Ge Jiachen, Ohata Yusuke, Fukuda Atsushi, Tokumoto Yuki, Ohnishi Takeshi, Moteki Takahiko, Ogura Masaru
Institute of Industrial Science, The University of Tokyo, Komaba 4-6-1, Meguro, Tokyo 153-8505, Japan.
Inorg Chem. 2022 May 23;61(20):7859-7868. doi: 10.1021/acs.inorgchem.2c00452. Epub 2022 May 12.
To the best of our knowledge, this is the first report on the rapid one-pot synthesis of a unique core-shell-structured zeolitic imidazolate framework (ZIF) using Co(III) and Zn(II) precursors. The key to obtaining this unique structure is the use of a Co(III) precursor as the starting material. Transmission electron microscopy (TEM) reveals that Co was present within a 30-nm-thick shell layer of the ZIF material. Thermal decomposition of the ZIF material affords core-shell-structured carbon nanoparticles that have Co on the external surface of the carbon grain. We have previously demonstrated that this carbonaceous material obtained by thermal decomposition exhibited high performance as an adsorbent for nitric oxide, even in the presence of excess oxygen and water vapor, and therefore, it was a suitable material for NO elimination at low temperatures. The growth mechanism of the synthesized ZIF particles and the differences between synthesized ZIF and conventional Co(II)-ZIF-67 are discussed. The reactivity of the Co(III) precursor is much lower than that of the Co(II) species, leading to slower precipitation of Co(III) than that of Zn(II), thus forming the core-shell structure.
据我们所知，这是首次关于使用钴（III）和锌（II）前驱体快速一锅法合成独特核壳结构沸石咪唑酯骨架（ZIF）的报道。获得这种独特结构的关键是使用钴（III）前驱体作为起始原料。透射电子显微镜（TEM）显示，钴存在于ZIF材料30纳米厚的壳层内。ZIF材料的热分解产生核壳结构的碳纳米颗粒，在碳颗粒的外表面有钴。我们之前已经证明，通过热分解得到的这种含碳材料即使在存在过量氧气和水蒸气的情况下，作为一氧化氮吸附剂也表现出高性能，因此，它是低温下消除NO的合适材料。讨论了合成的ZIF颗粒的生长机理以及合成的ZIF与传统钴（II）-ZIF-67之间的差异。钴（III）前驱体的反应活性远低于钴（II）物种，导致钴（III）的沉淀比锌（II）慢，从而形成核壳结构。
