Direct methanol fuel cell anode catalyst

Steigerwalt, S.E. et al., A Pt-Ru/graphitic carbon nanofiber nanocomposite exhibiting high relative performance as a direct-methanol fuel cell anode catalyst, J. Phys. Chem. B., 105, 8097, 2001. 

R. X. Liu, and E. S. Smotkin, Array membrane electrode assemblies for high throughput screening of direct methanol fuel cell anode catalysts, J. Electroanal. Chem. 535, 49-55 (2002). 

R. Liu and E. Smotkin, Array Membrane Electrode Assemblies for High Throughput Screening of Direct Methanol Fuel Cell Anode Catalysts, J. Electroanal. Chem., 535, 49 (2002). 

Ferrin P, Nilekar AU, Greeley J, Mavrikakis M, Rossmeisl J (2008) Reactivity descriptors for direct methanol fuel cell anode catalysts. Surf Sci 602 3424—3431... 

Lukehart and coworkers [26] successfully prepared a Pt-Ru/graphitic carbon nanofiber nanocomposite exhibiting high relative performance as a direct methanol fuel cell anode catalyst Multistep deposition and reactive decomposition of a single-soiuce molecular precursor of Pt and Ru metal on herringbone graphitic carbon nanofibers affords a Pt-Ru/GNF nanocomposite containing Pt-Ru alloy nanoclusters widely dispersed on the GNF support The nanocomposite has a total metal content of 42 wt% with a bulk Pt/Ru atomic ratio of about 1 1 and... 

Recent work by Lukehart et al. has demonstrated the applicability of this technique to fuel-cell catalyst preparation [44g,h]. Through the use of microwave heating of an organometallic precursor that contains both Pt and Ru, PtRu/Vulcan carbon nanocomposites have been prepared that consist of PtRu alloy nanoparticles highly dispersed on a powdered carbon support [44g]. Two types of these nanocomposites containing 16 and 50 wt.% metal with alloy nanoparticles of 3.4 and 5.4 nm, respectively, are formed with only 100 or 300 s of microwave heating time. The 50 wt.% supported nanocomposite has demonstrated direct methanol fuel-cell anode activity superior to that of a 60 wt.% commercial catalyst in preliminary measurements. 

Figure 12.9. Schematic drawing of an assembled electrochemical cell for combinatorial screening catalyst libraries prepared by sputter deposition [22], (Reprinted from Joiunal of Power Sources, 163(1), Cooper JS, McGinn PJ. Combinatorial screening of thin film electrocatalysts for a direct methanol fuel cell anode, 330-8, 32006, with permission from Elsevier.)...

Platinum Alloy Catalysts for Direct Methanol Fuel Cell Anodes... 

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. 

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 ... 

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... 

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]. 

This survey focuses on recent developments in catalysts for phosphoric acid fuel cells (PAFC), proton-exchange membrane fuel cells (PEMFC), and the direct methanol fuel cell (DMFC). In PAFC, operating at 160-220°C, orthophosphoric acid is used as the electrolyte, the anode catalyst is Pt and the cathode can be a bimetallic system like Pt/Cr/Co. For this purpose, a bimetallic colloidal precursor of the composition Pt50Co30Cr20 (size 3.8 nm) was prepared by the co-reduction of the corresponding metal salts [184-186], From XRD analysis, the bimetallic particles were found alloyed in an ordered fct-structure. The elecbocatalytic performance in a standard half-cell was compared with an industrial standard catalyst (bimetallic crystallites of 5.7 nm size) manufactured by co-precipitation and subsequent annealing to 900°C. The advantage of the bimetallic colloid catalysts lies in its improved durability, which is essential for PAFC applicabons. After 22 h it was found that the potential had decayed by less than 10 mV [187],... 

Mu, Y., et al., Controllable Ptnanoparticle deposition on carbon nanotubes as an anode catalyst for direct methanol fuel cells. The Journal of Physical Chemistry B, 2005.109(47) ... 

In electrochemical systems, metal meshes have been widely used as the backing layers for catalyst layers (or electrodes) [26-29] and as separators [30]. In fuel cells where an aqueous electrolyte is employed, metal screens or sheets have been used as the diffusion layers with catalyst layers coated on them [31]. In direct liquid fuel cells, such as the direct methanol fuel cell (DMFC), there has been research with metal meshes as DLs in order to replace the typical CFPs and CCs because they are considered unsuitable for the transport and release of carbon dioxide gas from the anode side of the cell [32]. 

Cao, D., Bergens, S.H. 2004. Pt-Ru j , nanoparticles as anode catalysts for direct methanol fuel cells. J Power Sources 134 170-180. 

Most of the catalysts employed in PEM and direct methanol fuel cells, DMFCs, are based on Pt, as discussed above. However, when used as cathode catalysts in DMFCs, Pt containing catalysts can become poisoned by methanol that crosses over from the anode. Thus, considerable effort has been invested in the search for both methanol resistant membranes and cathode catalysts that are tolerant to methanol. Two classes of catalysts have been shown to exhibit oxygen reduction catalysis and methanol resistance, ruthenium chalcogen based catalysts " " and metal macrocycle complexes, such as porphyrins or phthalocyanines. ... 

In a fuel cell, inductance is usually caused by the adsorbed species on the electrode surface. For example, in a direct methanol fuel cell, adsorption of CO on the anode catalyst can at low frequencies result in an inductance loop. 

Havranek A, Wippermann K (2004) Determination of proton conductivity in anode catalyst layers of the direct methanol fuel cell (DMFC). J Electroanal Chem 567(2) 305-15... 

Reddington et al. (66) reported the synthesis and screening of a 645-member discrete materials library L9 as a source of catalysts for the anode catalysis of direct methanol fuel cells (DMFCs), with the relevant goal of improving their properties as fuel cells for vehicles and other applications. The anode oxidation in DMFCs is reported in equation 1 (Fig. 11.12). At the time of the publication, state-of-the-art anode catalysts were either binary Pt-Ru alloys (67) or ternary Pt-Ru-Os alloys (68). A systematic exploration of ternary or higher order alloys as anode catalysts for DMFCs was not available, and predictive models to orient the efforts were also lacking. 

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