Methanol electro-oxidation PtRu catalyst

It can also be observed from this figure that Sn-containing catalyst is a more effective catalyst for the oxidation of CO than that containing Ru, as a lower onset potential of the oxidation wave is obtained with the former catalyst. It has also to be noted that PtSn catalysts are less active towards methanol electrooxidation than PtRu catalysts (see Section IV. 1). ° However, adsorbed CO species are proposed as reaction intermediates of methanol electro-oxidation, which seems to lead to a paradoxical behavior of PtSn based catalysts. In CO stripping experiments, a negative shift of the onset potential for the oxidation of adsorbed CO on PtSn also occurs. " On the basis of in situ infrared spectroscopy studies coupled with electrochemical measurements, Mo-... 

Lizcano-Valbuean WH, Paganin VA, Gonzalez ER. Methanol electro-oxidation on gas diffusion electrodes prepared with PtRu/C catalysts. Electrochim Acta 2002 47 3715-22. 

Lach K, Jorissen L, Friedrich KA, Garche J. The function of ruthenium oxides in PtRu catalysts for methanol electro-oxidation at low temperatures. J Solid State Electrochem 2003 7 619-25. 

Ma, L., Liu, C., Liao, X, Lu,T.,Xing, W. Zhang, X High activity PtRu/C catalysts synthesized by amodified impregnation method for methanol electro-oxidation. Electrochim. Acta 54 (2009), pp. 7274-7279. 

MWNT and high surface area mesoporous carbon xerogel were prepared and used as supports for mono-metallic Pt and bi-metaUic PtRu catalysts by J.L. Figueiredo [32]. A remarkable increase in the activity was observed when PtRu catalysts were supported on the oxidized xerogel. From the XPS results, it had been shown that the oxidized support helps to maintain the metals in the metalUc state, as required for the electro-oxidation of methanol. 

Several approaches have been considered to optimize the electrochemical behaviour of bimetallic catalysts. For example, some authors have studied the effect of PtRu catalyst structure on methanol and CO electro-oxidation, " whereas other authors " have focused on the optimal Pt/Ru atomic ratio. 

Dubau, L., Hahn, F., Coutanceau, C., et al. (2003). On the Structure Effects of Bimetallic PtRu Electrocatalysts Towards Methanol Oxidation, J. Electroanal. Chem., 554-555, pp. 407-415. Vigier, F., Coutanceau C., Hahn, R, etal. (2004), On the Mechanism of Ethanol Electro-oxidation on Pt and PtSn Catalysts Electrochemical and In Situ IR Reflectance Spectroscopy Studies,... 

Gupta et al. (2004) studied the cyclic voltammograms (Fig. 10) of ethanol electro-oxidation behavior on CuNi, CuNi/Pt and CuNi/PtRu alloys electro-catalysts in 0.5 M NaOH solution. Fig. 10 (a) shows a steady rise of the anodic peak current for the CuNi/Pt electro-catalyst. The peak current increases substantially from F to the 50 scan. Fig. 10 (b) shows the increase in reaction kinetics for ethanol electro-oxidation when Ru is added in the alloy. They have detected the presence of acetaldehyde and CO2 (as carbonate) with CuNi/PtRu electro-catalyst Authors found carbonate ions because of the cleavage of C—C bond of ethanol molecule. The temperature of ethanol electro-oxidation was not mentioned although the experimental work was done at room temperature. Tripkovic et al. (2001) studied the electro-oxidation of methanol, ethanol, -propanol and n-butanol (C[—C4 alcohol) in alkaline solution at the Pt (111) and vicinal stepped planes Pt (755) and Pt (332). The nature of the oxygen-containing species as well as their role in the alcohol oxidation is proposed. A dual path reaction mechanism as shown by eqs. (4) and (5) is proposed based on the assumptions that RCOa is a reactive intermediate of the main reaction path, while CO2 is a product of the poisoning species oxidation in a parallel reaction path. 

To enhance the mass activity of Pt, the modification of the catalytic platinum surface by the addition of a second or multiple metals has been developed to remarkably reduce Pt loading while enhancing the catalytic performance. For CO and methanol oxidation reactions, while PtRu is the practical electro-catalyst, PtMo (core-shell) and other ternary catalysts show very high activity in the oxidation of CO and/or methanol. Well-defined Pt3Ni surfaces and Pt3(CoNi) are two good examples to show how judicious design can be beneficial to dramatically enhanced activity in catalyzing ORRs. 

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