LDHs基柔性复合薄膜材料的研究进展:制备与功能化

层状双金属氢氧化物(LDHs)是一类典型的二维无机层状纳米材料,由于其具有层间可插入性、良好的各向异性及热稳定性等特点,已被广泛应用于药物负载与释放、功能助剂、吸附、催化、能量储存、光学等领域.LDHs粉体材料在使用过程中存在容易流失、易聚集、不利于实现器件化等缺点.因此,近年来,关于LDHs基薄膜材料的研究引起了人们的广泛关注.其中,LDHs基柔性复合薄膜由于其便携性、可延展性和良好的力学性能等优点,在电化学存储、光电子器件、气体阻隔材料等领域表现出广阔的应用前景.本文围绕LDHs基柔性复合薄膜材料的研究工作,重点介绍了其制备方法和功能化研究进展,并展望了今后可能的发展方向.     

层状双金属氢氧化物的剥离方法及其应用

层状双金属氢氧化物(LDHs)是由带结构正电荷的片层和层间阴离子有序组装而成的层状无机化合物, 近期其剥离研究受到关注. 剥离后的LDHs纳米片可被看做“无机高分子”, 具有纳米尺度的开放结构, 既可作为理论研究模型, 又可作为新型基元组装功能复合纳米结构或材料, 具有显著的应用潜力. 本文对LDHs的剥离方法、剥离产物的表征方法及其应用研究现状进行了综述, 并对今后的研究方向进行了展望.     

LDHs/碳复合纳米材料的催化性能研究进展

层状双金属氢氧化物(LDHs)是一类典型的结构可调的阴离子层状功能材料,直接或经焙烧、还原处理后可作为高活性、高稳定性、廉价的催化剂或催化剂载体应用到催化领域.碳纳米材料自身良好的力学、电学、化学性质使其可作为理想的功能组元构筑LDHs/碳复合纳米材料,进而增强催化性能.本文综述了由LDHs与碳材料构筑的复合纳米催化材料的设计、可控制备及其在电催化、光催化、催化加氢及氧化等多相催化领域的应用进展,并从材料的可控制备及应用方面讨论了LDHs/碳复合纳米材料在多相催化领域面临的挑战与发展前景.     

Fe3 O4@(TF-LDHs)纳米复合体的制备及药物缓释性能

采用共沉淀法, 以替加氟(Tegafur, TF)插层层状双金属氢氧化物(LDHs)纳米杂化物(TF-LDHs)包覆磁性基质Fe3O4, 得到了具有核/壳结构的纳米复合体[Fe3O4@(TF-LDHs)], 采用XRD, FTIR, TEM, VSM和元素分析等技术对样品的化学组成、 晶体结构\, 形貌及磁性等进行了表征, 探讨了药物分子在LDHs层间的存在状态, 考察了其药物释放行为. 结果表明, Fe3O4@(TF-LDHs)纳米复合体具有顺磁性, 其比饱和磁化强度随磁性基质含量的增大而增强; TF分子在LDHs层间以长轴略倾斜于LDHs层板的方式呈双层排布; Fe3O4@(TF-LDHs)纳米复合体具有明显的药物缓释性能, 其释放动力学过程符合准二级动力学方程, 颗粒内部扩散为释放过程的速率控制步骤.     

层状复合氢氧化物的有机改性方法及应用研究进展

层状复合氢氧化物(LDHs)因其化学组成可调、比表面积大、生物相容性好等特点,目前在环境、能源和生物医药等领域广受关注.然而, LDHs在合成过程中由于其分子内作用力易发生团聚而导致其在基体中的分散不均匀,极大地限制了LDHs在实际中的应用.有机改性是改善LDHs分散性的有效方法,从表面改性和插层改性两个方面综述了近年来LDHs的有机改性方法,并介绍了其在阻燃、吸附、催化、气体阻隔、发光、储能和生物医药材料等领域的应用.最后对改性后LDHs未来的研究方向和应用领域进行了展望.     

层状双金属氢氧化物在绿色材料领域中的应用

层状双金属氢氧化物(LDHs)由于其特殊的二维平面层状结构和良好的生物兼容性(低毒性),可以和不同材料杂化形成生态环境友好的纳米复合材料,广泛应用在生物分子的贮存、药物输送载体、有机催化、环境污染物的吸附去除以及光、电、磁等方面。本文介绍了LDHs的结构、制备、性能以及在绿色材料领域的应用研究进展,并对LDHs在绿色材料领域的发展方向进行了展望。     

基于LDHs荧光材料的组装及二维限域效应研究

近年来,层状双金属氢氧化物(LDHs)因其特殊的二维结构及限域环境,作为主体材料构筑了一系列性能优异的插层结构材料,在发光、成像、传感等领域显示了广泛的应用前景.本文从插层客体、组装方法及LDHs的二维限域效应等方面详细介绍了基于LDHs荧光材料的最新研究进展,讨论了二维限域效应与发光性能的内在关联,并探讨了LDHs材料在该领域面临的挑战和发展趋势.     

MgFe2O4@(TF-LDHs)磁性纳米复合体的制备与表征

以镁铁尖晶石(MgFe2O4)颗粒为磁性基质, 采用共沉淀法制备了替加氟(TF)插层层状双金属氢氧化物(LDHs)包覆MgFe2O4的核-壳结构磁性纳米复合体[MgFe2O4@(TF-LDHs)], 并对其化学组成、 晶体结构和磁性等进行了表征, 探讨了TF在LDHs层间的存在状态, 考察了TF的释放行为. 实验结果表明, MgFe2O4@(TF-LDHs)纳米复合体具有顺磁性, 其比饱和磁化强度随磁性基质含量的增大而增强; TF分子在LDHs层间以长轴略倾斜于LDHs层板的方式呈双层排布; MgFe2O4@(TF-LDHs)纳米复合体具有明显的药物缓释效果, 其释放动力学过程符合准二级动力学方程, 释放机理为Fick扩散; 增大磁性基质含量或施加外加磁场均可减缓其药物释放过程.     

层层组装法制备(LDH/DNA/LDH/LTO)_n多层复合膜及其红外辐射性能（英文）

采用层层自组装(LBL)的方式将带负电荷的层状氧化钛(LTO)纳米片以及DNA分子和带正电荷的层状双氢氧化物(LDH)纳米片交替组装,制备了一种人工设计的杂化薄膜,并研究了样品在8～14μm波段的红外发射率。X射线衍射(XRD)结果表明,(LDH/DNA/LDH/LTO)n杂化膜在垂直于基底的方向呈长程堆积的有序结构,DNA分子链和LTO纳米片均以单层的形式平铺在LDHs层板间。从扫描电子显微镜(SEM)和原子力显微镜(AFM)图像可以看出,薄膜呈现出均匀的、连续的表面形态。通过能量色散X射线光谱(EDS)和X射线光电子能谱(XPS)分析,确认了薄膜的组分,且每一种组分都均匀地平铺在每一个组装单层中,在垂直于基底的方向有序堆积形成均匀的薄膜。由于多组分之间存在协同作用,而且规整有序的层状薄膜结构的构筑增强了不同组分之间的界面效应、提供了平整光滑的薄膜表面,使该复合薄膜的红外发射率降低至0.419。这些结果清楚地表明,层层自组装方式制备的杂化复合膜能有效降低其红外发射率。     

层状复合金属氢氧化物：结构、性质及其应用

本文评述层状复合金属氢氧化物(layered double hydroxides，LDHs)的化学及其应用。层状复合金属氢氧化物具有结合紧密的氢氧化物层和处于层间的阴离子，其比较突出的化学性质是可逆的阴离子交换和热分解性质。不过，因为受到氢氧化物层的局限，处于层间的阴离子表现出的特殊化学性质近年来也越来越受到重视。利用上述三个方面的性质，人们发掘了层状复合金属氢氧化物在材料(包括有机无机复合材料)制备、离子交换与有害阴离子脱除、异构体化学分离、化学反应控制、阻燃材料、活性分子储存与缓释、局部化学反应合成、催化剂及催化剂载体等方面的应用。     

类水滑石材料主客体插层结构的构筑及特性的理论研究

因主体层板和层间客体具有丰富的可调性, 类水滑石材料(LDHs)在催化、 吸附、 生物医药及光、 电、 磁等方面展现出了广阔的应用前景. 近年来理论研究已成为揭示LDHs微观结构和性质的重要手段, 本文系统综述了LDHs材料主体结构、 客体结构以及主客体相互作用3个方面的理论研究工作进展, 及其在作为光驱动催化剂方面应用的理论研究. 从主体元素构成、 元素比例、 电荷分布、 拓扑结构转变、 能带结构、 态密度、 层间阴离子组成、 离子交换性能、 主客体作用力、 能量性质及光催化性能等方面, 在原子、 电子尺度上揭示了LDHs材料结构-性能之间的构效关系, 为以其为材料平台构筑一系列基于超分子插层结构主客体间相互作用的新型功能材料、 扩展材料的功能性提供了丰富的理论信息和有益指导.     

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.     

Electrosynthesis of hierarchical NiLa-layered double hydroxide electrode for efficient oxygen evolution reaction

Oxygen evolution reaction(OER) is a key process for electrochemical water splitting due to its intrinsic large overpotential. Recently, layered double hydroxides(LDHs), especially Ni Fe-LDH, have been regarded as highly performed electrocatalysts for OER in alkaline condition. Here we first present a new class of Ni La-LDH electrocatalyst synthesized by an electrochemical process for efficient water splitting. The as-prepared NiL a-LDH nanosheet arrays(NSAs) give remarkable electrochemical activity and durability under alkaline environments, with a low overpotential of 209 mV for OER to deliver a current density of 10 mA cm~(-2), surpassing most of previous reported LDHs eletrocatalysts. The presence of NiLa-LDH in this work extends the studies about LDHs-based electrocatalysts, which will benefit the development of electrochemical energy storage and conversion systems.     

Sensitive and selective fluorescence detection of guanosine nucleotides by nanoparticles conjugated with a naphthyridine receptor

Novel fluorescent nanosensors, based on a naphthyridine receptor, have been developed for the detection of guanosine nucleotides, and both their sensitivity and selectivity to various nucleotides were evaluated. The nanosensors were constructed from polystyrene nanoparticles functionalized by (N-(7-((3-aminophenyl)ethynyl)-1,8-naphthyridin-2-yl)acetamide) via carbodiimide ester activation. We show that this naphthyridine nanosensor binds guanosine nucleotides preferentially over adenine, cytosine, and thymidine nucleotides. Upon interaction with nucleotides, the fluorescence of the nanosensor is gradually quenched yielding Stern–Volmer constants in the range of 2.1 to 35.9 mM⁻¹. For all the studied quenchers, limits of detection (LOD) and tolerance levels for the nanosensors were also determined. The lowest (3σ) LOD was found for guanosine 3’,5’-cyclic monophosphate (cGMP) and it was as low as 150 ng/ml. In addition, we demonstrated that the spatial arrangement of bound analytes on the nanosensors’ surfaces is what is responsible for their selectivity to different guanosine nucleotides. We found a correlation between the changes of the fluorescence signal and the number of phosphate groups of a nucleotide. Results of molecular modeling and ζ-potential measurements confirm that the arrangement of analytes on the surface provides for the selectivity of the nanosensors. These fluorescent nanosensors have the potential to be applied in multi-analyte, array-based detection platforms, as well as in multiplexed microfluidic systems.     

On the Design of Fluorescent Ratiometric Nanosensors

Advances in nanoparticle technology have recently offered new tools to the bioanalytical field of research. In particular, new nanoparticle‐based sensors have appeared able to give quantitative information about different species (ions, metabolites, biomolecules) in biosamples through ratiometric measurements. This article describes the methodologies developed so far in the design of such nanosensors. In particular, the different approaches to immobilize fluorescent chemosensor dyes to nanoparticles are presented. Concept designs of ratiometric nanosensors in terms of composition and architecture are also described and illustrated with examples taken from the literature.     

Heterogeneous ultrathin films fabricated by alternate assembly of exfoliated layered double hydroxides and polyanion

Transparent heterogeneous ultrathin films of exfoliated layered double hydroxide (LDHs) nanosheets, fabricated alternately with polyanion, have been obtained via a layer-by-layer electrostatic self-assembly which yields a series of novel LDH films with potential multifunctionality.     

Study of assembly of arachidic acid/LDHs hybrid films containing photoactive dyes

Hybrid monolayers formed with an floating arachidic acid (AA) anions monolayer binding with a densely packed layered double hydroxides (LDHs) monolayer at an air/LDHs suspension interface has been studied by pi-A isotherms and TEM images. An ordered multilayer film of AA/LDHs has been fabricated by Langmuir-Blodgett technique on various substrates. The photoactive dyes (methyl orange, MO, and Congo red, CR) can be incorporated into the galleries of LDHs in the AA/LDHs hybrid LB film by an ion intercalation method. The results of FTIR and UV-vis absorption spectra can approve the formation of AA/LDHs/dyes composite films. In addition, UV-vis absorption spectra and LAXRD analyses also provide evidence for the good vertical uniformity and stable layered periodic structure of AA/LDHs/dyes films. More interestingly, it was found that the dye molecules intercalated can be induced by a positively charged LDHs sheet to align in a special orientation and form different aggregates: MO molecules form sandwich H-type aggregates, while CR molecules form head-to-tail J-type aggregates. On the basis of these data, a possible model of the AA/LDHs/dyes composite films was proposed. Also, the dye molecules incorporated into AA/LDHs films exhibit excellent configuration stability under the irradiation of UV light because the LDHs matrix offers a more rigid and constrained environment for them.     

Particle-particle interactions between layered double hydroxide nanoparticles

Changes in chemical properties of nanoscale particles include quantum size effect, changes in the cell parameters and lattice symmetry, and surface and interface effects. In the case of layered double hydroxides (LDHs), surface and interface effects dominate for nanoparticles of MgAl LDHs. Using TEM micrographs of nanoparticle-sized LDHs, we have found that the increased number of surface atoms relative to the internal atoms increases the surface-to-surface interparticle attractions. As a result, nanosize LDH particles are able to form continuous oriented films that adhere well to a polar substrate.     

Poly(decyl methacrylate)-based fluorescent PEBBLE swarm nanosensors for measuring dissolved oxygen in biosamples

150-250 nm Poly(decyl methacrylate)(PDMA) fluorescent ratiometric nanosensors for dissolved oxygen have been developed. Platinum octaethylporphine ketone (PtOEPK), the oxygen-sensitive dye, and octaethylporphyrin (OEP), the oxygen-insensitive dye, have been incorporated into PDMA nanoparticles to make the sensors ratiometric. Based on the corresponding Stern-Volmer plot, these nanosensors exhibit almost complete linearity over the whole range of dissolved molecular oxygen from 0 to 42.5 ppm (deoxygenated to pure oxygen-bubbled water). The overall quenching response is up to 97.5%, the best so far for all dissolved oxygen optical sensors. These PEBBLE nanosensors also show very good reversibility and stability to leaching and photobleaching, as well as very short response times and no perturbation by proteins. In human plasma they demonstrate a robust oxygen sensing capability, little affected by light scattering and autofluorescence. Potential applications include intracellular oxygen imaging and microresolved pressure profiles in biological and other heterogenous environments.     

Thin films of ��-Fe2O3 nanoparticles using as nonmetallic SERS-active nanosensors for submicromolar detection

A new kind of nonmetallic nanosensors based on surface-enhanced Raman spectroscopy (SERS) have been successfully prepared by the assembly of α-Fe₂O₃ nanoparticles (NPs) onto clean quartz surface via the cross-linker of hexamethylene diisocyanate (HDI). The resultant substrates have been characterized by electron micrographs, which show that the α-Fe₂O₃ NPs distribute on the modified surface uniformly with a monolayer or sub-monolayer structure. 4-mercaptopyridine (4-Mpy) and 2-mercaptobenzothiazole (2-MBT) molecules have been used as SERS probes to estimate the detection efficiency of the α-Fe₂O₃ thin films. The SERS experiments show that it is possible to record high quality SERS spectra from probe molecules on the α-Fe₂O₃ thin films at sub-micromolar ( < 10⁻⁶ mol/L) concentration. These results indicate that the highly ordered, uniformly roughed, highly sensitive and low-cost α-Fe₂O₃ thin films are excellent candidates for nonmetallic SERS-active nanosensors.