利用固体核磁共振技术实验表征MgGaAl水滑石结构

Revealing the Eff ect of Ga/Al Ratios on the Local Environment of MgGaAl-LDH with SolidState Nuclear Magnetic Resonance Spectroscopy

水滑石(Layered Double Hydroxide,LDH)因其在催化、医药和吸附等方面的广泛应用受到了众多研究者的关注。由于这些优异的性能与LDH层板中的金属阳离子排列顺序有着直接的联系,因此要实现对LDH材料的有效调控,首先,要对材料的局域结构进行深入研究,其中固体核磁共振(Solid state NMR)是一种可从分子/原子尺度探测局部结构的强有力的工具。本文采用简单的共沉淀法将Ga3+引入MgAl-LDH层板中,进一步调控Ga/Al比,合成了MgGaAl-LDH系列材料。27Al NMR及71Ga NMR的结果表明,Ga3+的引入对27Al、71Ga周围的局部环境影响很小,因此不会引起相应的局部结构变化,且27Al NMR和71Ga NMR的四极参数之间存在相关性。该结论可能为设计、制备特定功能的MgGaAl-LDH材料及以MgGaAl-LDH为前驱体的新型功能材料提供理论依据和基础。

Layered double hydroxide(LDH)has attracted the attention of many researchers due to its wide applications in catalysis,medicine and adsorption,and etc.Since these excellent properties are directly related to the arrangement order of metal cations in the LDH laminates,the local structure of the materials should be studied in depth first to achieve effective regulation of LDH materials,where solid state magnetic resonance(SSNMR)is a powerful tool for detecting local structures at the molecular/atomic scale.In this paper,the MgGaAl-LDH series materials were synthesized by introducing Ga3+into the MgAl-LDH layer plate by a simple coprecipitation method to further regulate the Ga/Al ratio.The results of 27Al NMR and 71Ga NMR show that the introduction of Ga3+has little effect on the local environment around the 27Al and 71Ga,so it does not cause corresponding local structural changes,and there is a correlation between the quadrupole parameters of 27Al NMR and 71Ga NMR.This conclusion can provide a theoretical basis for the design and preparation of MgGaAl-LDH materials and new functional materials with MgGaAl-LDH as precursor.