Structural and electrocatalytic features of Pt/C catalysts fabricated in supercritical carbon dioxide
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Pt/carbon black samples fabricated from dimethyl (1,5-cyclooctadiene) platinum(II) in supercritical CO2 are characterized in relation to possible applications in methanol fuel cell. The problem of precise material characterization is addressed in frames of X-ray diffractometry, transmission electron microscopy, and electrochemical techniques of the true surface area determination. The catalysts with Pt loading of 20–40 wt.% consist of nm-size particles, with the lattice defectiveness dependent on the fabrication mode. To check the effect of support, various types of carbon blacks (Vulcan XC72R and acetylene black AC-1) are used. In contrast to commercial HiSpec catalysts, no pronounced increase of particle size with Pt loading is found. Specific steady-state activity towards methanol oxidation appears to be essentially higher than for commercial catalysts, mostly because the self-poisoning effects are less pronounced. As for poisoning of Pt with organic species (resulting from the ligand of precursor), its effects are demonstrated to be minor after CO or methanol adsorption accompanied by desorption of contaminating by-product.
KeywordsSupercritical carbon dioxide Pt nanoparticles Carbon supports Methanol electrooxidation X-ray diffractometry
The work was done under financial support from the National Innovation Company New Energy Project and also was partly supported by RFBR, project 08-03-00854-а. The authors are grateful to Prof. P.M. Valetsky and A.S. Kotosonov for the samples of acetylene black AC-1 and fruitful discussions. M.O.G. and E.E.S.-G. are grateful to Russian Academy of Sciences for the support within Presidium's Basic Researches Program No 27.
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