Carbon nanofibers as supports for metal nanoparticles

Abstract

The easy synthesis of transition metal nanoparticles supported on three types of carbon nanofibers (platelet: CNF-P, tubular: CNF-T, herringbone: CNF-H) and nitrogen-doped CNF-H (N-CNF-H) is accomplished by pyrolysis of metal carbonyl clusters such as Ru3(CO)12, Rh4(CO)12, and Ir4(CO)12, and alkene complexes such as Pd2(dba)3·CHCl3 and Pt(dba)2 [dba: dibenzylideneacetone]. Transmission electron microscopy of these CNFs with immobilized metal nanoparticles (M/CNFs and M/N-CNF-H) showed that metal nanoparticles whose size could be controlled, existed on the CNFs, and that their location was dependent on the surface nanostructure of the CNFs: on the edge of the graphite layers (CNF-P), in the tubes and on the surface (CNF-T), and between the layers and on the edge (CNF-H). Among these M/CNFs, Ru/CNF-P and Rh/CNF-T showed excellent catalytic activity towards arene hydrogenation with high reusability and functional group tolerance, while the Pt/CNF-P behaves as an efficient catalyst for the hydrogenation of substituted nitroarenes to the corresponding aniline derivatives with the other functional groups remaining intact. Pt and Pd nanoparticles supported on N-CNF-H act as poisoning catalysts for the transformation of internal alkynes to (Z)-alkenes over Pd/N-CNF-H, and for the transformation of nitroarenes to the corresponding anilines and N-hydroxylamines over Pt/N-CNF-H. [TANSO 2015 (No. 266) 35–40.]