Electrocatalyst bimetallic

Apart from single electrocatalysts, bimetallic catalysts of noble and... 

Once we have developed our basic model and shown how it may be used to estab-hsh trends in electrochemical reactivity, we will take the further step of applying it to the identification of new bimetallic electrocatalysts. We will introduce simple procedures to rapidly screen bimetallic alloys for promising electrocatalytic properties, and we will demonstrate the importance of including estimates of the alloys stabihty in the screening procedure. Finally, we will give examples of successful apphcation of this method to specific problems in the area of electrocatalyst development. 

Markovic NM, Radmilovic V, Ross PN. 2003. Physical and electrochemical characterization of bimetallic nanoparticle electrocatalysts. In Wieckowski A, Savinova E, Vayenas C, eds. Catalysis and Electrocatalysis at Nanoparticle Surfaces. New York Marcel Dekker, pp. 311-342. 

Maroun F, Ozanam F, Magnussen OM, Behm RJ. 2001. The role of atomic ensembles in the reactivity of bimetallic electrocatalysts. Science 293 1811-1814. 

Wang W, Zheng D, Du C, Zou Z, Zhang X, Xia B, Yang H, Akins DL. 2007. Carbon-supported Pd-Co bimetallic nanoparticles as electrocatalysts for the oxygen reduction reaction. J Power Sources 167 243-249. 

Leger JM, Rousseau S, Coutanceau C, Hahn E, Lamy C. 2(X)5. How bimetallic electrocatalysts does work for reactions involved in fuel cells Example of ethanol oxidation and comparison to methanol. Electrochim Acta 50 5118-5125. 

Electrocatalyst see also specific catalysts adsorbate-support interactions, 30 273-279 adsorption, 30 240-264 isotherms, 30 241-243 bimetallic activity, 30 275... 

Heteronuclear Pt-Ru binary carbonyl clusters have been used for the preparation of tailored PtRu bimetallic electrocatalysts. The use of carbonyl complexes such as Ru4Pt2(CO)i8 and closely related carbide and hydride carbonyl-derived clusters, that is, Ru5PtC(CO)i6 and Ru6Pt3(CO)2i( X3-H)( x-H)3, has allowed the preparation of carbon- and y-Al203-supported catalysts in which the presence of RugPts, RusPt and Ru4Pt2 clusters or nanoparticles has been reported [62-65]. 

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... 

Figure 3.3.13 (A) Pt core-shell nanoparticle ORR electrocatalysts are prepared by (electro) chemical selective removal of a less noble metal, M, from a Pt-M nanoparticle alloy. The near-surface region is Pt enriched, while the particle core remains bimetallic. (B) Transmission electron microscopic elemental map of dealloyed Pt-Cu core-shell nanoparticle ORR electrocatalysts.

Teliska, M. et al.. Correlation of water activation, surface properties, and oxygen reduction reactivity of supported Pt-M/C bimetallic electrocatalysts using XAS, J. Electro-chem. Soc., 152, A2159, 2005. 

Adsorption and Electro-Oxidation of CO at Platinnm Based Bimetallic Electrocatalysts... 

Chapter 4, by Batzill and his coworkers, describes modern surface characterization techniques that include photoelectron diffraction and ion scattering as well as scanning probe microscopies. The chapter by Hayden discusses model hydrogen fuel cell electrocatalysts, and the chapter by Ertl and Schuster addresses the electrochemical nano structuring of surfaces. Henry discusses adsorption and reactions on supported model catalysts, and Goodman and Santra describe size-dependent electronic structure and catalytic properties of metal clusters supported on ultra-thin oxide films. In Chapter 9, Markovic and his coworkers discuss modern physical and electrochemical characterization of bimetallic nanoparticle electrocatalysts. 

Bonnemann and Richards lead off the section on synthetic approaches with a discussion of nanomaterials as electrocatalysts to tailor structure and interfacial properties. Teranishi and Toshima as well as Simonov and Likholobov discuss preparation and characterization of supported monometallic and bimetallic nanoparticles. 

Lambert reviews the role of alkali additives on metal films and nanoparticles in electrochemical and chemical behavior modihcations. Metal-support interactions is the subject of the chapter by Arico and coauthors for applications in low temperature fuel cell electrocatalysts, and Haruta and Tsubota look at the structure and size effect of supported noble metal catalysts in low temperature CO oxidation. Promotion of catalytic activity and the importance of spillover are discussed by Vayenas and coworkers in a very interesting chapter, followed by Verykios s examination of support effects and catalytic performance of nanoparticles. In situ infrared spectroscopy studies of platinum group metals at the electrode-electrolyte interface are reviewed by Sun. Watanabe discusses the design of electrocatalysts for fuel cells, and Coq and Figueras address the question of particle size and support effects on catalytic properties of metallic and bimetallic catalysts. 

Part III presents the state of the art of the synthesis of nanoparticle catalysts and electrocatalysts, including bimetallic nanoparticles. Particular emphasis is given to carbon-supported nanoparticles due to their technological signihcance in the fabrication of electrodes for PEM fuel cells. 

Physical and Electrochemical Characterization of Bimetallic Nanoparticle Electrocatalysts... 

Bimetallic Pt-Sn catalysts are useful commercially, e.g., for hydrocarbon conversion reactions. In many catalysts, Pt-Sn alloys are formed and play an important role in the catalysis. This is particularly true in recent reports of highly selective oxidative dehydrogenation of alkanes [37]. In addition, Pt-Sn alloys have been investigated as electrocatalysts for fuel cells and may have applications as gas sensors. Characterization of the composition and geometric structure of single-crystal Pt-Sn alloy surfaces is important for developing improved correlations of structure with activity and/or selectivity of Pt-Sn catalysts and electrocatalysts. 

In this chapter we review studies, primarily from our laboratory, of Pt and Pt-bimetallic nanoparticle electrocatalysts for the oxygen reduction reaction (ORR) and the electrochemical oxidation of H2 (HOR) and H2/CO mixtures in aqueous electrolytes at 274—333 K. We focus on the study of both the structure sensitivity of the reactions as gleaned from studies of the bulk (bi) metallic surfaces and the resultant crystallite size effect expected or observed when the catalyst is of nanoscale dimension. Physical characterization of the nanoparticles by high-resolution transmission electron microscopy (HRTEM) techniques is shown to be an essential tool for these studies. Comparison with well-characterized model surfaces have revealed only a few nanoparticle anomalies, although the number of bimetallics... 

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