Design and Synthesis of Oriented Guest-Host Nanostructures for Enhanced Membrane Performances

Hu, M.Z.

Oak Ridge National Laboratory

关键词: 30 Direct Energy Conversion;    Orientation;    14 Solar Energy;    Membranes;    Stability;   

DOI  :  10.2172/885953
RP-ID  :  R05-124383
RP-ID  :  DE-AC05-00OR22725
RP-ID  :  885953

美国|英语

来源: UNT Digital Library

【 摘 要 】

This project has demonstrated a novel nanomaterial design concept and a synthesis method for ''guesthost'' type superionic-conducting nanocomposite membranes. This concept consists of nanophases of oxide electrolyte nanograins (guest) encapsulated inside the nanopore channels of an oxide layer matrix (host), with channels oriented perpendicular to the layer surface. Using ionic conducting YSZ (yttrium stabilized zirconia) as a special case, we have shown that the host-guest design allows orientation of a large number channels, allowing a high density of nanograin boundaries/interfaces to be built into the film to enhance cross-membrane conductivity. This structure allowed conductivity measurements with impedance spectroscopy to be performed for the first time at room temperature. Cross-membrane conductivity values at low temperature ranges of interest are the higher than any reported values. The conductivity-enhancing mechanisms could be attributed to (1) controlled orientation and increased number density of YSZ nanograin-host interfaces and (2) creation and stabilization of YSZ nanocrystalline phases inside nanopore channels (<10 nm dia.). This successful initial demonstration of host-guest nanostructures is expected to have direct impact on fuel cell technologies, and may also have beneficial use in a broad range of applications such as in solar cells, sensors, chemical/gas separations, catalysis, and magnetic memory devices. This work may also lead to a new way to develop membrane technologies that offer orders-of-magnitude higher permeability and selectivity, as well as improved thermal stability of the desirable nanocrystalline phases.