Size Regulation and Stability Enhancement of Pt Nanoparticle Catalyst via Polypyrrole Functionalization of Carbon-Nanotube-Supported Pt Tetranuclear Complex.

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 Pt4 complex was attached to the MWCNT surface which was functionalized with PPy matrix to yield Pt4 complex/PPy/MWCNT composites without decomposition of the Pt4 complex units. The attached Pt4 complexes in the composite were transformed into Pt0 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.