Distribution of Gallium Nanocrystals in Ga/MCM-41 Mesocomposites by Continuous-Flow Hyperpolarized ~129Xe NMR Spectroscopy

摘要

The distribution of gallium nanocrystals in mesoporous MCM-41 host were analyzed by continuous-flow hyperpolarized ~129Xe NMR spectroscopy. In contrast to nuclear TEM images for the high metal contents, laser-polarized ~129Xe probe can detect the whole distribution of gallium in the MCM-41 host. It is found that gallium nanocrystals are included in the mesochannels of MCM-41; a part of them also remains in the interparticle voids. The distribution of gallium metal in MCM-41 is beterogeneous. Not all the mesochannels host metallic gallium even at a high gallium loading of 65.1 wt percent. Variable temperture measurements can provide information on the xenon adsorption parameters. This approach opens a sensitive way to probe the distribution of high content species in porous host materials.