Catalyst layer degradation

One of the critical issues with regard to low temperamre fuel cells is the gradual loss of performance due to the degradation of the cathode catalyst layer under the harsh operating conditions, which mainly consist of two aspects electrochemical surface area (ECA) loss of the carbon-supported Pt nanoparticles and corrosion of the carbon support itself. Extensive studies of cathode catalyst layer degradation in phosphoric acid fuel cells (PAECs) have shown that ECA loss is mainly caused by three mechanisms ... 

Contact angle measurements on the CL may also be useful in the characterization of catalyst layer degradation in a fuel cell. Yu et al. [19] found that the contact angle of a degraded CL became smaller compared to that of an unused catalyst layer, indicating more hydrophilic behavior accompan3dng degradation. 

An important supplementary tool for performance analysis of PEFC electrodes is the study of the complex impedance, as it provides a tool to monitor changes of electrode function upon variation of its composition. It can help to detect in real time the structural changes due to spontaneous or current-induced repartitioning of the elements of the porous dual percolation network, that could lead to phase segregation and catalyst layer degradation. 

Zhang S, yuan XZ, Cheng Hin JN, Wang H (2009) A review of platinum-based catalysts layer degradation in proton exchange membrane fuel cells. J Power Sources 194 588-600... 

Zhang S, Yuan X Z, Cheng Hin J, Wang H, Wu J, Friedrich K A and Schulze M (2010), Effects of open-circuit operation on membrane and catalyst layer degradation in proton exchange membrane fuel cells. Journal of Power Sources, 195,1142-1148. 

As a summary, we conclude that overall hydrogen starvation results in negative cell voltage and carbon corrosion in addition to water oxidation within the anode catalyst layer. Degradation reaction rates increase with decreasing fuel stoichiometry. 

In total, electric energy, water, and heat are produced. However, additional and undesired reactions can produce catalyst layer degradation and consequently can limit the lifetime of the fuel cell. Carbon corrosion and dissolution of the active metal catalyst are the main undesired side reactions in PEFCs [62-66]. 

Catalyst Layer Degradation, Diagnosis and Failure Mitigation... 

Diagnosis of Catalyst Layer Degradation Fuel Cell Failure Analysis... 

A fuel cell is a typical electrochemical device. Thus, the electrochemical analysis methods developed for other electrochemical devices can be directly used or modified for diagnosis of fuel cell degradation, including catalyst layer degradation. Cyclic voltammetry and polarization curve analysis are very frequently used in failure analysis and degradation diagnosis. 

Electrochemical methods used in the diagnosis of fuel cell degradation provide directly macro-phenomena about fuel cell degradation. Hypothesis and degradation mechanisms can be deduced from electric measurement results, e.g., from analysis of polarization curves. To fundamentally understand catalyst layer degradation in... 

Anode Catalyst Layer Degradation Caused by Contamination... 

Anode Catalyst Layer Degradation-Voltage Reversal... 

The performanee and durability of a membrane electrode assembly (MEA) is affected signifieantly by the eathode eleetrode eomposition and structure, due to the poor kineties of oxygen reduetion and reaetant transport limitations. Utilization and stability of platinum or its alloys in the PEMFC play important roles in fuel cell efficiency, durability, and the drive for eost reduction through reduced Pt loadings. Cathode catalyst layer degradation is a critical issue for fuel cell durability to meet the requirement of > 5000 hours for automotive applications and > 40,000 for stationary applications. 

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