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Long-Range and Short-Range Structures of Multimetallic Layered Double Hydroxides
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2022-03-10 , DOI: 10.1021/acs.jpcc.2c00121
Wenxian Gou 1, 2 , Xiaoming Wang 3, 4 , Mengqiang Zhu 3 , Dong-Xing Guan 1 , Xinxin Mo 1, 2 , Hongtao Wang 1, 2 , Wei Li 1, 2
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Layered double hydroxides (LDHs) are a family of anionic clays that have wide applications in environmental remediation, catalysis, and nanocomposite materials. These excellent performances heavily depend on the cation arrangements of LDHs, and thus, a thorough understanding of this cation arrangement is of significance to the functional optimization of LDHs. The cation arrangements of LDHs, however, remain obscure because of the small particle size and stacking defects. This study synthesized seven multimetallic layered double hydroxides (LDHs) with a composition of [Me0.66Al0.33(OH)2](CO3, NO3)0.17–0.33·(0.79–1.01)H2O (Me = Co, Ni, and/or Zn) through a coprecipitation method at pH 7.5. Multiple advanced techniques, including pair distribution function, extended X-ray absorption fine structure, wavelet transform analysis, and nuclear magnetic resonance spectroscopy, were employed to characterize the cation arrangement. The results suggest that Co, Ni, and/or Zn are distributed randomly with Al in the seven LDHs, all of which reside in the octahedral site coordinated by six oxygen atoms. The random distribution of Co/Ni/Zn and Al deviates from Pauling’s rule, which would require no edge sharing of AlO6 octahedra in LDHs with a ratio of Me2+/Me3+ equal to 2. The cation disorder of the seven LDHs is likely related to the neutral pH used in the synthetic process. This study provides detailed structural information of the seven LDHs at the atomic level, which helps shed light on the future understanding of the structure–function relationship of short-range structural ordering nanomaterials.

中文翻译:

多金属层状双氢氧化物的长程和短程结构

层状双氢氧化物 (LDH) 是一类阴离子粘土,在环境修复、催化和纳米复合材料中具有广泛的应用。这些优异的性能在很大程度上取决于LDHs的阳离子排列,因此,深入了解这种阳离子排列对于LDHs的功能优化具有重要意义。然而,由于粒径小和堆积缺陷,LDH 的阳离子排列仍然模糊不清。本研究合成了 7 种多金属层状双氢氧化物 (LDHs),其组成为 [Me 0.66 Al 0.33 (OH) 2 ](CO 3 , NO 3 ) 0.17–0.33 ·(0.79–1.01)H 2O(Me = Co、Ni 和/或 Zn)在 pH 7.5 下通过共沉淀法。采用对分布函数、扩展X射线吸收精细结构、小波变换分析和核磁共振光谱等多种先进技术来表征阳离子排列。结果表明Co、Ni和/或Zn在七个LDH中与Al随机分布,所有这些都位于由六个氧原子配位的八面体位置。Co/Ni/Zn 和 Al 的随机分布偏离了鲍林规则,这要求在具有 Me 2+ /Me 3+比率的 LDH 中没有 AlO 6八面体的边缘共享等于 2。七种 LDH 的阳离子紊乱可能与合成过程中使用的中性 pH 值有关。本研究提供了七种 LDH 在原子水平上的详细结构信息,有助于阐明未来对短程结构有序纳米材料的结构-功能关系的理解。
更新日期:2022-03-10
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