Abstract
Ti0.8M0.2O2-C composites are novel supports for Pt-based fuel cell electrocatalysts with enhanced stability and CO-tolerance. In this work the effect of the type of the carbonaceous material (Vulcan XC-72, Black Pearls 2000 and graphite oxide) as well as the mixed oxide/carbon ratio was explored on the structure and the electrochemical performance of the supports and the related electrocatalysts. The composites were prepared by optimized routes tailored to the special features of the carbonaceous materials.Better CO tolerance was obtained on the catalysts containing 75 wt.% of the Ti0.8Mo0.2O2 as compared to those with high carbon content. However, the more homogeneous microstructure of the catalysts with high carbon content (75 wt.%) was identified as the key for enhanced long-term stability. Considering also the fact that the high oxide content of the catalyst increases the cell resistance, the Black Pearls-based Pt electrocatalysts with Ti0.8Mo0.2O2/C = 25/75 ratio seem to be the most promising.
Highlights
Fuel cells convert chemical energy of hydrogen-rich fuels into elec tricity without emission of greenhouse gases
Taking into account the peculiarities of various carbonaceous ma terials, the synthesis procedure of the mixed oxide–carbon composite type electrocatalyst supports with different Ti0.8Mo0.2O2/C ratios was successfully optimized for use of Vulcan, unmodified Black Pearls 2000 (BP) and function alized F-BP carbon materials
It was demonstrated that the time and temperature of aging and maintenance of the appropriate acidic pH during the synthesis played key role in exclusive formation of the rutile phase, which is essential for good Mo incorporation and enhanced sta bility
Summary
Fuel cells convert chemical energy of hydrogen-rich fuels into elec tricity without emission of greenhouse gases. The key requirements for prospective electrocatalysts in PEM fuel cells involve [2]: (i) high stability in the anticipated pH/potential win dow, (ii) high resistance against electrochemical corrosion, (iii) good electronic and proton conductivity, (iv) high specific surface area, (v) appropriate porosity for mass transfer of liquid fuels or oxygen gas and the minimization of water flooding in electrodes, and (vi) strong inter action between the Pt nanoparticles and the support. Corrosion results in either Pt dissolution or oxidation of the carbon support leading to detachment, Ostwald ripening and agglomeration of platinum nanoparticles [5,6,7] Another issue of the traditional Pt/C catalysts is their sensitivity towards CO poisoning [8,9]. It is important to explore alternative materials that can provide improved stability and increased CO tolerance
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