Methanol fuel cell catalysts

A key to widespread use of fuel cells as a power source is high-performance, low-cost manufacturable electrocatalyst. Ink-jet technology has been used in library preparation for methanol fuel cell catalysts discovery at Penn State University and Illinois Institute of Technology [34]. 

McLeod EJ, Birss VI. Sol-gel derived WO and WOg/Pt films for direct methanol fuel cell catalyst applications. Electrochim Acta 2005 51 684. 

Li, L. Xing, Y. Pt-Ru nanoparticles supported on carbon nanotubes as methanol fuel-cell catalysts. J. Phys. Chem. cm (2007), pp. 2803-2808. 

Fuel cells can run on fuels other than hydrogen. In the direct methanol fuel cell (DMFC), a dilute methanol solution ( 3%) is fed directly into the anode, and a multistep process causes the liberation of protons and electrons together with conversion to water and carbon dioxide. Because no fuel processor is required, the system is conceptually vei"y attractive. However, the multistep process is understandably less rapid than the simpler hydrogen reaction, and this causes the direct methanol fuel cell stack to produce less power and to need more catalyst. 

This proton exchange membrane is used in both hydrogen and methanol fuel cells, in which a catalyst at the anode produces hydrogen from the methanol. Because the membrane allows the protons, but not the electrons, to travel through it, the protons flow through the porous membrane to the cathode, where they combine with oxygen to form water, while the electrons flow through an external circuit. 

Lasch K, Hayn G, Jdrissen L, Garche J, Besenhardt O (2002) Mixed conducting catalyst support materials for the direct methanol fuel cell. J Power Sources 105 305-310... 

The situation changed drastically in the mid-1990s in view of the considerable advances made in the development of membrane hydrogen-oxygen (air) fuel cells, which could be put to good use for other types of fuel cells. At present, most work in methanol fuel cells utilizes the design and technical principles known from the membrane fuel cells. Both fuel-cell types use Pt-Ru catalyst at the anode and pure platinum catalyst at the cathode. The membranes are of the same type. 

Poisoning of platinum fuel cell catalysts by CO is undoubtedly one of the most severe problems in fuel cell anode catalysis. As shown in Fig. 6.1, CO is a strongly bonded intermediate in methanol (and ethanol) oxidation. It is also a side product in the reformation of hydrocarbons to hydrogen and carbon dioxide, and as such blocks platinum sites for hydrogen oxidation. Not surprisingly, CO electrooxidation is one of the most intensively smdied electrocatalytic reactions, and there is a continued search for CO-tolerant anode materials that are able to either bind CO weakly but still oxidize hydrogen, or that oxidize CO at significantly reduced overpotential. 

Jusys Z, Behm RJ. 2001. Methanol oxidation on a carbon-supported Pt fuel cell catalyst—A kinetic and mechanistic study by differential electrochemical mass spectrometry. J Phys ChemB 105 10874-10883. 

Neergat N, Sbukla AK, Gandhi KS. 2001. Platinum-based alloys as oxygen-reduction catalysts for solid-polymer-electrolyte direct methanol fuel cells. J Appl Electrochem 31 373-378. 

Dinh FIN, Ren X, Garzon FTF, Zelenay P, Gottesfeld S. 2000. Electrocatalysis in direct methanol fuel cells in-situ probing of FTRu anode catalyst surfaces. J Electroanal Chem 491 ... 

Schmidt TJ, Gasteiger HA, Behm RJ. 1999. Methanol electrooxidation on a colloidal PtRu-alloy fuel-cell catalyst. Electrochem Commun 1 1-4. 

The Pt/Ru catalyst is the material of choice for the direct methanol fuel cell (DMFC) (and hydrogen reformate) fuel cell anodes, and its catalytic function needs to be completely understood. In the hrst approximation, as is now widely acknowledged, methanol decomposes on Pt sites of the Pt/Ru surface, producing chemisorbed CO that is transferred via surface motions to the active Pt/Ru sites to become oxidized to CO2... 

Methanol, Formaldehyde, and Formic Acid Adsorption/Oxidation on a Carbon-Supported Pt Nanoparticle Fuel Cell Catalyst A Comparative Quantitative OEMS Study... 

The adsorption and oxidation of the Ci molecules methanol, formaldehyde, and formic acid over a carbon-supported Pt/C fuel cell catalyst under continuous electrolyte flow have been investigated in a quantitative, comparative online DBMS study. 

Coutanceau C, Hahn F, Waszczuk P, Wieckowski A, Lamy C, Leger J-M. 2002. Radioactive labeling study and FTIR measurements of methanol adsorption and oxidation on fuel cell catalysts. Fuel Cells 2 153-158. 

Gao L, Huang H, Korzeniewski C. 2004. The efficiency of methanol conversion to CO2 on thin films of Pt and PtRu fuel cell catalysts. Electrochim Acta 49 1281-1287. 

Jusys Z, Kaiser J, Behm RJ. 2003. Methanol electrooxidation over Pt/C fuel cell catalysts— Dependence of product yields on catalyst loading. Langmuir 19 6759-6769. 

Seiler T, Savinova ER, Eriedrich KA, Slimming U. 2004. Poisoning of PtRu/C catalysts in the anode of a direct methanol fuel cell A OEMS study. Electrochim Acta 49 3927-3936. 

The same group, in a previous work, reported on the realization of a hybrid anode electrode [197]. An appreciable improvement in methanol oxidation activity was observed at the anode in direct methanol fuel cells containing Pt-Ru and Ti02 particles. Such an improvement was ascribed to a synergic effect of the two components (photocatalyst and metal catalyst). A similar behavior was also reported for a Pt-Ti02-based electrode [198]. Another recent study involved the electrolysis of aqueous solutions of alcohols performed on a Ti02 nanotube-based anode under solar irradiation [199]. 

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