层状双金属氢氧化物形成机理的研究现状

Research progress of layered double hydroxide formation mechanisms

近年来,层状双金属氢氧化物(LDH)凭借特殊的层状结构、极强的可调控性能、优异的环境兼容性及显著的应用效果等特点,在环保、催化、储能、传感等领域得到广泛关注。国内外多数研究集中于LDH可控合成工艺的改进完善及LDH的应用探索,但迄今对制备LDH时涉及其组成结构形貌的变化过程,即其形成机理的关注较少,相关机制解释模糊,深入研究其形成过程对于可控制备具有独特形貌和特定组成的LDH及开发更深层次的应用具有至关重要的作用。本文介绍了LDH层板形成机理的3个主要研究方向,即以二价金属氢氧化物的存在为基础、以三价金属氢氧化物的存在为基础和拓扑相变机制,并分别进行了阐述辨析及对比分析,发现LDH层板的形成是一个极其复杂的过程,多种机制往往共同作用,总结认为固液及液液反应在初期成核阶段占据主导地位,各自作用程度及不同层板构筑机制产生的主导作用易受到外界环境因素影响,而更为普遍的LDH形成机制解释需要归纳总结更多LDH层板构筑的区别和规律,宏观和微观上探索形成过程的内在机理及科学本质,以期为LDH开发拓展提供理论基础。

Layered double hydroxide（LDH）are a kind of promising special multifunctional layered materials,which have the excellent regulatable capability,perfect environmental compatibility and remarkable efficiency,so they have been studied extensively in environmental protection,catalysis,energy storage,transducer and other fields.Most researches are conducted on the improvement of tailored synthesis methods and application of LDH,whereas the research on the transformation of LDH（composition,structure and morphology）is rare,especially on the general formation mechanism of LDH.The controllable preparation and in-depth applications of LDH with unique morphology and specific composition are highly demanded.An overview and comparison are presented on the interpretations of primary LDH laminate formation mechanisms which are the existence of divalent metal hydroxide,the existence of trivalent metal hydroxides and the direct topological phase transition mechanism.The solid-liquid and liquid-liquid reactions are thought to play a dominant role in the initial nucleation stage,while the multiple mechanisms,the various influences and the mastery reaction are easily affected by the external conditions.To obtain a more universal mechanistic insight on LDH formation and provide a theoretical basis for the prospective development of LDH,a general formation mechanism need to be clarified,which requires explanations from the conclusive building rules and difference of LDH laminate as well as the internal mechanism and scientific nature of the formation process in macro and micro perspectives.