Anode Catalyst Layer Degradation-Voltage Reversal

2 Anode Catalyst Layer Degradation-Voltage Reversal 

Oxygen starvation caused by air stoichiometry or electrode flooding can lead to cell reversal. When there is insufficient oxygen at the cathode to combine with the protons coming across the membrane, the oxygen reduction reaction (ORR) 

Voltage reversal caused by fuel starvation has been observed both in stack applications and in controlled laboratory experiments [61]. Many factors, such as severe water flooding, stack manifold problems, and flow field blockage, particularly at a low pressure drop across the cells, can cause localized fuel starvation. If hydrogen is no longer available to be oxidized, the voltage at the anode will rise to that required to oxidize water (electrolysis). The electrolysis of 

EiMUitced wBier teUfilidA lAddttiMai PTFE i Standtoii caiWysl 

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Figure 17.5. The dependence of the Pt ratio to Ru, Pt/(Ru + Pt), of the anode catalyst layer after the cell voltage reversal experiment for 2 min, determined by EDX on the sample location [19]. (Reprinted from Journal of Power Sources, 130(1-2), Taniguchi A, Akita T, Yasuda K, Miyazaki Y, Analysis of electrocatalyst degradation in PEMFC caused by cell reversal during fuel starvation, 42-9, 32004, with permission from Elsevier.)...

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