A vertically aligned carbon nanotube array structure enhances water flux in polyethersulfone ultra-filtration membranes.

In this paper we report on an inter-diffusion polymerization method to encapsulate polyaniline (PANi) chains inside multiwalled carbon nanotubes (MWCNTs) based on CNT nano-porous membranes. The MWCNT's inner cavity with a diameter around 15 nm is designed to be the only path for the diffusion of the aniline monomer and the initiator, which achieves an efficient and controllable infilling of PANi inside the CNT cavity. The energy filtered transmission electron microscopy (EFTEM) and Raman spectroscopy confirm the successful encapsulation of PANi chains inside CNTs. The new PANi@CNT hybrid exhibits excellent gas sensitivity towards NH 3 or HCl in a wide concentration range. This new method (inter-diffusion polymerization) is believed to be much more efficient and tunable in preparing novel endohedral nanotube materials compared to traditional capillary infilling approaches.

In this paper we demonstrate a novel complex array structure comprising well-aligned Au nanorods (10 nm in diameter) encapsulated inside 15 nm radius multiwalled carbon nanotubes (MWCNTs). A pre-aligned and open-ended nanoporous MWCNT membrane is used as the starting material. Au nanorods are precisely deposited and aligned inside the hollow channels of CNTs by inter-diffusing the HAuCl4 precursor and the reductant solution. Ultra-long Au nanowires and spherical Au nanoparticles are also observed in the CNT cavity with the same diameter in special cases. Using high-resolution TEM (HRTEM), scanning transmission electron microscopy (STEM), 3-dimensional TEM (3D-TEM) and energy dispersive X-ray spectroscopy (EDX), the precise location and composition of the encapsulated Au components with various structures are confirmed. This aligned Au@CNT endohedral material has important potential applications in nanocatalysis, waveguides, as well as in novel plasmonic devices.