Direct Methanol Oxidation

Gottesfeld, S., and T. A. Zawodzinski, Direct methanol oxidation fuel cells from a 20th century electrochemist s dream to a 21st century emerging technology, in Electrochemical Science and Engineering, R. C. AUdre et al., Eds., Vol. 5, WUey, New York, 1988. 

Figure 12. Cyclic voltammograms of direct methanol oxidation catalyzed by the porous Pt nanoparticle membrane and as-made Pt nanoparticles. The reaction solution was made of an aqueous mixture containing O.IMHCIO4 and 0.125 M methanol. (Reprinted with permission from Ref [31], 2005, Wiley-VCH.)...

The direct path, which seems the direct methanol oxidation route to CO2 without /toCOad as an intermediate, was confirmed as well as a path involving AoCOad- eoCOad laay be one of the active intermediates of the direct path. Although methanol oxidation probably consists of more complex reactions, it is convenient and useful to treat it in terms of these two parallel reactions the direct path and the CO path. 

Direct methanol oxidation is a candidate for the anodic fuel to run electric surface transportation (Chapter 13). Thus, MeOH would provide a liquid fuel and use of much of the present infrastructure. Here, with a large financial investment at stake in the... 

FIGURE 4.3 Research and development issues in the development of direct methanol oxidation fuel cells. 

Thus, a predominantly new means of formaldehyde production by direct methanol oxidation with hydrogen peroxide under homogeneous conditions without methanol formation stage was suggested. 

Platinum, ruthenium and PtRu alloy nanoparticles, prepared by vacuum pyrolysis using Pt(acac)2 and Ru(acac)3 as precursors, were applied as anode catalysts for direct methanol oxidation . The nanoparticles, uniformly dispersed on multiwaUed carbon nanotubes, were all less than 3.0 nm in size and had a very narrow size distribution. The nanocomposite catalysts showed strong electrocatalytic activity for methanol oxidation, which can... 

As mentioned above, direct methanol oxidation and reformate tolerance represent two very challenging but significantly different electrocatalytic issues. This is despite the fact that poisoning by CO (or similar Ci moieties) is one of the critical aspects for both fuels. Binary catalysts such as PtSn, PtMo or PtRu offer superior performance but the precise reason for this is not known. At least 3 different mechanisms have been proposed, whereby the alloying M element ... 

The improvements in the activation polarization defined as either mass-specific activity or site-specific activity (activity/number of specific crystal planes on the surface) were reported, especially for the kinetically difficult ORR. Wealth of prior data on both ORR as well as direct methanol oxidation (both multielectron reduction and oxidation processes) showed clear particle-size effects. Bulk of these... 

Case Study 1 Pt/Ru Carbon Three types of 30 wt.% PtsoRuso/Vulcan XC 72 electrocatalysts for Direct Methanol Oxidation Fuel Cells (DMFC) were prepared using Nl BetsH (Cat. 1), LiBetsH (Cat 2.), and Al(Me)3 (Cat 3.) for the co-reduction of Pt- and Ru-salts [169] ... 

Long JW, Stroud RM, Swider-Lyons KE, Rolison DR (2000) How to make electrocatalysts more active for direct methanol oxidation—avoid PtRu bimetallic alloys J Phys Chem B 104 9772-9776... 

CV and the MSCV for CO2 during the stripping of COad from Pt(pc)- and Mo-modified Pt surface [38]. The presence of Mo shifts the onset of CO2 formation by about 200 mV to lower potentials (0.2 V), although the oxidation of the largest part of CO remains tmaffected. This early oxidation of the so-called weakly adsorbed CO (which is masked in the CV by the surface oxidation of Mo itselO results in a sufficient number of free surface sites for the oxidation of H2, which in case of the PEM fuel cell frequently contains some residual CO. No positive effect for direct methanol oxidation is observed. However, when Ru-modified surfaces are used, the main oxidation peak for CO oxidation is shifted downwards, which, together with the faster adsorption of methanol to form COad, results in a preferential oxidation of methanol in the reaction path via COad, yielding higher current efficiencies even at smooth electrodes [39-41]. 

Entropy change in the direct methanol oxidation (J mol K ) Variation of overpotential across the catalyst layer (V) (2.127) Dimensionless parameter (2.13) and (4.157)... 

A survey XPS scan on a material can provide a qualitative analysis of the elemental eomposition on the surface. The XPS survey scan spectra of Pt/MWCNT nanocomposites before and after reduction treatment are shown in Figure 10.15(e). Elements of Pt, Cl, C, and O existed in flie Pt/MWCNT nanocomposite before the reduetion treatment. However, the Cl 2p peak vanished after the reduction, indicating removal of chloride ions in the reduced sample. The removal of halide ion impurities sueh as Cf ean improve the activities of the catalyst for CO oxidation and also direct methanol oxidation reactions in fuel cells [136,137]. 

Watanabe M, Saegusa S, Stonehart P. High platinum electrocatalyst utilizations for direct methanol oxidation. J Electroanal Chem 1989 271 213-20. 

Long, J.W., Stroud, R.M., Swider-Lyons, K.E. Rolison, R. How to make electrocatalysts more active for direct methanol oxidation-avoid PtRu bimetallic alloys. J. Phys. Chem. B 104 (2000), pp. 9772 9776. 

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