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

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, HSCH2CH2SH, and C2H2N2S3. 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 similar to 3 nm, similar to 5 nm, and similar to 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, Pd2+ and Pd4+. The oxidized Pd species were formed by the interaction of the electron-donor Pd0 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