Enhanced oxygen reduction reaction performances were achieved on size-controlled Pt nanoparticle catalysts prepared by the copolymerization of a Pt4-pyrrole complex and pyrrole monomer in the presence of multi-wall carbon nanotubes.

Fine Pt nanoparticles functionalized with Gd 3+ hydroxide/oxide species were prepared on multiwalled carbon nanotubes (MWCNTs) containing polypyrrole matrix overlayers and found to exhibit remarkable electrocatalytic performance in the oxygen reduction reaction (ORR). Characterization via transmission electron microscopy, scanning transmission electron microscopy with electron energy loss spectroscopy, X-ray absorption fine structure, and X-ray photoelectron spectroscopy revealed that the Gd 3+ hydroxide/oxide species were located in close proximity to the Pt 0 nanoparticles on the MWCNTs. The prepared Pt nanoparticle−Gd hydroxide/oxide composites exhibited superior ORR activity to Gd-free Pt nanoparticles prepared in a similar manner, and the decoration with the Gd species suppressed Pt oxidation and accelerated Pt oxide reduction, as demonstrated by cyclic voltammetry and in situ Pt L III -edge X-ray absorption near-edge structure analysis under potential application. The effect of the Gd loading on the ORR performance was also examined, revealing the existence of an optimal Gd loading beyond which further Gd incorporation resulted in aggregation of the Gd 3+ domains and decreased crystallinity of the Pt nanoparticles.

A novel multiwall carbon nanotube (MWCNT) and polypyrrole (PPy) composite was found to be useful for preparing durable Pt nanoparticle catalysts of highly regulated sizes. A new pyrene-functionalized Pt complex was attached to the MWCNT surface which was functionalized with PPy matrix to yield Pt complex/PPy/MWCNT composites without decomposition of the Pt complex units. The attached Pt complexes in the composite were transformed into Pt nanoparticles with sizes of 1.0-1.3 nm at a Pt loading range of 2 to 4 wt %. The Pt nanoparticles in the composites were found to be active and durable catalysts for the N-alkylation of aniline with benzyl alcohol. In particular, the Pt nanoparticles with PPy matrix exhibited high catalyst durability in up to four repetitions of the catalyst recycling experiment compared with nonsize-regulated Pt nanoparticles prepared without PPy matrix. These results demonstrate that the PPy matrix act to regulate the size of Pt nanoparticles, and the PPy matrix also offers stability for repeated usage for Pt nanoparticle catalysis.