Platinum-based Alloy Catalysts for PEM Fuel Cells

Platinum-based Alloy Catalysts for PEM Fuel Cells 

HOR at the anode, in order to overcome the problem of catalyst poisoning caused by CO impurity in the hydrogen gas. 

It is generally recognized that the development of Pt-based alloys is one feasible strategy for Pt load reduction and activity enhancement in fuel cells, including both hydrogen-fuelled PEMFCs and DMFCs. In this chapter, we introduce the research and development of Pt-based alloy catalysts for both the ORR and the MOR. The alloying effect and corresponding mechanism as well as the stability of Pt-based alloy catalysts towards the ORR and MOR will be described in detail. The topics of CO- and methanol-tolerant Pt-based alloy catalysts will not be discussed in this chapter (please see instead Chapter 16, CO-Tolerant Catalysts ). 

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Platinum-based Alloy Catalysts for PEM Fuel Cells 637 13.2.2.2 The OHads Inhibition Effect... 

This selected brief review will be focused on the research and development progress on ORR kinetics. The origin of the problem related with the low ORR activity of platinum will be discussed, followed by a review of recent progress in making more active, more durable platinum-based ORR catalysts. These include platinum alloy catalysts, platinum monolayer catalysts, platinum nanowire and nanotube catalysts, and the more recent shape- and facet-controlled platinum-alloy nanocrystal catalysts. The progress in the mechanistic understanding on the correlation between the activity and the electronic and structural properties of surface platinum atoms will be reviewed as well. The future direction of the research on platinum-based catalysts for PEM fuel cell apphcation will be proposed. 

FIGURE 2.10 Non-noble metal dissolution data as a function of time for different Pt-alloy catalysts at a fixed potential of 0.8V vs. NHE. (Reproduced from /. Power Sources, 155, Col6n-Mercado, H. R. and Popov, B. N. Stability of platinum based alloy cathode catalysts in PEM fuel cells, 253-263, Copyright (2006), with permission from Elsevier.)... 

The electro-catalytic oxidation of hydrogen, and reduction of oxygen, at carbon supported platinum based catalysts remain essential surface processes on which the hydrogen PEM fuel cell relies. The particle size (surface structure) and promoting component (as adsorbate or alloy phases) influence the activity and tolerance of the catalyst. The surface chemical behavior of platinum for hydrogen, oxygen, and CO adsorption is considered, in particular with respect to the influence of metal adsorbate and alloy components on close packed and stepped (defect) platinum surfaces. Dynamical measurements (employing supersonic molecular beams) of the... 

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