Energy and energy-saving | A.N. Frumkin Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences

New Catalysts for Fuel Cells with Direct Ethanol Oxidation and Membrane-Electrode Assemblies on the Basis of them

28 апреля, 2011

Fuel cells (FC) with direct ethanol oxidation are promising power sources for transport and portative devices. Usage of ethanol is hampered the problems with preparation, storage and supply of fuel and also provides close ecologically clean cycle of energy transformation in nature scale.

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In “Electrocatalysis and Fuel Cells” laboratory, effective multicomponent nanosized catalysts on the different carbon supports have been developed. They are synthesized for FC cathodes and anodes as on the basis of platinum (PtМ1 M2/С, where М1 = Sn, Ru; M2 = Co, Ni, Mo, V) and without platinum (Pd, Ru-МОx/С (М= V, Ni, Cr); CoTMPP/С). Morphology of synthesized catalysts was studied by physicochemical methods (TEM, XDA, XPS). Kinetics and mechanism of current-forming reactions on these catalysts were investigated in model conditions in acid and alkaline solutions with complex of electrochemical methods (RDE, RRDE, CVA). The estimation of depth of ethanol oxidation was performed by gas and liquid chromatography methods. It was shown that depth of ethanol oxidation in acid medium on multicomponent systems is 40% and achieves 60% in alkaline medium.

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Life-cycle tests of FC with acid electrolyte. U=0.5 V.

Anode: PtSn/С. Cathode: Pt/С. 1М С2Н5ОН, O2, 750С.

For formation of membrane-electrode assemblies on the basis of suggested catalysts, the methods low-production output of MEA’s were developed. These MEA’s with active surface area up to 225 сm2 were produced with screen process printing at automated equipment EKRA. The testing of FC prototype model is performed on specialized equipment of world level, Arbin and ElectroChem test setup.

Head of  the Laboratory of Electroсatalysis and Fuel Cells, professor, Doctor of Science (Chemistry) Mikhail Romanovich Tarasevich


Three-Metallic Nanosized Systems for Cathodes of Fuel Cells and Membrane-Electrode Assemblies on the Basis of them

28 апреля, 2011

Widespread development and commercialization of fuel cells require considerable lowering the amount used platinum in cathodic catalysts. One of the ways of such a lowering consists in usage of bi- and three-metallic systems instead monoplatinum catalysts.

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Parameters of membrane-electrode assemblies for monoplatinum catalyst and two three-metallic systems demonstrated the possibility of lowering the amount used platinum

The usage of bi- and three-metallic systems, moreover, gives rise to significant increase of cathodic catalyst stability. It can be connected with the formation of core-shell structures as in the process  of chemical pretreatment of catalysts and their electrochemical potential cycling.

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Discharge parameters of hydrogen-air fuel cell with 20PdCo5Pt cathodic catalyst at the different loading of metallic phase (m.ph.). Membrane Nafion 212, 65ºС, gas pressure 1 atm. Anode: 20Pt/С (HiSPEC) 0.2 mg m.ph./сm2.

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Microphotographs of 30PtCoCr/С (a) and 20PdCo5Pt (b) catalysts and their histograms.


Head of  the Laboratory of Electroсatalysis and Fuel Cells, professor, Doctor of Science (Chemistry) Mikhail Romanovich Tarasevich


Non-Containing Precious Metals Cathodic Catalysts for Proton Exchange Membrane Fuel Cells and Membrane-Electrode Assemblies on the Basis of them

28 апреля, 2011

The high cost and scarcity of platinum which just now is the most active cathodic catalyst for low-temperature fuel cells with proton exchange membrane induce all over the world the constant search and development of nonplatinum active and stable enough catalysts.

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The parameters of H2-O2 5 cm2 square fuel cell. Membrane: Nafion 212. Cathode: X/С 4.0 mg cat./ cm2. Anode: Pt/C (E-TEK) 0.2 mg Pt/cm2. Gas humidity: 95%. MEA’s testing were performed with ElectroChem. test setup.

The Figure on the left presents the results of search of such a catalyst tested in hydrogen-oxygen fuel cell. Discharge curve shows that the value of current density at E=0.6 V achieves 0.4 A/cm2. The dependence of specific power on current density shows the maximum at 350 mW/cm2.

In the laboratory it was shown that platinum-like dependence of kinetic parameters of oxygen reduction reaction on pH is the most important test program for the evaluation of cathodic catalysts. From the Figure represented below it follows that the behaviour of E1/2-pH dependence for a new catalyst (conditionally denote here as Х/С) is identical to the dependence for platinum that speaks about prospectivity of the new system. Meanwhile for carbon material, E1/2 independence of pH practically takes place. Moreover, XPS on initial catalyst (а) and after its treatment in sulfuric acid during 50 h (b) show high enough stability of the new catalytic system.

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pH dependence of half-wave potential for oxygen reduction reaction

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XPS for N 1s of X/C initial system (a) and after the treatment in sulfuric acid during 50 h

Head of  the Laboratory of Electroсatalysis and Fuel Cells, professor, Doctor of Science (Chemistry) Mikhail Romanovich Tarasevich


The principles of a superhydrophobicnanocomposite coatings

22 октября, 2009

The principles of a superhydrophobicnanocomposite coatings by depositing nanoparticles dispersions have been developed on the basis of theoretical analysis of the forces that determine the aggregation in the bulk of multi-component dispersions and in wetting films of the dispersions. The perspective projection of obtaining surface texture necessary for  achieving of superhydrophobic states on the basis of directed aggregation of nanoparticles have been shown, which have not been previously possible. As it has been established dispersions with non-polar or weakly polar media and uncharged nanoparticles are the most appropriate for obtaining superhydrophobicnanocomposite coatings.

Head of the Laboratory of Surface Forces, Dr. Sc.Alexander M. Emelianenko, principal researcher, Associated member of the RAS Lyudmila B. Boynovich


 
 
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