A comprehensive nanoscale understanding of layered double hydroxide (LDH) thermal evolution is critical for their current and future applications as catalysts, flame retardants and oxygen evolution performers. In this report, we applied in situ transmission electron microscopy (TEM) to extensively characterise the thermal progressions of nickel-iron containing (Ni-Fe) LDH nanomaterials. The combinative approach of TEM and selected area electron diffraction (SAED) yielded both a morphological and crystallographic understanding of such processes. As the Ni-Fe LDH nanomaterials are heated in situ, an amorphization occurred at 250 °C, followed by a transition to a heterogeneous structure of NiO particles embedded throughout a NiFe₂O₄ matrix at 850 °C, confirmed by high-resolution TEM and scanning TEM. Further electron microscopy characterisation methodologies of energy-filtered TEM were utilised to directly observe these mechanistic behaviours in real time, showing an evolution and nucleation to an array of spherical NiO nanoparticles on the platelet surfaces. The versatility of this characterisation approach was verified by the analogous behaviours of Ni-Fe LDH materials heated ex situ as well as parallel in situ TEM and SAED comparisons to that of an akin magnesium-aluminium containing (Mg-Al) LDH structure. The in situ TEM work hereby discussed allows for a state-of-the-art understanding of the Ni-Fe material thermal evolution. This is an important first, which reveals pivotal information, especially when considering LDH applications as catalysts and flame retardants.

对层状双氢氧化物（LDH）热生成的全面纳米了解对于它们当前和将来作为催化剂，阻燃剂和氧气生成性能的应用至关重要。在本报告中，我们应用了原位透射电子显微镜（TEM）广泛地表征了含镍铁（Ni-Fe）LDH纳米材料的热过程。TEM和选择区域电子衍射（SAED）的组合方法对这种过程产生了形态学和晶体学的理解。随着原位加热Ni-Fe LDH纳米材料，在250°C时发生非晶化，然后过渡到整个NiFe ₂ O ₄内嵌的NiO颗粒的异质结构高分辨率TEM和扫描TEM证实850°C时的基质。能量过滤TEM的其他电子显微镜表征方法被用于直接实时实时观察这些机械行为，显示了在血小板表面上球形NiO纳米颗粒阵列的演化和成核。异位加热的Ni-Fe LDH材料的相似行为以及与类似的含镁铝（Mg-Al）LDH结构的原位平行TEM和SAED比较，证明了这种表征方法的多功能性。在此讨论的原位TEM工作允许对Ni-Fe材料的热演化有最新的了解。这是重要的第一，它揭示了关键信息，尤其是在考虑将LDH应用作为催化剂和阻燃剂时。