrogen, the electrode potential will rise to oxygen evolution, and irreversible oxidation of the carbon support, substrate, and separator plate will ensue. To eliminate this, the anode flow fleld often has several passes, so that the hydrogen concentration is not reduced to low values in any locations [45]. 

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