Polymer-electrolyte-membrane fuel cell electrocatalysts

Wang, Y.J., Wilkinson, D.P Zhang, X Noncarbon support materials for polymer electrolyte membrane fuel-cell electrocatalysts. Chem. Rev. Ill (2011), pp. 7625-7651. 

Electro-catalysts which have various metal contents have been applied to the polymer electrolyte membrane fuel cell(PEMFC). For the PEMFCs, Pt based noble metals have been widely used. In case the pure hydrogen is supplied as anode fuel, the platinum only electrocatalysts show the best activity in PEMFC. But the severe activity degradation can occur even by ppm level CO containing fuels, i.e. hydrocarbon reformates[l-3]. To enhance the resistivity to the CO poison of electro-catalysts, various kinds of alloy catalysts have been suggested. Among them, Pt-Ru alloy catalyst has been considered one of the best catalyst in the aspect of CO tolerance[l-3]. 

There are a few distinct structural concepts for high-performance Pt alloy ORR electrocatalysts that are currently attracting much attention because they hold the promise of significant activity improvements compared to pure Pt catalysts. As a result of this, these electrocatalysts potentially offer the prospect to impact the future of Polymer Electrolyte Membrane fuel cell catalyst technology. 

The SECM capacity for rapid screening of an array of catalyst spots makes it a valuable tool for studies of electrocatalysts. This technique was used to screen the arrays of bimetallic or trimetallic catalyst spots with different compositions on a GC support in search of inexpensive and efficient electrocatalytic materials for polymer electrolyte membrane fuel cells (PEMFC) [126]. Each spot contained some binary or ternary combination of Pd, Au, Ag, and Co deposited on a glassy carbon substrate. The electrocatalytic activity of these materials for the ORR in acidic media (0.5 M H2S04) was examined using SECM in a rapidimaging mode. The SECM tip was scanned in the x—y plane over the substrate surface while electrogenerating 02 from H20 at constant current. By scanning... 

Mani P, Srivastava R, Strasser P. Dealloyed binary PtM3 (M = Cu, Co, Ni) and ternary PtNbM (M = Cu, Co, Fe, Cr) electrocatalysts for the oxygen reduction reaction performance in polymer electrolyte membrane fuel cells. J Power Sources. 2011 196 666-73. 

Carmo M, Roepke T, Roth C, dos Santos AM, Poco JGR, Linardi M (2009) A novel electrocatalyst support with proton conductive properties for polymer electrolyte membrane fuel cell applications. J Power Sources 191 330-337... 

Recently, taking advantage of the very narrow size distribution of the metal particles obtained, microemulsion has been used to prepare electrocatalysts for polymer electrolyte membrane fuel cells (PEMFCs) Catalysts containing 40 % Pt Ru (1 1) and 40% Pt Pd (1 1) on charcoal were prepared by mixing aqueous solutions of chloroplatinic acid, ruthenium chloride and palladium chloride with Berol 050 as surfactant in iso-octane. Reduction of the metal salts was complete after addition of hydrazine. In order to support the particles, the microemulsion was destabilised with tetrahydrofurane in the presence of charcoal. Both isolated particles in the range of 2-5 nm and aggregates of about 20 nm were detected by transmission electron microscopy. The electrochemical performance of membrane electrode assemblies, MEAs, prepared using this catalyst was comparable to that of the MEAs prepared with a commercial catalyst. 

Electrocatalysts in Polymer Electrolyte Membrane Fuel Cells (PEMFC) and PAFC... 

Heinzel and Konig snmmarize the impact of nanostrnctnred materials on fnel cell technology, mainly in the area of polymer electrolyte membrane fuel cells. This chapter illustrates how nanostructured materials can modify component performance snch as electrocatalyst materials and membrane. 

For polymer electrolyte membrane fuel cell (PEMFC) applications, platinum and platinum-based alloy materials have been the most extensively investigated as catalysts for the electrocatalytic reduction of oxygen. A number of factors can influence the performance of Pt-based cathodic electrocatalysts in fuel cell applications, including (i) the method of Pt/C electrocatalyst preparation, (ii) R particle size, (iii) activation process, (iv) wetting of electrode structure, (v) PTFE content in the electrode, and the (vi) surface properties of the carbon support, among others. ... 

Polymer electrolyte fuel cells, also sometimes called SPEFC (solid polymer electrolyte fuel cells) or PEMFC (polymer electrolyte membrane fuel cell) use a proton exchange membrane as the electrolyte. PEEC are low-temperature fuel cells, generally operating between 40 and 90 °C and therefore need noble metal electrocatalysts (platinum or platinum alloys on anode and cathode). Characteristics of PEEC are the high power density and fast dynamics. A prominent application area is therefore the power train of automobiles, where quick start-up is required. 

Oezaslan M, Strasser P (2011) Activity of dealloyed P1C03 and P1CU3 nanoparticle electrocatalyst for oxygen reductirar reaction in polymer electrolyte membrane fuel cell. J Power Sources 196(12) 5240-5249... 

CO preferential oxidation (CO-PROX) has been investigated in order to remove the trace amounts of CO in H2 rich stream, as remaining traces of CO in H2 can easily poison the Pt based anode electrocatalyst of polymer electrolyte membrane fuel cells (PEMFC). 

In recent years, fuel cells have attracted considerable attention due to their high energy efficiency with zero emissions [1]. Electrocatalysts are some of the key materials used in low-temperature fuel cells such as the polymer electrolyte membrane fuel cell (PEMFC) and the direct methanol fuel cell (DMFC). Creating high-performance catalysts is widely recognized as a key step for the further development and commercialization of low-temperature fuel cells. 

Huang S-Y, Ganesan P, Popov BN (2012) Electrocatalytic activity and stability of titania-supported platinum-palladium electrocatalysts for polymer electrolyte membrane fuel cell. ACS Catal 2 825-831... 

Shi, M. and Anson, F. C. (1997) Dehydration of protonated Nafion coatings induced by cation exchange and monitoied by quartz crystal miciogravimetry. J. Electrcanal. Chem. 425, 117-123 Silva, R. F. and Pozio, A. (2(X)7) Corrosion study on different types of metedlic bipolar plates for polymer electrolyte membrane fuel cells. J. Fuel Cell Sci. Technol. 4, 116-122 Smotkin, E. S. and Dtaz-Morales, R. R. (2003) New electrocatalysts by combinatorial methods. Annu. Rev. Mater. Res. 33, 557-579... 

Kim HJ, Kim YS, Seo MH, Choi SM, Kim WB (2009) Pt and PtRh nanowire electrocatalysts for cyclohexane-fueled polymer electrolyte membrane fuel cell. Electrochem Commun 11(2) 446 49... 

Gupta, S., Tryk, D., Zecevic, S.K., Aldred, W., Guo, D., Savinell, R.F. (1998) Methanol-tolerant electrocatalysts for oxygen reduction in a polymer electrolyte membrane fuel cell. Journal of Applied Electrochemistry, 28, 673-682. 

The concept of a promoter can also be extended to the case of substances which enhance the performance of an electrocatalyst by accelerating the rate of an electrocatalytic reaction. This can be quite important for the performance, e.g., of low temperature (polymer electrolyte membrane, PEM) fuel cells where poisoning of the anodic Pt electrocatalyst (reaction 1.7) by trace amounts of strongly adsorbed CO poses a serious problem. Such a promoter which when added to the Pt electrocatalyst would accelerate the desired reaction (1.5 or 1.7) could be termed an electrocatalytic promoter, or electropromoter, but this concept will not be dealt with in the present book, where the term promoter will always be used for substances which enhance the performance of a catalyst. 

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