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Kaplan I.M.

Postgraduate student, MIREA – Russian Technological University

FORMATION AND RESEARCH OF BIMETALLIC ELECTRODE MATERIALS ON POLYMER-CARBON CARRIER MATRICES FOR ENERGY POWER SOURCES

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 74-82 p.
Abstract
Fuel cells are promising devices for direct conversion of chemical energy into electrical energy from the point of view of efficiency and low emission of pollutants. The main component of fuel cells is a solid polymer electrolyte. Membranes made of perfluorinated sulfonated copolymers of the Nafion type with different content of sulfogroups satisfy most of the application conditions, because they have a sufficiently high degree of proton conductivity, stability in electrolyte solutions and high mechanical strength. The principal disadvantage of such membranes is their relatively low ion selectivity and a decrease in mechanical strength at temperatures above 100oC. To improve the characteristics of the membrane, various modification methods are used, including various additives and metal nanoparticles. The main obstacle to the widespread large-scale use of fuel cells is their cost, in which the main part is the cost of electrocatalysts based on platinum metals. Therefore, the development of effective electrode materials with a reduced content of platinum metals is an urgent task. In this work, bimetallic platinum-ruthenium nanoparticles were synthesized on combined carrier matrices consisting of a Nafion polymer membrane and carbon nanotubes. The sizes of Pt-Ru nanoparticles were compared with varying the molar ratio of wa-ter:surfactant from 1.5 to 8. It was found that the minimum size is characteristic of nanoparticles obtained with a maximum platinum content in nanoparticles (7:1) and the degree of solubilization ω = 1.5. It was found that in the methanol oxidation reaction, electrode materials based on bimetallic Pt-Ru nanoparticles (7:1) demonstrate the greatest catalytic activity when the catalyst is loaded 0.2 mg/cm2 on polymer substrates with the addition of multi-walled carbon nanotubes at a temperature of 60oC.
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PHYSICO-CHEMICAL FEATURES OF THE PALLADIUM NANOCATALYSTS FORMATION ON COMBINED MATRICES-CARRIER FOR FUEL CELLS

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 58-66 p.
Abstract
The development of modern nanotechnological methods and approaches to the synthesis and formation of nanostructures allows us to create new materials that combine various functional properties and unique physical and chemical characteristics. Such structures include composite materials consisting of a structured matrix modified with various fillers. Currently, composites are of particular interest to researchers, in which nanoscale particles play the role of filler, which makes it possible to obtain catalysts with increased activity and stability. Commercial perfluorinated proton exchange membranes of the Nafion type and carbon-containing carriers (carbon nanotubes, graphene, fullerenes) are promising carrier matrices for chemical energy sources – fuel cells. Nanoparticles based on platinum, palladium, or their alloys are excellent materials for the reactions of electrocatalytic oxidation of hydrogen and oxygen reduction that occur in fuel cells. The elements based on the direct oxidation of formic acid mainly use bimetallic nanoparticles based on palladium, which exhibit higher catalytic properties. In this work, new effective polymer-carbon composites modified with palladium nanoparticles were synthesized. Single- and multi-wall carbon nanotubes were chosen as substrates. Physicochemical studies of the obtained materials were carried out using electron microscopy and small-angle X-ray light scattering. The sizes of nanoparticles in the composition of functional carrier matrices are determined. It was found that the carbon filler contributes to the better stabilization of small nanoparticles in the composition of the composite. The data on the influence of the conditions for the formation of metal nanoparticles on their size, shape and distribution over the matrix surface are obtained. The stability of samples with variable palladium loading on various carrier matrices was studied by chronoamperometry. The prospects of using the formed materials for fuel cell electrodes with direct oxidation of formic acid are proved.
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