Structural Synthon Approach to the Study of Stacking Faults in the Layered Double Hydroxides of Lithium and Aluminum

A single layer of the Li‐Al layered double hydroxide (LDH) can be considered to be a structural synthon that can be stacked in a number of ways to give rise to the polytypes of the Li‐Al LDH family. The topotactic imbibition of lithium into gibbsite and bayerite precursors gives rise to crystalline 2H and 1M₁ polytypes respectively. In contrast the sample formed through a gel to crystallite route is found to be a 1M₁ polytype with stacking disorders whose local symmetry corresponds to the 1M₂ polytype. On heating, a solid‐solid 1M₁→1H polytype transformation is observed.     

Layered Double Hydroxide as Cordycepin Delivery Nanocarrier

Layered double hydroxides (LDHs), also called “anionic clays”, have received considerable attention due to their technological importance in catalysis, adsorption, optics, nanocomposite engineering materials and medical science1-5. LDHs are layered mate…     

层状双金属氢氧化物/石墨烯复合材料及其在电化学能量存储与转换中的应用

高效的电化学能量存储与转换功能材料及其器件近年来受到了人们的广泛关注。层状双金属氢氧化物/石墨烯（LDH/G）复合物就是一类重要的能源材料。它们兼具LDH和石墨烯的优异的物理、化学性能,同时克服了LDH导电性差和石墨烯片易于团聚的问题;在超级电容器和电化学催化分解水等方面具有广泛应用。本文综述了LDH与化学修饰石墨烯（氧化石墨烯,还原氧化石墨烯及其衍生物）的有效复合的方法及其在电化学能量存储与转换领域中的应用,特别是关于基于该类材料的超级电容器及电化学析氧反应催化的研究;对LDH/G复合材料研究领域中的挑战和未来发展方向做了展望。     

Study on Intercalative Nanohybrid of Cordycepin in Layered Double Hydroxide

A novel negatively charged biomolecule-cordycepin has been intercalated within the gallery spaces of [Mg-Al-NO3]. Results of TEM, PXRD and FF-IR spectroscopy confn-med that cordycepin could be intercalated into [Mg-Al-NO3] intedayers as the charge-compensating species.Initial studies suggest that the new bioinorganic nanocomposite may be used as a novel inorganic reservoir or carder of pharmaceutically active compounds.     

MgAl无机-有机杂化材料对Pb~(2+)的吸附

采用共沉淀法合成了结晶度良好、具有纯水滑石相的Mg-Al型层状双金属氢氧化物(LDH)及其乙二胺四乙酸二钠(EDTA)-LDH无机-有机杂化物,并进行了表征。考察了Mg-AlLDH和EDTA-LDH对Pb2+的吸附作用,其均有很好的吸附能力,EDTA在LDH通道中可能以直立平行方式排列成单层。在相同条件下,EDTA-LDH的吸附速率和吸附量均高于Mg-AlLDH。结果表明,EDTA的插入具有协同增效作用,吸附动力学符合准二级吸附速率方程。吸附等温线可分为吸附阶段和表面沉淀阶段,吸附阶段的等温线符合Freundlich吸附等温式。初始pH值对Pb2+的吸附基本无影响。Pb2+在LDH和EDTA-LDH上的吸附机理主要为表面沉淀,并存在化学键合和静电键合作用,EDTA-LDH存在EDTA与Pb2+的络合作用。     

Polyoxometalate-Incorporated Host-Guest Framework Derived Layered Double Hydroxide Composites for High-Performance Hybrid Supercapacitor†

Metal organic frameworks have been employed as high-performance layered double hydroxide (LDH) composite supercapacitor electrode materials but have shown unsatisfactory redox ability and stability. Herein, a host-guest CuMo-based polyoxometalate-based metal organic framework (POMOF) with copious electrochemically active sites and strong electrochemical redox activities has been effectively coupled with POM-incorporated CoNi-LDH to develop a nanocomposite (NENU-5@CoNi-LDH) by a simple solvothermal method. The designed electrode shows a high specific capacity of 333.61 mAh·g^–1 at 1 A·g^–1. In addition, the novel hybrid symmetric supercapacitor NENU-5@CoNi-LDH/active carbon (AC) demonstrated a high energy density of 80.8 Wh·kg^–1 at a power density of 750.7 W·kg^–1. Interestingly, the nanocomposite of NENU-5@CoNi-LDH exhibits an outstanding capacitance retention of 79% after 5000 charge-discharge cycles at 10 A·g^–1. This work provides a new strategy and will be the backbone for future energy storage research.      

Remote Synthesis of Layered Double Hydroxide Nanosheets Through the Automatic Chemical Robot

As a family of two-dimensional functional materials, layered double hydroxides(LDHs) have the characteristics of adjustable lamellar element type and proportion, variable interlamellar anion, controllable particle size and thickness, providing a robust platform for photo/electro/thermal-catalysis. With the continuous progress of materials science, the synthesis of LDHs is becoming more and more refined. Herein, to achieve the fine preparation of LDHs materials, especailly for the no-chemical/material researchers, we successfully assembled the automatic synthesis device and wrote corresponding computer software to control this device, and the automatic synthesis of bulk and monolayer LDHs nanosheets on a laboratory scale can be realized. This work paves a new labor-saving way for the fine synthesis of LDHs nanostructures, further improving the development of LDHs-based materials.     

聚氯乙烯/层状双氢氧化物纳米复合材料研究进展

聚氯乙烯(PVC)/层状双氢氧化物(LDHs)纳米复合材料相比于纯聚氯乙烯具有更好的热稳定性、力学性能、阻燃抑烟性、耐候性与耐光性等,是一种性能优异并具有广泛应用前景的新型聚合物基纳米复合材料。本文首先介绍了LDHs的化学组成和结构特点,并对其制备过程和性质特点进行了分析和探讨;然后综述了PVC/LDH纳米复合材料的制备、结构表征及性能等方面的最新研究进展,重点阐述了LDHs的表面有机化处理及其对PVC/LDH纳米复合材料制备与性能的重要作用;最后对其应用前景进行展望。     

Adsorption of Metanil Yellow Azoic Dye from Aqueous Solution onto Mg‐Fe‐NO3 Layered Double Hydroxide

We report the preparation and characterization of a layered double hydroxide (LDH) adsorbent for azoic dye, metanil yellow (yellow GX; YGX) removal. The nanoparticles of Mg‐Fe‐LDH‐NO₃ adsorbent were prepared with Mg/Fe molar ratio of 3:1 by a hydrothermal process and coprecipitation method at pH 9.5 and were characterized by X‐ray powder diffraction (XRPD), thermal gravimetric analysis (TGA), elemental analysis, and Fourier transform infrared spectroscopy (FT‐IR). The size and morphology of nanoparticles were examined by scanning electron microscopy (SEM). The XRD patterns indicate that the intercalation of YGX between the LDH layers has not occurred and surface adsorption has happened. In the adsorption experiments, the Gibbs free energy ΔG⁰ values, the enthalpy ΔH⁰, and entropy ΔS⁰ was determined. The isotherms showed that the adsorption of YGX by Mg‐Fe‐LDH‐NO₃ was both consistent with Langmuir and Freundlich equations.     

水滑石负载的钯纳米粒子对水合肼的电催化氧化

利用共沉淀方法制备了载体水滑石(LDH), 通过离子交换法将PdCl2₄^- 插入水滑石层间, 再用水合肼将其还原, 制备得到了水滑石负载的分散状钯纳米粒子(LDH-Pd⁰). 利用X射线衍射(XRD)、透射电镜(TEM)和X射线电子能谱(XPS)等手段对所得样品进行了表征, 结果表明钯纳米粒子能很好地分散在水滑石上. 将该纳米材料修饰的玻碳电极(GCE)用于水合肼的电催化氧化, 该修饰电极表现出很好的电化学催化活性. 用循环伏安法(CV)、计时库仑法(CC)和计时安培法(i-t)对修饰电极的催化活性、有效表面积和水合肼的催化氧化机理等进行了研究. 结果表明水合肼在-0.1 V附近有明显的氧化峰, 在1.0×10^-5-2.0×10^-4 mol·L^-1范围内, 阳极峰电流与水合肼浓度间有良好的线性关系, 其检测限为9.5×10^-7 mol·L^-1. 计算得到GCE, LDH-Pd⁰/GCE 和LDH/GCE电极活化面积分别为0.02089, 0.02762 和0.02496 cm². 推知水合肼的氧化过程有4 电子和4 质子参与, 并且其在电极上的反应是受扩散控制的不可逆过程.     

Determination of Chlorpromazine Hydrochloride with a Layered Double Hydroxide Modified Glassy Carbon Electrode as a Nanocatalyst

We report a simple and sensitive voltammetric sensor for the determination of chlorpromazine (CPZ) based on Ni?Al layered double hydroxide (NiAlLDH) modified glassy carbon electrode (GCE). NiAlLDH was simply electrodeposited on GCE surface in a very short time. The response linear range was 1×10^?3–1×10^?9 mol L^?1, with a detection limit of 1×10^?9 mol L^?1. The NiAlLDH film showed well defined and well separate peaks for dopamine, ascorbic acid, uric acid and CPZ in the same solution. The proposed electrode was used to measure the active pharmaceutical ingredient of CPZ tablet as a real sample.     

Synthesis and Release Behavior of a Hybrid of Camptothecin Intercalated Dodecyl Sulfate Modified Layered Double Hydroxide

The intercalation of a non-ionic and poorly water-soluble drug,camptothecin（CPT）,into dodecyl sulfate （DS） modified layered double hydroxide（LDH） was carried out via a secondary intercalation method to obtain a CPT-DS-LDH hybrid.The in vitro CPT release eFxaminations from the hybrid show that the hybrid can well control the release of CPT,which indicates that the hybrid is a potential drug controlled-release system.Moreover,the intercalation kinetics of CPT into the DS modified LDH fits for the pseudo-second-order model.And the release kinetic process of CPT from the CPT-DS-LDH hybrid at pH=4.8 can be described with pseudo-first-order model,while that at pH=7.2 can be described with both pseudo-first-order model and pseudo-second-order model.Meanwhile,the release mechanism of CPT from the CPT-DS-LDH hybrid was discussed.     

层状双金属氢氧化物/碳纳米管复合物的制备及在有机溶剂中的分散

通过硝酸处理在碳纳米管(CNTs)表面生成了羧基(-COOH)基团, 随后采用尿素法在其水悬浮液中原位合成了层状双金属氢氧化物(LDH), 获得了层状双金属氢氧化物/碳纳米管复合物(LDH/CNTs), 考察了CNTs用量对LDH形貌与结构的影响. 结果表明, CNTs的用量对LDH的产率及结构无显著影响; 但当CNTs用量较低(<0.2 g/L)或过高(>4.0 g/L)时, 会导致LDH的粒径分布变宽. 对LDH/CNTs进行氯化及有机化处理, 获得了十二烷基苯磺酸根离子(DBS)插层的DBS-LDH/CNTs. 对DBS-LDH/CNTs在不同有机溶剂中分散及剥离程度的研究发现, DBS-LDH/CNTs在丁醇、 乙醇及二甲苯中均可良好分散且其悬浮液较稳定, LDH在不同溶剂中的剥离程度为丁醇>乙醇>二甲苯>四氢呋喃.     

Using NMR in Structural Studies of Aluminum Hydroxide Intercalation Compounds with Lithium Salts

The effect of the anion charge on the structure of [LiAl₂(OH)₆]_nX (X = Cl^-, Br^-, I^-, SO₄ ^2-, C₆H₈O₄ ^2-) intercalation compounds and the water effect on the structure of [LiAl₂(OH)₆]Cl·nH₂O have been studied using ¹H, ⁷Li, and ²⁷Al NMR. A change in the charge on the anion leads to significant changes in the asymmetry parameter for the lithium and aluminum nuclei with relatively small changes in the quadrupolar coupling constant and the broadening factor. The structure of the intermediate [LiAl₂(OH)₆]Cl·0.5H₂O hydrate can be represented as a derivative of the structure of the anhydrous [LiAl₂(OH)₆]Cl intercalate with a slightly increased layer thickness and a minor orthorhombic distortion of the hexagonal cell; the water molecules partially fill the interlayer voids and participate in the diffusion process. Further hydration of the intercalate (x 1) leads to a minor (0.2) increase in the layer thickness and is accompanied by disordering of chloride ions and water molecules in the interlayer space.     

氟尿苷-层状双金属氢氧化物纳米杂化物制备及表征

采用共沉淀法将抗癌药物氟尿苷插入Mg-Al层状双金属氢氧化物(LDHs)的层间,合成了氟尿苷-LDHs纳米杂化物。依据氟尿苷分子大小和杂化物通道高度推测,氟尿苷分子是以长轴垂直或略倾斜于LDHs层片在LDHs层间呈双层排列。分别在pH=4.8和7.2的介质中研究了药物释放动力学,表明符合准二级动力学方程;释放速率随载药量增大而降低;氟尿苷-LDHs纳米杂化物具有良好的缓释效果。     

Intercalation of PM-19 into and in vitro Release of Anti-tumor Drug from Layered Double Hydroxide

Introduction Recently, controlled release of drugs and gene delivery technology have received considerable attention due to their numerous advantages including prolonged duration of action of an active agent, improved efficacy, reduced toxicity and convenience compared to the conventional dosage forms[1]. In this field typical systems are polymer delivery systems depending on the hydrolysis-induced degradation, swelling and erosion of carriers′ structures[1, 2], mesoporous silica carrier systems relying on capturing and releasing the CdS nanoparticles[3], and layered materials release systems based on ion-exchange principle[4].     

Mg-Al-NO_3层状双氢氧化物的制备及性能研究

制备了带正电荷的Mg-Al-NO_3层状双氢氧化物（LDH）,并对其组成、形貌、 电性能、离子交换性能等各种性质进行了表征。实验结果表明,所制备的正电纳米 颗粒具有可调控的层间自由空间。该方法为进一步研究聚合物/纳米复合材料提供 了一个合成前驱体的方法。     

Cauliflower‐like NiCo2O4−Zn/Al Layered Double Hydroxide Nanocomposite as an Efficient Electrochemical Sensing Platform for Selective Pyridoxine Detection

In the present study, a cauliflower‐like NiCo₂O₄?Zn/Al layered double hydroxide (NiCo₂O₄?Zn/Al LDH) nanocomposite was used as a novel electrode material for the sensitive and selective determination of pyridoxine (vitamin B₆). The structure and morphology of the as‐prepared nanocomposite were characterized by X‐ray diffraction (XRD), FT‐IR, field emission scanning electron microscopy (FESEM) and energy dispersive X‐ray spectroscopy (EDX). The NiCo₂O₄?Zn/Al LDH nanocomposite exhibited excellent electrocatalytic ability in the oxidation of pyridoxine, which could result from the synergistic effect of the two components. The developed sensor also provided a selective determination of pyridoxine in the presence of other species such as vitamins (B₁, B₂, B₁₂ and ascorbic acid), inorganic ions and biomolecules. The fabricated sensor showed a good linear response for pyridoxine over the concentration ranges 2×10^?7–2.0×10^?4 mol L^?1 with a low detection limit of 8.6×10^?8 mol L^?1. Finally, the proposed method was successfully applied for the determination of pyridoxine in commercial tablets and plasma samples with satisfactory results. Furthermore, this novel sensor displayed superior benefits in terms of stability, sensitivity, repeatability and cost. The present work aims to expand NiCo₂O₄ based nanocomposites to sensor fields and promote the development of pyridoxine sensors.     

Triton X-100六角液晶相中制备镁铝层状双金属氢氧化物纳米片及其药物载体应用

以Triton X-100 六角相溶致液晶作微反应器, 采用共沉淀法制备了镁铝层状双金属氢氧化物(LDHs)纳米薄片(L-LDHs). 以双氯芬酸钠(DS)为药物模型分子, 采用离子交换法制备了DS插层LDHs (DS/L-LDHs)纳米杂化物, 在37.0 ℃、pH=7.2的缓冲溶液中, 考察了纳米杂化物的药物释放性能, 并与传统溶液共沉淀法制备的镁铝LDHs (S-LDHs)纳米片状颗粒进行了对比. 采用粉末X射线衍射(XRD)、傅里叶变换红外(FT-IR)光谱、场发射扫描电镜(FE-SEM)、透射电镜(TEM)和N₂吸附-脱附等技术对所制备的LDHs和DS/LDHs 样品的晶体结构、比表面积、形貌特征等进行了表征. 结果表明, L-LDHs比S-LDHs具有更低的片厚度, 更高的比表面积和药物负载量, 所形成的DS/L-LDHs纳米杂化物药物释放速率也明显低于DS/S-LSHs, 即L-LDHs更适于作药物载体. DS/L-LDHs纳米杂化物的药物释放过程符合准二级动力学方程, 受颗粒内部扩散过程控制. 溶致液晶模板法可实现LDHs的形貌可控制备, 为LDHs基功能材料的研发提供了新途径.     

La~(3+)掺杂NiCo层状双金属氢氧化物纳米片的合成及其电化学性能

稀土离子La~(3+)掺杂的NiCo层状双金属氢氧化物纳米片具有高的超级电容器性能,比容量达到1115 F/g(1A/g)、倍率性能为517 F/g(30 A/g)。研究表明,La~(3+)离子掺杂不改变NiCo层状双金属氢氧化物晶体结构,但会显著影响其电子和离子传导特性,从而改变其电化学性能。根据离子电负性标度,La~(3+)(1.327)和Co~(2+)(1.377)离子的电负性值最接近,掺杂La~(3+)会优先取代Co~(2+)离子位置。由于La~(3+)离子的尺寸作用(106 pm),使得最优掺杂比例较小仅为0.26%,电化学结果表明较少的La~(3+)掺杂比例依然会显著调节NiCo层状双金属氢氧化物的电子/离子输运性质。