Nanostructured electrocatalysts

A large number of experimental techniques have been explored for the atomistic characterization of electrocatalyst nanostructures and significant advances are made on understanding their unique structures and properties. The capabilities of diffraction, microscopy, and several spectroscopic techniques in realizing the physical properties and atomistic structures of electrocatalysts are reviewed in the following section. 

GustavssonM, Fredriksson H, Kasemo B, Jusys Z, Jun C, Behm RJ. 2004. Nanostructured platinum-on-carbon model electrocatalysts prepared by colloidal lithography. J Electroanal Chem 568 371-377. 

Jiang J, Kucemak A. 2002. Nanostructured platinum as an electrocatalyst for the electrooxidation of formic acid. J Electroanal Chem 520 64-70. 

Y. D. Jin, Y. Shen, and S. J. Dong, Electrochemical design of ultrathin platinum-coated gold nanoparticle monolayer films as a novel nanostructured electrocatalyst for oxygen reduction, J. Phys. Chem. B 108, 8142-8147 (2004). 

Direct metal deposition from metallic sources has been extensively used for model catalyst deposition for high-throughput and combinatorial studies. However, these methods are also increasingly used to deposit practical electrocatalyst materials. The best known approach is the one developed by 3M researchers have used physical vapor deposition to deposit Pt and Ft alloys onto nanostructured (NS) films composed of perylene red whiskers. The approach has been recently been reviewed by Debe. ... 

In conclusion, although results on the use of Ti02 nanotube array catalysts or electrocatalysts are still limited, the future is promising. In several cases, unusual behavior was demonstrated and associated with the specific characteristics of the nanostructure. 

From combined theoretical and experimental insights, nanostructured Pt core-shell electrocatalyst architectures have recently emerged as promising, cost-effective cathode fuel cell catalysts. Pt-enriched multilayer surface shells surround Pt-poor cores that modify the reactivity of the surface Pt layer. 

The most prominent nanostructured materials in fuel cells are the electrocatalysts of low- and medium-temperature fuel cells, which consist of carbon-supported precious metal particles in the range of 1-5 nm. This structure is necessary to increase the surface to volume ratio of the noble metals, thus reducing the costs of the material. 

Summarising the activities using nanotechnology for fuel cells, the membrane fuel cell is the most promising type. Thus, the focus of the subsequent chapters will be on this type of fuel cell and will give more details on new approaches using nanostructured electrocatalysts and membranes. 

Ex-situ methods such as diffraction methods show details about the electronic properties of nanostructures [104]. Catalysts made of electronically conducting Ru02 are surrounded by hydrous proton-conducting regions [105], which is necessary for the high activity of this material as a co-catalyst for CO-tolerant Pt-RuO c fuel cell electrocatalysts. 

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. 

Simoes M (2011) Development of multimetallic nanostructured electrocatalysts for an application in a solid alkaline membrane fuel cell (SAMFC). Thesis, Universite de Poitiers, Poitiers... 

Figure 3.2 shows that different kinds of electrocatalysts can give different TOFs (or different catalytic activities) toward an ORR. These nanostructured electrocatalysts include Pt, Pt alloy, and non-noble metal (Fe-based) complexes among which the core—shell structured Pt-based catalyst gives the largest TOF for an ORR. Unfortimately, the structure retention would be the challenge when these core—shell stmctured catalysts are used in fuel cell environments. 

Sarkar A, Murugan AV, Manthiram A. Synthesis and characterization of nanostructured Pd-Mo electrocatalysts for oxygen reduction reaction in fuel cells. 7 Phys Chem C 2008 112(31) 12037-43. 

It is worthwhile to point out that during the last decade, carbon-supported Au Pt core—shell nanostructured catalysts were explored and synthesized to improve the ORR performance of the electrocatalyst. ° The results showed that the limiting... 

Fang, B., Kim, J.H., Yu, J.S. Colloid-imprinted carbon with superb nanostructure as an efBcient cathode electrocatalyst support in proton exchange membrane fuel cell. Electrochem. Commun. 10(4), 659-662 (2008)... 

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