Quintelier Matthias, Zintler Alexander, Nakazato Ryosuke, Rosero-Navarro Nataly Carolina, Tadanaga Kiyoharu, Hadermann Joke
EMAT, Department of Physics, University of Antwerp, Antwerp 2020, Belgium.
Faculty of Engineering, Hokkaido University, Kita 13, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan.
ACS Appl Mater Interfaces. 2025 Jul 2;17(26):38587-38596. doi: 10.1021/acsami.5c03313. Epub 2025 Jun 17.
Layered double hydroxides (LDHs) are versatile materials with diverse applications, including catalysis, water separation, adsorption, biomedicine, and fire retardancy. This study investigates the thermal evolution of ZnAl LDH ([ZnAl(OH)] [CO]) using scanning nanobeam electron diffraction, high-resolution transmission electron microscopy, and energy-dispersive X-ray analysis. The structural and morphological changes are examined during heating in both ambient air and vacuum. The pristine ZnAl LDH exhibited edge dislocations and irregular interlayer distances, leading to significant diffuse scattering in the electron diffraction patterns. Both upon heating in ambient air conditions and in vacuum, the characteristic hexagonal LDH morphology transformed into a porous nanostructure. The exact crystal structure transitions differed as a function of the environment. Heating under vacuum conditions first led to a ZnAlO phase with a spinel-type structure, and subsequently to ZnO particles embedded within an AlO matrix. When heated in a closed cell filled with ambient air, the LDH initially transitioned to an Al-doped ZnO-type structure, followed by conversion to a ZnAlO phase. This study is the first gas TEM LDH study and shows the recrystallization behavior of the LDH into the different phases upon heating and uncovers the nanoscale distribution of these phases within the particles, forming ZnAlO, ZnO, and AlO composites.
层状双氢氧化物（LDHs）是具有多种应用的多功能材料，包括催化、水分离、吸附、生物医学和阻燃等。本研究使用扫描纳米束电子衍射、高分辨率透射电子显微镜和能量色散X射线分析来研究ZnAl LDH（[ZnAl(OH)] [CO]）的热演化过程。在环境空气和真空中加热过程中对结构和形态变化进行了研究。原始的ZnAl LDH表现出边缘位错和不规则的层间距离，导致电子衍射图谱中出现明显的漫散射。在环境空气条件下和真空中加热时，特征性的六边形LDH形态均转变为多孔纳米结构。确切的晶体结构转变因环境而异。在真空条件下加热首先导致形成具有尖晶石型结构的ZnAlO相，随后形成嵌入AlO基质中的ZnO颗粒。当在充满环境空气的密闭池中加热时，LDH最初转变为Al掺杂的ZnO型结构，随后转变为ZnAlO相。本研究是首次关于LDH的气体TEM研究，展示了LDH在加热时重结晶为不同相的行为，并揭示了这些相在颗粒内的纳米级分布，形成了ZnAlO、ZnO和AlO复合材料。
