A review of the main mechanisms of catalyst layer degradation in a polymer electrolyte membrane fuel cell (PEMFC) and diff erent performance recovery methods

This paper reviews over 100 articles on the subject of the mechanism of catalyst layer (CL) degradation and the eff ect of various types of contamination in the polymer electrolyte membrane fuel cell (PEMFC). Also, the recovery of PEMFC via diff erent types of methods, the causes and fundamental mechanisms of cell degradation, and their infl uence on long-term performance of PEM fuel cells is discussed in this review paper. The most important mechanism of CL degradation in PEMFC includes the eff ect of diff erent contaminations such as carbon monoxide, carbon dioxide, hydrogen sulphide, sulfur dioxide, N􀹗, NO􀶑( NO, NO􀹗), SO􀶑 (SO, SO􀹘), and ammonia. In this study, the agglomeration of catalyst, reactant gas starvation, and oxide and hydroxide formation are investigated. As some of these CL degradations procedures are reversible, diff erent recovery methods for retrieving the catalyst electrochemical active surface area (ECSA) are presented. Some of these recovery methods, including recovery by H􀹗 purge, direct and indirect zone, short circuit method, water steam, and the reduction method, are presented in this review article. The review results show that the high and eff ective performance of the PEMFC was achieved by applying ozone method, water steam, and reduction method. However, only H2 purge and reduction methods are applicable to a stack of fuel cells. Therefore, in light of the facts outlined above, it is safe to conclude that the reduction method is one of the most eff ective methods for the recovery of reversible CL degradations. Finally, a fl owchart of the studied cell degradation and its recovery is presented at the end of the paper. This review was focused on the degradation mechanism of the catalyst layer from diff erent research aspects such as contamination’s impact on the performance of a fuel cell, various mechanism approaches, and mitigation development. As the result, we hope that this brief overview provides a good perspective of the important issues that engineers and researchers in this fi eld should address to extend the lifetime and durability of the next-generation of fuel cells.