Catalysts for oxygen reduction

Lead Telluride. Lead teUuride [1314-91 -6] PbTe, forms white cubic crystals, mol wt 334.79, sp gr 8.16, and has a hardness of 3 on the Mohs scale. It is very slightly soluble in water, melts at 917°C, and is prepared by melting lead and tellurium together. Lead teUuride has semiconductive and photoconductive properties. It is used in pyrometry, in heat-sensing instmments such as bolometers and infrared spectroscopes (see Infrared technology AND RAMAN SPECTROSCOPY), and in thermoelectric elements to convert heat directly to electricity (33,34,83). Lead teUuride is also used in catalysts for oxygen reduction in fuel ceUs (qv) (84), as cathodes in primary batteries with lithium anodes (85), in electrical contacts for vacuum switches (86), in lead-ion selective electrodes (87), in tunable lasers (qv) (88), and in thermistors (89). 

Trapp V, Christensen PA, Hamnett A (1996) New catalysts for oxygen reduction based on transition-metal sulfides. J Chem Soc Earaday Trans 92 4311 319... 

Bron M, Bogdanoff P, Fiechter S, Hilgendorff M, Radnik J, Dorbandt I, Schulenburg H, Tributsch HJ (2001) Carbon supported catalysts for oxygen reduction in acidic media prepared by thermolysis of Ru3(CO)i2. Electroanal Chem 517 85-94... 

Christenn C, Steinhilber G, Schulze M, Friedrich KA (2007) Physical and electrochemical characterization of catalysts for oxygen reduction in fuel cells. J Appl Electrochem 37 1463-1474... 

Suo YG, Zhuang L, Lu JT. 2007. Pirst-principles considerations in the design of Pd-altoy catalysts for oxygen reduction. Angew Chem Int Ed 46 2862-2864. 

Fuel cell applications Manganese dioxide as a new cathode catalyst in microbial fuel cells [118] OMS-2 catalysts in proton exchange membrane fuel cell applications [119] An improved cathode for alkaline fuel cells [120] Nanostructured manganese oxide as a cathodic catalyst for enhanced oxygen reduction in a microbial fuel cell [121] Carbon-supported tetragonal MnOOH catalysts for oxygen reduction reaction in alkaline media [122]... 

Sun, W., Hsu, A. and Chen, R. (2011) Carbon-supported tetragonal MnOOH catalysts for oxygen reduction reaction in alkaline media. Journal of Power Sources, 196, 627-635. 

Platinum is one of the best - and most expensive - catalyst for oxygen reduction. The following reaction scheme is fairly well established ... 

Catalysts for Oxygen Reduction (Cathodes) At the cathode, the reduction of oxygen requires higher amounts of platinum. Figure 14.10, showing the individual... 

There has long been interest in investigating Fe- and Co-based catalysts for oxygen reduction because of their role as highly effective enzymes for oxygen transport and conversion in biological systems. More recently, additional interest has been centered on alternative precious metals, metal oxides, and metal carbides and nitrides as possible oxygen reduction catalysts. 

There is increased interest in the use of Ru-based systems as catalysts for oxygen reduction in acidic media, because these systems have potential applications in practicable direct methanol fuel cell systems. The thermolysis of Ru3(CO)i2 has been studied to tailor the preparation of such materials [123-125]. The decarbon-ylation of carbon-supported catalysts prepared from Ru3(CO)i2 and W(CO)6, Mo(CO)is or Rh(CO)is in the presence of selenium has allowed the preparation of catalysts with enhanced activity towards oxygen reduction, when compared with the monometallic ruthenium-based catalyst [126],... 

Further, Pt-based binary catalysts, such as Pt/Cr and Pt/Ni [18], are less sensitive to the presence of alcohol than pure Pt, giving hope for the development of better catalysts for oxygen reduction. 

Cobalt porphyrins have been some of the most studied catalysts for oxygen reduction, due in part to their strong interaction with molecular oxygen and the ease with which they catalyze the reduction at low potentials. Anson and coworkers [97] performed a study of the simplest of cobalt porphyrins, cobalt porphine, in the hope of gaining a baseline for the observed reactions of other porphyrins. Instead, they observed a very different process from most other monomeric cobalt porphyrins. 

Earlier, such catalyst was used for the preparation of a 100 W rechargeable bipolar zinc-oxygen battery [328]. Also, nanostructured Mn02 combined with mesocarbon microbeads was prepared and used [329] in such batteries as a catalyst for oxygen reduction, which has a very good electrocatalytic activity with respect to oxygen, and in comparison with electrolytic Mn02. Prepared with this material, the all solid-state zinc-air cell... 

TABLE 3. Perspective non-precious metal catalysts for oxygen reduction... 

The catalysts for oxygen reduction and oxygen oxidation are materials based on substances like Co, Ni, Fe, Mn [16, 19]. One of new applications of oxygen reduction catalysts is air-metal hydride accumulator. Electrodes based on La0.1Cao.4Co03, La0. Cao.,jMn03 [18] are used in this battery. The electrodes of similar composition could be used in SOFC. An insertion of the oxides in their composition (CuO for example) leads to increasing the conductivity of system and efficiency of catalyst [30]. 

ELECTROCONDUCTIVE POLYMERS AND EXFOLIATED GRAPHITE COMPOSITES AS CATALYSTS FOR OXYGEN REDUCTION... 

Bezerra C, Zhang L, Liu H, Lee K, Marques A, Marques E, Wang H, Zhang J, (2007). A review of heat-treatment effects on activity and stability of PEM fuel cell catalysts for oxygen reduction reaction Journal of Power Sources 173 891-908 Blesl M, Fahl U, Ohl M, (2004). HochtemperaturbrennstofFzellen und deren Kostenentwicklung. BWK, 56 72-56... 

Wang, B., Recent development of non-platinum catalysts for oxygen reduction reaction, J. Power Sources, 152, 1, 2005. 

Villers, D., Jacques-Bedard, X., and Dodelet, J.-R, Fe-based catalysts for oxygen reduction in PEM fuel cells, J. Electrochem. Soc., 151, A1507, 2004. 

Okada, T. et al., A comparative study of organic cobalt complex catalysts for oxygen reduction in polymer electrolyte fuel cells, J. Inorg. Organometal. Polym., 9,199,1999. Bron, M. et al., EXAFS, XPS and electrochemical studies on oxygen reduction catalysts obtained by heat treatment of iron phenanthroline complexes supported on high surface area carbon black, J. Electroanal. Chem., 535, 113, 2002. 

As in the case of catalysts for oxygen reduction, the surface properties of Pt catalysts for methanol oxidation are governed by both the preparation method and the nature of carbon support. As discussed above, the presence of surface groups such as carboxylic, carbonyl, phenolic, lactone, and pyrone functionalities determine... 

Besides the effects of the typical carbon functional groups, the role of nitrogen and sulfur functionalities, introduced on carbons by chemical and thermal treatments, on the electrochemical performance of Pt catalysts for oxygen reduction in direct methanol fuel cells was investigated [47]. Once again, the metal-support interaction influences the size and chemical state of platinum particles and, as a consequence, the electrocatalytic activity. The introduction of nitrogen and sulphur functionalities was reported to improve the catalytic activity, but this result was mainly ascribed to the Pt particle size. 

Several molecules were investigated because of the applicability in a system of interest. Silver oxide was investigated by Kotz and Yeager" for the significance of the silver/silver oxide electrode as a cathode in batteries and as a catalyst for oxygen reduction. Mercaptobenzothiazole was studied" " for its role as a corrosion inhibitor for several metals. Von Raben et could follow... 

IV.D.IO Low-Platinum Catalysts for Oxygen Reduction at PEMFC Cathodes... 

Gorlin Y, Jamarillo TF (2010) A bifunctional nonprecious metal catalyst for oxygen reduction and water oxidation. J Am Chem Soc 132 13612-13614... 

The cathodic reaction of a MFC is an electron consumption or reduction process (Figure 5.2). For a typical air cathode MFC, Pt is usually used as the catalyst for oxygen reduction. Under Pt catalysis, the electrons from the anode and protons transported from the anodic compartment will reduce the oxygen, which is accompanied by water generation. The chemical reaction occurring on the air cathode is O2 + + e H2O (Figure 5.2). Recently,... 

Lalande, G., R. Cote, D. Guay, J.P. Dodelet, L.T. Weng, and P. Bertrand (1997). Is nitrogen important in the formulation of Fe-based catalysts for oxygen reduction in solid polymer fuel-cells Electrochim. Acta 42,1378-1388. 

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