Fuel cell cathode catalyst

Paradoxically, all these significant recent contributions to the theory of the ORR, together with most recent experimental efforts to characterize the ORR at a fuel cell cathode catalyst, have not led at aU to a consensus on either the mechanism of the ORR at Pt catalysts in acid electrolytes or even on how to properly determine this mechanism with available experimental tools. To elucidate the present mismatch of central pieces in the ORR puzzle, one can start from the identification of the slow step in the ORR sequence. With the 02-to-HOOads-to-HOads route appearing from recent DFT calculations to be the likely mechanism for the ORR at a Pt metal catalyst surface in acid electrolyte, the first electron and proton transfer to dioxygen, according to the reaction... 

Jasinski R. 1964. A new fuel cell cathode catalyst. Nature 201 1212. 

Alternative cathode catalysts to platinum have been the focus of many researchers over the past four decades. Numerous reviews have been published on various aspects and types of PEM fuel cell cathode catalysts.2,7-21 In this work we review the major classes of non-noble metal ORR catalysts in acidic electrolytes. The techniques used to study the catalysts, a brief history of catalyst development including major breakthroughs, and possible future directions will be discussed. 

Wang, G., Mukherjee, P P, and Wang, C. Y. Optimization of polymer electrolyte fuel cell cathode catalyst layers via direct numerical simulation modeling. Electrochimica Acta 2007 52 6367-6377. 

Zelenay et al. explored Co-polypyrrole (CoPPy) material as a PEM fuel-cell cathode catalyst. The composite CoPPy catalyst, even without a heat treatment, could generate a power density of 0.15Wcm in a H2—O2 fuel cell and displayed no signs of performance degradation for more than 100 h. Their results showed that heteroatomic polymers can be used not only to stabilize the non-noble metals in a PEM fuel cell environment but also to generate active sites for the ORR. Study of the interaction between the catalyst and oxygen also demonstrated that CoPPy... 

Maruyama J, Abe I (2007) Fuel cell cathode catalyst with Heme-like structure formed from nitrogen of glycine and iron. J Electrochem Soc 154 B297-B304... 

The ORR activities on various metallic catalysts have been widely studied by RDE or RRDE in alkaline media [28-48], as briefly summarized here. Several precious metals and their alloys are known to promote the 4e ORR pathway. The kinetics of ORR on the surfaces of nanoparticles of various metals dispersed on high-surface area carbon determined by the RDE technique in 0.1 M NaOH solutions are shown in Fig. 15.3 [29]. Among the tested metallic catalysts, Pd/C seems to be the most promising alternative to Pt/C. Detailed comparisons of the ORR activity of Pd/C and Pt/C catalysts in alkaline solutimis revealed that the activation energy for the ORR on Pd/C was slightly lower than that on Pt/C (39 vs. 48 kJ mol at an overpotential of 300 mV) [30]. The 4e pathway was dominant on both the Pt/C and the Pd/C catalysts. As shown in Fig. 15.4, ORR was more favorable on a clean Pd surface than on a clean ft surface however, Pd was more easily oxidized at fuel cell cathode working potentials (Fig. 15.5). One of the merits of the Pd/C catalyst is that it is less sensitive to ethanol presented in the electrolyte as compared to the Pt/C [30]. To use the Pd, a realistic fuel cell cathode catalyst in the alkaline media, the problem of Pd oxidization at fuel cell cathode working potentials needs to be resolved. 

U.S. Department of Energy s 2014 Atmual Merit Review and Peer Evaluation Meeting Presentation (2014) Non-precious metal fuel cell cathodes catalyst development and electrode strucmre design, http //www.hydrogen.energy.gov/pdfs/review 14/fc 107 zelenay 2014 o.pdf... 

Dutta M, Jia N, Lu S, Colbow V and Wessel S (2010), Effects of Upper Potential Dwell Time, Transients and Relative Humidity on PEM Fuel Cell Cathode Catalyst Degradation , Abs. 0543.pdf, 217th Meeting (c) 2010 The Electrochemical Society. 

Kundu S, Cimenti M, Lee S and Bessarabov D (2009), Fingerprint of automotive fuel cell cathode catalyst degradation Pt band in VEMs, Membrane Technology, October 2009, 7-10. 

Xie, Z., Zhao, X., Adachi, M., Shi, Z., Mashio, T., Ohma, A., Shinohara, K., Holdcroft, S., and Navessin, T. 2008. Fuel cell cathode catalyst layers from green catalyst inks, Envimn. ScL. 1, 184-193. 

F. Jaouen, E. Proietti, M. Lefevre, R. Chenitz, J.-P. Dodelet, G. Wu, et al.. Recent advances in non-predous metal catalysis for oxygen-reduction reaction in polymer electrolyte fuel cells. Energy Environ. Sd. 4 (2011) 114-130. R. Jasinski, A new fuel cell cathode catalyst. Nature 201 (1964) 1212-1213. 

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