Electrocatalysts for oxygen

Several activities, if successful, would strongly boost the prospects for fuel ceU technology. These include the development of (/) an active electrocatalyst for the direct electrochemical oxidation of methanol (2) improved electrocatalysts for oxygen reduction and (2) a more CO-tolerant electrocatalyst for hydrogen. A comprehensive assessment of the research needs for advancing fuel ceU technologies, conducted in the 1980s, is available (22). 

In acid electrolytes, carbon is a poor electrocatalyst for oxygen evolution at potentials where carbon corrosion occurs. However, in alkaline electrolytes carbon is sufficiently electrocatalytically active for oxygen evolution to occur simultaneously with carbon corrosion at potentials corresponding to charge conditions for a bifunctional air electrode in metal/air batteries. In this situation, oxygen evolution is the dominant anodic reaction, thus complicating the measurement of carbon corrosion. Ross and co-workers [30] developed experimental techniques to overcome this difficulty. Their results with acetylene black in 30 wt% KOH showed that substantial amounts of CO in addition to C02 (carbonate species) and 02, are... 

Lee JW, Popov BN (2007) Ruthenium-based electrocatalysts for oxygen reduction reaction—a review. J Solid State Electrochem 11 1355-1364... 

Lee K, Zhang L, Zhang J (2007) Ternary non-noble mefal chalcogenide (W-Co-Se) as electrocatalyst for oxygen reduction reaction. Electrochem Commun 9 1704-1708... 

Guild AF, Gancs L, Allen RJ, Mukerjee S (2007) Carbon-supported low-loading rhodium sulfide electrocatalysts for oxygen depolarized cathode applications. Appl Catal A 326 227-235... 

Stamenkovic V, Mun BS, Mayrhofer KJJ, Ross PN, Markovic NM, Rossmeisl J, Greeley J, Nprskov JK. 2006. Changing the activity of electrocatalysts for oxygen reduction by tuning the surface electronic structure. Angew Chem Int Ed 45 2897. 

Sasaki K, Zhang L, Adzic RR. 2008. Niobium oxide-supported platinum ultra-low amount electrocatalysts for oxygen reduction. Phys Chem Chem Phys 10 159-167. 

Shao MH, Huang T, Liu P, Zhang J, Sasaki K, Vukmirovic MB, Adzic RR. 2006a. Palladium monolayer and palladium alloy electrocatalysts for oxygen reduction. Langmuir 22 10409-10415. 

Shao MH, Sasaki K, Adzic RR. 2006c. Pd-Fe nanoparticles as electrocatalysts for oxygen reduction. J Am Chem Soc 128 3526-3527. 

Zhang J, Vukmirovic MB, Xu Y, Mavrikakis M, Adzic RR. 2005a. Controlling the catalytic activity of platinum-monolayer electrocatalysts for oxygen reduction with different substrates. Angew Chem Int Ed 44 2132-2135. 

Lalande G, Cote R, Tamizhmani G, Guay D, Dodelet JP. 1995. Physical, chemical and electrochemical characterization of heat-treated tetracarboxylic cobalt phthalocyanine adsorbed on carbon black as electrocatalyst for oxygen reduction in polymer electrolyte fuel cells. Electrochim Acta 40 2635-2646. 

Yang H, Alonso-Vante N, Leger JM, Lamy C. 2004. Tailoring, structure, and activity of carbon-supported nanosized Pt-Cr alloy electrocatalysts for oxygen reduction in pure and methanol-containing electrolytes. J Phys Chem 108 1938-1947. 

Khorasani-Motlagh M, Noroozifar M, Ghaemi A, Safari N. 2004. Iron(III) octaethylporphyrin chloride supported on glassy carbon as an electrocatalyst for oxygen reduction. J Electroanal Chem 565 115. 

The organometallic complexes with d-metals are considered as promising electrocatalysts for oxygen electroreduction in air-metal electrochemical cells. Obviously, the first idea was to employ the catalytic mechanism of the oxygen reduction with porphyrin-like metal complexes [1] found in living beings (Figure 1). 

The electrocatalysts for oxygen reduction were prepared as follows. These complex compounds were inoculated onto the carbon (AG-3, BET area near 800 m2/g) by means of adsorption from dimethylformamide solutions. The portion of complex compound weighed so as to achieve 3% of Co content was mixed with the carbon, then 5 ml of dimethylformamide per 1 g of the carbon were added and the mixture was cured at room temperature for 24 hours. Series of samples obtained were thermally treated (pyrolyzed), and the resulting grafted carbons were tested as electrode materials in the reaction of molecular oxygen reduction. 

Balei J., Electrocatalysts for oxygen evolution in advanced water electrolysis, Int. J. Hydrogen Energ., 10(2), 89-99,1985. 

J. Liang, Y. Jiao, M. Jaroniec, S. Z. Qiao, Sulfur and nitrogen dual-doped mesoporous graphene electrocatalyst for oxygen reduction with synergistically enhanced performance, Angew. Chem. Int. Ed., vol. 51, pp. 1-6, 2012. 

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). 

Another prospect for eflBcient energy conversion is the fuel cell. The diflFerent types of fuel cells presently under study or development were reviewed by G. Belanger of Hydro-Quebec, who concluded that commercial availability of such units is now in sight. However, the need to develop cheap, efficient electrocatalysts for oxygen reduction remains. 

Transition metal compounds, such as organic macrocycles, are known to be good electrocatalysts for oxygen reduction. Furthermore, they are inactive for alcohol oxidation. Different phthalocyanines and porphyrins of iron and cobalt were thus dispersed in an electron-conducting polymer (polyaniline, polypyrrole) acting as a conducting matrix, either in the form of a tetrasulfonated counter anion or linked to... 

Rashkova, V. Kitova, S. Konstantinov, I. Vitanov, T. Vacuum evaporated thin films of mixed cobalt and nickel oxides as electrocatalyst for oxygen evolution and reduction. Electrochimica Acta (2002) 47(10) 1555-1560. 

The application of gold as an electrocatalytic component within the fuel cell itself has to date been limited primarily to the historical use of a gold-platinum electrocatalyst for oxygen reduction in the Space Shuttle/Orbiter alkaline fuel cells (AFC)88 and the recent use of gold for borohydride oxidation in the direct borohydride alkaline fuel cell (DBAFC).89,90 Electrocatalysts with lower cost, improved carbon monoxide tolerance and higher... 

Previously, the first reviews on alloy electrocatalysts for oxygen reduction in phosphoric acid fuel-cells44"46 concentrated on those patents that had been issued in the United States, since that was where most of the early work had been done. Subsequendy, similar alloy work has been done in Japan, and that work is reflected in the Japanese patent literature shown in Table 3, whence corresponding alloy-combination atom ratios and the air/oxygen performance values are given in Table 3a. 

A number of other oxides have been investigated as electrocatalysts for oxygen evolution, e.g. lead dioxide, manganese dioxide, and nickel oxide. 

Bouwman, P.J. et al., Platinum-iron phosphate electrocatalysts for oxygen reduction in PEMFCs, J. Electrochem. Soc., 151, A1989, 2004. 

Gojkovic, S.L., Gupta, S., and Savinell, R.F., Heat-treated iron(lll) tetramethoxyphe-nyl porphyrin chloride supported on high-area carbon as an electrocatalyst for oxygen reduction, Electrochim. Acta, 45, 889, 1999. 

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