The schematic illustration on the concept of fabrication process for hybrid nanopore-structured copper oxide.
(a) Scanning electron microscopy (SEM) image from a polished transverse section (i.e., the extrusion direction is normal to the plane of the image) of the as-extruded Cu/CNT nanocomposite precursor rod ( diameter and 20 mm length) produced by consolidation of mechanically milled Cu/CNT nanocomposite powders. The uniformly mixed structure is composed of homogeneously dispersed Cu- and CNT-rich regions corresponding, respectively, to lighter and darker regions. (b) STEM image and inset EELS results (scanned following the red line right to left beginning at position 1) obtained from the Cu/CNT as-extruded nanocomposite precursor rod revealing microstructural and compositional details. The size range of the CNTs that are homogeneously mixed with Cu varies from in diameter to in length.
Microstructural characterization of the copper oxide foam prepared by annealing the precursor at 723 K for 3 h in air. (a) SEM image of polished section showing that the copper oxide foam is composed of homogeneously dispersed macroporous cells (dark labeled region) linked together by continuously connected copper oxide ligaments (lighter region). (b) Magnified SEM image of the porous structure with macropores in diameter uniformly mixed with and separated by copper oxide ligaments (white regions). (c) STEM image detailing the surface and interior wall structures of an individual copper oxide ligament. (d) BF TEM image showing nominally spherical nanopores (marked by arrows) located on the surface of the continuously connected copper oxide ligaments. The size range of the nanopores is around 20 nm in diameter, which is close to the initial diameter of the CNTs. The nanoporosity of the oxide struts separating neighboring macropores is a direct consequence of CNT oxidation and volatilization.
(a) XRD patterns from the starting Cu/CNT nanocomposite powders, the as-extruded nanocomposite precursor rod, and the copper oxide foam after heating in air at 723 K for 3 h. In the Cu/CNT nanocomposite powders, the crystalline peaks correspond predominantly to elemental Cu along with broad reflections from the CNTs. The crystalline peaks in the oxide foam are the result of the oxidation of the nanoscale Cu in the precursor upon annealing and can be indexed as and CuO phases. (b) High-resolution TEM image showing that the copper oxide ligaments contain CuO nanocrystallites. An individual CuO nanocrystal in size is presented. The lattice spacing of the CuO nanocrystal is 0.252 nm, which corresponds to the interlayer spacing of the planes in the CuO crystal lattice. (c) SADP obtained from the random crystallographic orientation of the CuO nanocrystals.
(a) Comparison of the volume change rate of gas flow vs saturation time for hybrid and simple nanoporous foams. (b) Schematic description of adsorption rate through comparing the energy diagram with different surface conditions.
The measured properties of hybrid and simple porous structured material.
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