Kamei Ryoma, Hosomi Takuro, Kanao Eisuke, Kanai Masaki, Nagashima Kazuki, Takahashi Tsunaki, Zhang Guozhu, Yasui Takao, Terao Jun, Otsuka Koji, Baba Yoshinobu, Kubo Takuya, Yanagida Takeshi
Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan.
Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasuga-Koen, Kasuga, Fukuoka 816-8580, Japan.
ACS Appl Mater Interfaces. 2021 Apr 14;13(14):16812-16819. doi: 10.1021/acsami.0c22709. Epub 2021 Mar 30.
Seeded crystal growths of nanostructures within confined spaces offer an interesting approach to design chemical reaction spaces with tailored inner surface properties. However, such crystal growth within confined spaces tends to be inherently difficult as the length increases as a result of confinement effects. Here, we demonstrate a space-confined seeded growth of ZnO nanowires within meter-long microtubes of 100 μm inner diameter with the aspect ratio of up to 10 000, which had been unattainable to previous methods of seeded crystal growths. ZnO nanowires could be grown via seeded hydrothermal crystal growth for relatively short microtubes below the length of 40 mm, while any ZnO nanostructures were not observable at all for longer microtubes above 60 mm with the aspect ratio of 600. Microstructural and mass spectrometric analysis revealed that a conventional seed layer formation using zinc acetate is unfeasible within the confined space of long microtubes as a result of the formation of detrimental residual Zn complex compounds. To overcome this space-confined issue, a flow-assisted seed layer formation is proposed. This flow-assisted method enables growth of spatially uniform ZnO nanowires via removing residual compounds even for 1 m long microtubes with the aspect ratio of up to 10 000. Finally, the applicably of ZnO-nanowire-decorated long microtubes for liquid-phase separations was demonstrated.
在受限空间内进行纳米结构的籽晶生长为设计具有定制内表面性质的化学反应空间提供了一种有趣的方法。然而，由于受限效应导致长度增加，在受限空间内进行这种晶体生长本质上往往很困难。在这里，我们展示了在内径为100μm、长为1m的微管内进行ZnO纳米线的空间受限籽晶生长，其长径比高达10000，这是以前的籽晶生长方法无法实现的。对于长度小于40mm的相对较短的微管，可以通过籽晶水热晶体生长来生长ZnO纳米线，而对于长径比为600、长度大于60mm的较长微管，根本观察不到任何ZnO纳米结构。微观结构和质谱分析表明，由于形成了有害的残留锌络合物，在长微管的受限空间内使用醋酸锌形成传统的籽晶层是不可行的。为了克服这个空间受限问题，我们提出了一种流动辅助籽晶层形成方法。这种流动辅助方法即使对于长径比高达10000的1m长微管，也能通过去除残留化合物来实现空间均匀的ZnO纳米线的生长。最后，展示了用ZnO纳米线装饰的长微管在液相分离中的应用。
