Poly(vinylpyrrolidone)-Modified Graphite Carbon Nanofibers as Promising Supports for PtRu Catalysts in Direct Methanol Fuel Cells

• Published in: Journal of the American Chemical Society Vol. 129; no. 32; pp. 9999 - 10010
• Main Authors: Hsin, Yu Lin, Hwang, Kuo Chu, Yeh, Chuin-Tih
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 15.08.2007
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja072367a

Carbon nanomaterials, including herringbone graphite carbon nanofibers (GNFH), multiwalled carbon 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 by FTIR, TGA, Raman, HRTEM, XRD, and XPS measurements. Pt nanoparticles of 1.8 nm were evenly deposited on all PVP-grafted carbon nanomaterials. The effects of the two surface modification processes on the dispersion, average Pt nanoparticle sizes, the electrocatalytic performance, and electrical conductivities of Pt−carbon nanocomposites in direct methanol oxidation were systematically studied and compared. It was found that the PVP-grafted carbon nanomaterials have much less loss in the electric conductivity and thus better electrocatalytic performance, 17−463% higher, than their corresponding acid oxidation-treated nanocomposites. The electrocatalytic performance of the Pt−carbon nanocomposites decreases 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−GNFH nanocomposite having ∼270% higher performance than that of the Pt−Vulcan XC-72R nanocomposite. In addition, PtRu−PVP−GNFH shows even better (50% higher) electrocatalytic activity than the Pt−PVP−GNFH nanocomposite at a 0.6 V applied voltage.