Six Pt-Ru/carbon fiber nanocomposites have been prepared by using a bimetallic precursor as a source of metal. Carbon fiber supports include singled-walled nanotubes, multiwalled nanotubes, or graphitic carbon nanofibers having either platelet, wide herringbone, or narrow tubular herringbone atomic structures. Preparative procedures have been optimized to enhance the performance of these nanocomposites as anode electrocatalysts in direct methanol fuel cells. Pt-Ru nanoparticles are the major metal-containing component of these nanocomposites along with variable amounts of Ru metal. A range of direct methanol fuel cell performance is observed with a Pt-Ru/narrow tubular herringbone graphitic carbon nanofiber nanocomposite showing the highest performance. This performance is equivalent to that recorded for an unsupported Pt-Ru colloid at an anode catalyst loading of 2.7 mg total metal/cm 2 , but 64% greater than that of the unsupported Pt-Ru colloid at a lower catalyst loading of 1.5 mg/cm 2 .

Multistep deposition and reactive decomposition of a precursor molecule containing one Pt and one Ru atom on herringbone graphitic carbon nanofibers (GCNFs) affords a Pt-Ru/GCNF nanocomposite containing Pt-Ru alloy nanoclusters widely dispersed on the GCNF support. The nanocomposite has a total metal content of 42 wt % with a bulk Pt/Ru atomic ratio of ca. 1:1, and metal alloy nanoclusters having average particle sizes of 6 nm as calculated from XRD peak widths or 7 nm as measured directly from TEM images. XRD and electrochemical analysis of the nanocomposite as-prepared and stored under ambient conditions reveals the presence of small amounts of Ru metal and oxidized metal species. Comparative testing of this nanocomposite and an unsupported Pt-Ru colloid of similar surface area and catalyst particle size as anode catalysts in a working direct-methanol fuel cell (DMFC) reveals a 50% increase in performance for the Pt-Ru/GCNF nanocomposite. More detailed study of the catalytic performance of metal alloy/GCNF nanocomposites as DMFC anode catalysts appears to be warranted.

ZrW2O8 is obtained as microparticulate powder following traditional methods or as nanoparticulate powder using an inverse micelle sol−gel synthesis strategy. As-prepared ZrW2O8 powders, surface-derivatized with (3-aminopropyl)siloxy linker molecules, disperse well in BTDA-ODA polyamic acid resins to give thermally cured ZrW2O8/polyimide hybrid films showing good wetting of embedded ceramic particles. Measured CTE values of ZrW2O8/BTDA-ODA hybrid films containing 0−50 wt % (0−22 vol %) ceramic loading show a controlled reduction in thermal expansion with increasing ceramic content. Reduction in CTE is modeled best assuming mixed-law behavior with incorporation of an interfacial phase region. A 22 vol % ceramic loading gives a 30% (10 ppm/K) reduction of CTE. ZrW2O8/BTDA-ODA films containing 0.8 vol % (3 wt %) ceramic loading exhibit unusually low thermal expansion, although the significance of this observation remains to be confirmed.