| Abstract
| - Carbon nanomaterials, including herringbone graphite carbon nanofibers (GNFH), multiwalledcarbon nanotubes (MWCNT), and carbon black, were surface-modified by a new poly(vinylpyrrolidone)(PVP) grafting process as well as by the conventional acid-oxidation (AO) process, and characterized byFTIR, TGA, Raman, HRTEM, XRD, and XPS measurements. Pt nanoparticles of 1.8 nm were evenlydeposited on all PVP-grafted carbon nanomaterials. The effects of the two surface modification processeson the dispersion, average Pt nanoparticle sizes, the electrocatalytic performance, and electricalconductivities of Pt−carbon nanocomposites in direct methanol oxidation were systematically studied andcompared. It was found that the PVP-grafted carbon nanomaterials have much less loss in the electricconductivity and thus better electrocatalytic performance, 17−463% higher, than their corresponding acidoxidation-treated nanocomposites. The electrocatalytic performance of the Pt−carbon nanocompositesdecreases in the following order: Pt−PVP−GNFH> Pt−PVP−MWCNTarc> Pt−AO-MWCNTarc> Pt−PVP−MWCNTCVD> Pt−AO-MWCNTCVD> Pt−XC-72R > Pt−AO-GNFH, with the Pt−PVP−GNFHnanocomposite having ∼270% higher performance than that of the Pt−Vulcan XC-72R nanocomposite. Inaddition, PtRu−PVP−GNFH shows even better (50% higher) electrocatalytic activity than the Pt−PVP−GNFH nanocomposite at a 0.6 V applied voltage.
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