Preparation, characterization and catalytic properties of Pd-decorated carbon nanotubes possessing different linkers

Abstract

To investigate the relationship between the linker length and the catalytic activities of metal-decorated CNTs, three samples were prepared with different linker molecules, viz. NaSH, HSCH 2 CH 2 SH, and C 2 H 2 N 2 S 3 . The structures of the prepared samples were characterized using transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The analysis of the TEM images and XRD patterns showed that the Pd nanoparticles strongly adhered to the outside of the CNTs, with average particle sizes of $3 nm, $5 nm, and $6 nm for samples A, B and C, respectively. The XPS spectra revealed that the Pd species on the Pd-decorated CNTs consisted of Pd 0 , Pd 2+ and Pd 4+ . The oxidized Pd species were formed by the interaction of the electron-donor Pd 0 atoms with the electrophilic neighboring protons (H + ) during the sample preparation. The oxidized Pd species become more abundant with increasing linker length, causing a decrease of their catalytic activities in organic and electrocatalytic reactions. Nevertheless, all of the samples exhibited higher activity in organic and electrocatalytic reactions than that of the reference systems.

Design and synthesis of palladium/graphitic carbon nitride/carbon black hybrids as high-performance catalysts for formic acid and methanol electrooxidation

“…Additionally, it is found that the Pd 3d spectrum in Fig. 2(d) consists of four components, which are metallic Pt (335.8 and 341.1 eV), Pd 2þ (337.1 and 342.5 eV), Pd 4þ (338.6 and 343.9 eV) and Pd satellite peak (342.7 eV) [6,35,36]. Compared with the Pd-CB sample (335.2 eV), the Pd peak position of Pd-gCN-CB-30 (335.8 eV) shifted to higher binding energies, which is related to the enhanced attraction force between Pd atoms and g-C 3 N 4 /carbon black support [37,38].…”

Modified Nanocarbons for Catalysis

“…Nanotubes endowed with thiols 87 , 88 , and 89 , introduced through the carboxylic groups produced after oxidation of the tubes, were among the first modified‐CNT materials used for stabilizing Pd NPs and tested as phosphine free recyclable heterogeneous catalysts in the Suzuki and Sonogashira reactions (Figure ). Esterification or amidation of carboxylic groups have been exploited in order to covalently anchor proper ligands for Pd(II) Schiff base complexes or Pd NPs to oxidized nanotubes for preparing nanocatalysts 90 – 93 .…”

Novel sulfonated multi‐walled carbon nanotubes filled chitosan composite membrane for fuel‐cell applications

“…XRD analysis was performed to characterize changes in the crystalline structure of sulfonated MWCNTs. The characteristic diffraction peaks of MWCNTs at 2θ = 25.46° and 2θ = 43.13° represent the hexagonal graphite structure, as shown in Figure (a,b) and Table . The insertion of monomer during modification might destroy the regular stack in MWCNTs, resulting in the disappearance of diffraction peaks at 2θ = 13.69° and 2θ = 13.96° [Figure (a,b)].…”