电子断层扫描技术在催化纳米材料重构中的研究

Electron tomography study on the reconstruction of catalytic materials at nanometer scale

揭示纳米尺度下催化材料结构与性能之间的关系,透射电镜技术是一种不可或缺的表征方法。本文通过透射电镜形貌像、高分辨透射电子显微(high resolution transmission electron microscopy,HRTEM)像及高角环形暗场(high angle annular dark field,HAADF)方法,并运用电子断层扫描技术(electron tomography,ET),揭示了Pt Co合金纳米颗粒的物相结构以及表面包围晶面形态信息,重构出催化剂纳米颗粒的凹面六四面体的三维形态结构。此外,本文将电子断层扫描技术扩展到负载型多孔沸石咪唑脂骨架结构材料(ZIF-8)和介孔Al_2O_3分子筛两种材料的分析研究,在一定程度上弥补了常规透射电镜显微成像仅能提供二维投影信息的不足。最后基于目前ET技术的优势和不足,讨论并展望了透射电镜相关ET硬件技术的发展和应用前景。

Transmission electron microscopy（ TEM） is an indispensable tool for studying the features of catalytic materials at nanometer scale. Combining bright field imaging,high-resolution TEM（ HRTEM）,and high-angle annular dark field-scanning TEM（（ HAADF-STEM） imaging,the phase structure and surface lattice arrangements of single Pt COnanoparticles were revealed. In addition,electron tomography（ ET） was employed to study the three dimensional（ 3 D） geometrical features of the Pt Co nanocrystal particles. It was found that the morphology of Pt Co nanoparticles was a concave six-four polyhedron. ET was further employed to investigate the 3 D structures of Zeolitic Imidazolate Framework-8（ ZIF-8） and catalysts embedded in mesoporous Al2O3 molecular sieves matrix,which were difficult to be achieved by two dimensional imaging in conventional TEM. Last,the recent progress and application of the ET technologies that benefiting from the fast development of hardware and software were briefly prospected.