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2019 , Vol. 31 >Issue 2/3: 394 - 412

  DOI: https://doi.org/10.7536/PC180505

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文章编号: 2019020314  

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层状双氢氧化物（LDHs）的合成与应用

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收稿日期：2018-05-08

  要求修回日期：2018-07-09

  网络出版日期：2018-10-22

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Layered Double Hydroxides(LDHs): Synthesis & Applications

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  • 1. Department of Chemistry, University of Agriculture, Faisalabad 38000, Pakistan
  • 2. Department of Chemistry, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
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Received：8 May 2018

  rev-requestrev-request：9 Jul. 2018

  Online：22 Oct. 2018

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Saba Jamil , Afaaf Rahat Alvi , Shanza Rauf Khan , Muhammad Ramzan Saeed Ashraf Janjua . 层状双氢氧化物（LDHs）的合成与应用[J]. 化学进展, 2019 , 31(2/3) : 394 -412 . DOI: 10.7536/PC180505

Saba Jamil , Afaaf Rahat Alvi , Shanza Rauf Khan , Muhammad Ramzan Saeed Ashraf Janjua . Layered Double Hydroxides(LDHs): Synthesis & Applications[J]. Progress in Chemistry, 2019 , 31(2/3) : 394 -412 . DOI: 10.7536/PC180505

Abstract

Layered double hydroxides, a class of anionic clays possessing sandwich like structure in which negative anions are sandwiched into positively charged metal layers in a repeating manner, have been studied extensively. Layered double hydroxides could be fabricated with combination of different divalent(Cd2+, Mn2+, Fe2+, Pb2+) and trivalent(Al3+, Cr3+, Fe3+) metals and layered arrangement imparts unique properties such as adsorption properties and catalytic properties in these compounds. Exciting feature of these compounds is the memory effect. There are a number of methods to synthesize these layered compounds, such as co-precipitation, hydrothermal, sol-gel, urea hydrolysis, etc. The synthesized LDHs can be characterized morphologically and compositionally i.e. scanning electron microscopy, transmission electron microscopy, powder X-Ray diffraction, Mossbauer spectroscopy, thermogravimetric analysis, XPS, etc. The wonderful feature of layered double hydroxides is the pliancy of interlayer space enabling them to accommodate various anionic species, and high surface area making them efficient in numerous applications such as adsorbents, anion exchange, catalysts, and biological compatible.

Key words： layered double hydroxides(LDHs) ; application

Contents

1 Introduction
2 Structure
2.1 Composition
2.2 Delamination process
2.3 Calcination/memory effect/reconstruction
2.4 Pillared LDHs
3 Properties
3.1 Physical properties
3.2 Magnetic properties
4 Preparation methods
4.1 Co-precipitation method
4.2 Hydrothermal approach
4.3 Anion exchange process
4.4 Urea hydrolysis
4.5 Sol-gel method
5 Application
5.1 Adsorbents and anion exchangers
5.2 Catalysts, catalysts support and photocatalysts
5.3 Biological compatibility of LDHs
6 Future aspects
7 Conclusion

1 Introduction

Clays are commonly used minerals in Europe and Asia. They have been used as paper coatings, drilling muds, foundry moulds, adsorbents, catalysts, catalyst supports, ion exchangers, decolourizing agents, etc. Clays[1,2]are also important in agriculture, because many soils have large amount of clay minerals which determine soil properties such as water retention, fertility, structure and texture, etc.
In ancient times, clays were used as cosmetics, for treatment of many skin diseases(cicatrices), for therapeutic purposes(excipients), and to mark different symbols. Kaolinite and palygorskite had been used to protect gastric and intestinal mucous membrane, in the treatment of duodenal ulcers and as antidiarrhoeaics since prehistoric times. Clays remove water from faeces, resulting in more compact material because of their better adsorption capacity and high surface area[3,4].
The use of clays for cosmetic purposes is common in the world especially in the spas of Africa. Color of clays plays a key role in utilization, for example, cleansing of skin is performed by reddish clays, bacterial infection on skin is obviated by yellowish clays, bluish clay is effective in the prevention of acne, black and green colored clays are used for overall body nourishment and to control the amount of oil on skin, respectively[5,6,7].
But a limited number of clays(talc, kaolinite, palygorskite, sepiolite) are used because of technical and legal aspects, e.g. dissolution of Al is increased by ingestion of clay minerals which can cause serious issues[8]. Therefore, it is demanded to mention the intended utilization of clay minerals[9,10,11,12].
There are two well-known categories of clays, i.e. cationic clays and anionic clays. The former is extensively present in nature and consists of alumina silicate layers having negative charge while cations are present in interlayer region in order to balance the charge. Anionic clays are rare in nature, but simple and inexpensive to fabricate. Anionic clays contain layers of positively charged metal hydroxides with water molecules and anions in interlayer region. There are two building blocks of clay minerals tetrahedral Si(O/OH) and octahedral M(O/OH), M=(Al3+, Mg2+, Fe3+or Fe2+)[13,2]. Anionic clays are considered as natural or synthetic layered mixed hydroxides consisting of exchangeable anions in interstitial region. Depending upon composition, these compounds are given many names but generally used term is hydrotalcite type compounds and widely used name is layered double hydroxides[14,15].
Large scale researches have been conducted on hydrotalcite(Mg-Al hydroxycarbonate) because it is simple and economical to fabricate, therefore hydrotalcite name is given to LDHs. Feitknecht assumed a structure having intercalated hydroxide layers and named these compounds Doppelschichtstrukturen meaning double sheet structure. However, after many years single crystal X-ray diffraction analysis of these compounds rejected his assumptions. The XRD pattern showed that cations are located in layers while anions and water molecules in between the layers[16].

2 Structure

2.1 Composition

Chemical composition of layered double hydroxides is the exciting feature which defines their use in various applications and imparts phenomenal properties in these compounds. The general formula to describe the chemical composition is given as follow[17].
M 1 -x 2 + M x 3 + ( OH ) 2 · A x / n n - · m H 2 O
where M2+=divalent metal cation, M3+=trivalent metal cation, A=interlayer anion, n-=charge on anion, x and m are fraction constants, n=0 indicates that neutral layers are attracted by weak van der Waals forces and value of x lies in the range of 0.2~0.33. The structure of LDHs closely resembles brucite Mg(OH)2[18,2]. If value of x exceeds 0.33, large number of trivalent cations result in M(OH)3; and if x is below 0.2, divalent cations in brucite type sheets consisting of octahedra result in the precipitation of M(OH)2[19].
Fig.1 Schematic representation of LDH structure[20]
There is stacking of layers in LDH structure in which divalent and trivalent metals are present in the form of octahedral unit and anions between the layers. There exists divergence in the nature of intercalated anions and therefore there is narrow distribution in LDH composition. Trivalent metal ration decides charge density, i.e. x=M3+/(M2++M3+) and formula of representation is shrinked as [M2+-M3+-x]. M2+ and M3+ are generally taken from third and fourth period of periodic table, i.e. M2+: Mg, Mn, Fe, Co, Ni, Cu, Zn, M3+: Al, Mn, Fe, Co, Ni, Ga. Ionic radius ranges from 0.65~0.80 Å and 0.62~0.69 Å for divalent and trivalent cations, respectively, except for Al 0.50 Å[21].
Fig.2 Association of divalent and trivalent metallic cations in LDHs.(◆: monovalent- tetravalent)[22]
There is weak bonding between intercalated anions and host structure in these layered compounds. A number of anionic species can be intercalated between the layers during synthesis of layered structure. Intercalated anions[23] can belong to inorganic anions such as halides(F-, Cl-), oxo anions($\text{CO}_{3}^{2-}$, $\text{NO}_{3}^{-}$, $\text{SO}_{4}^{2-}$),(Mo7O24)6-,(V10O28)6- and organic anions, i.e. carboxylate, phosphates, alkyl sulfates, etc.

2.2 Delamination process

Delamination or exfoliation is a process in which layers of LDHs are peeled off into single or discrete sheets. After delamination process nanosheets of thickness 1~5 nm are obtained and it has remained a difficult task because of electrostatic interactions among layers[24].
Delamination process is influenced by the exchange of water molecules with incoming anions and completion time, usually twelve hours are required for Zn-Al delamination. The delamination process is summarized in Fig.3. It has been noticed that dispersion of dodecylsulfate in different solvents such as methane, hexane and ethanol results in variable colloidal suspension whereas stable translucent solutions are resulted in case of higher alcohols such as pentanol and hexanol[25].
Fig.3 Schematic illustration of the possible delamination mechanism for LDHs in formamide[30].
Polyacrylate was obtained from the monomers of acrylate which in turn are produced as a result of delamination process of Mg-Al layered double hydroxide[26]. Process of delamination was studied in different solvents such as butanol, toluene, CCl4, acrylates and formamide which were used as dispersant and dodecylsulfate as anionic surfactant[27]. The colloidal solutions of lactate containing LDHs delaminated in water were obtained[28]. Polymer layered double hydroxide nanocomposites were prepared from LDH sheets which were obtained by delamination of glycine-LDH in formamide[29].

2.3 Calcination/memory effect/reconstruction

Calcination is a process in which layered double hydroxides are treated at high temperatures and the layer stacking is disturbed as a result of this thermal treatment. Process of calcinations takes place in two steps:(1) water molecules are removed from surface shown in eq 1,(2) water molecules are removed from interlayer(dehydroxylation) followed by decomposition of layered structure eq 2.
M 1 -x 2 + M x 3 + (OH)2· A x / n n - ·mH2O→ M 1 -x 2 + M x 3 + (OH)2· A x / n n - (s)+mH2O(g)
M 1 -x 2 + M x 3 + (OH)2· A x / n n - (s)→ M 1 -x 2 + M x 3 + Ox(s)+mH2O(g)+CO2
M 1 -x 2 + M x 3 + Ox(s)→M2+O(s)+M2+ M x 3 + Ox
Intercalated anionic species decide the calcine temperature of LDH. After dehydroxylation, a mixed metal oxide is obtained with high specific surface area, improved basic properties, fine crystallites and stable towards thermal treatments. Mg-Al is studied widespread and MgO is obtained after calcinations. The reconstruction of original LDH structure is achieved by thermally treating calcined LDH with water or any other solvent[31,22,32].
Fig.4 Schematic representation of memory effect[33]
It is noticed that Mg-Al LDH loses its structure upon calcinations and after immersing in distilled water regains its structure, but some disorder in structure is observed. The anion exchange capacity of LDHs increases after calcinations and therefore their adsorption capacities are also increased than the corresponding uncalcined LDHs. Adsorption efficiency[34] is directly proportional to the amount of calcined LDHs(Fig.5). Calcined LDHs have proved to be efficient adsorbents in removal of indigo carmine dye[35], acid orange 10[36], and phosphate[37].
Fig.5 Adsorption of dicamba on calcined-LDH as functions of calcined-LDH concentration under a fixed dicamba concentration(1.36 mmol·dm-3)[34]
Number of patents has been increasing regarding calcined layered double hydroxides accommodating large organic molecules[38], polyoxometalate[39], terephtalate TP, benzene carboxylate BC, benzene sulfonate BS and benzene phosphonate BP[40], sebacic acid[41], and pentoses[42]. Calcined LDHs have been proved to be efficient sorbents for brilliant blue R(BBR). The calcined layered double hydroxides are utilized to detach pollutants of relatively high concentration and uncalcined LDH for low concentrations as shown below. It is noticed that amount of dye sorbed increased rapidly within three hours and became constant after nine hours for calcined LDHs while for uncalcined LDHs the amount of dye sorbed showed rapid increase within initial four hours and then uptake is slowed down in eighteen hours as shown in Fig.6 and Fig.7[43].
Fig.6 Effect of contact time on the uptake of Brilliant Blue R(BBR) by layered double hydroxides(LDHs) and calcined LDHs(CLDHs) at different initial concentrations[43]
Fig.7 Sorption isotherms for Brilliant Blue R(BBR) sorption by layered double hydroxides(LDHs) and calcined LDHs(CLDHs)[43]

2.4 Pillared LDHs

In the process of pillaring the layered structure is retained when an inorganic compound is modified into thermally stable meso and microporous material. There is a molecular distribution of layers in the interlayer region which makes these pillared compounds chemical and thermal stable. Pillared LDHs are extensively used for adsorptive and catalytic application because porosity and specific surface area of pillared materials are enhanced[44]. The main benefit of pillaring LDH is that interlayer space increases by intercalating large anions such as polyoxometalate(POMs), phthalocyanines, diphosphates[O3P-(C6H4)n-PO3]4-, [Fe(CN)6]3-, etc. Moreover, the catalytic activity of LDHs is enhanced as a result of pillar layer combination. Low M2+/M3+ ratio favors the synthesis of pillared layered double hydroxide in low pH region which is normally obtained by urea assisted co-precipitation method[45]. Polyoxometalates are widely studied pillaring agents consisting of multiple layered structure with space filling oxygen atoms and high charge densities. Polyoxometalates are acidic in nature and therefore impart acidic characteristics to layered double hydroxides[46]. Pillaring of LDH depends upon the swelling conditions of LDH and ion exchange ability. In the pillaring of LDH with POM leads to the partial dissolution of metals than their starting LDHs[47].
LDH swelling(limited to one or two layers) and their high layer charge density will not allow the penetration of organic reagents. However, anions are readily transferred to external edge surfaces for reaction with reagents adsorbed at those sites. Synthesis of Mg-Al layered double hydroxide has been studied pillared with metatungstate and found that by increasing the surface charge density of LDH the micropore diameter decreases[48]. Alkenes such as 2-hexene was selectively epoxidized by POM pillared LDH with H2O2 by having advantage that subsequent hydrolysis was suppressed to form diols compared to hydrotalcite free catalyst[49].
Layered double hydroxide pillared with decatungstate was used as catalyst in the epoxidation of alkenes with H2O2 to form peroxotungstate which assists epoxidation by transferring oxygen atom to alkenes. This type of catalytic oxidation is less favored for larger alkene than smaller alkenes[50]. Conversion of aliphatic and aromatic thiols into disulfides by Zn-Al layered double hydroxide intercalated with {MoO2[OOCC(S)(C6H5)2]2}2- anion was also studied[51]. A detailed mechanism is also reported for this type of conversion[52,53].
2R-S + 2LDH → 2R-S- + 2LDH-H+
2LDH-M2+ + O2 → 2LDH-M3+ + 2O2-
2R-S- + 2LDH-M3+ → 2R-S- + 2LDH-M2+
2R-S- → R-SS-R
O2- + 2LDH-H+ → 2LDH-H2O + 1/2 O2
Overall reaction is
2R-SH + 1/2 O2 → R-SS-R + H2O

3 Properties

3.1 Physical properties

Particle size, surface area, crystallinity, porosity and tensile strength are important physical characteristics that influence the applications of LDHs. These properties are dependent on methods of preparation used to synthesize these layered compounds. Scanning electron microscopy and transmission electron microscopy can be used to determine the morphology[45].
Crystallinity and pore size are important to describe catalytic and adsorptive properties of LDHs. Mass transfer process and regioselectivity are promoted by the uniformity of porous structure. Nitrogen adsorption process can be used to analyze porosity of a compound. Cajra et al studied textural properties of layered double hydroxide and concluded that pore size of LDHs lies in micro to mesoporous range. The microstructure is analyzed by both mesoporous and microporous characteristics[54].
Particle size is influenced by synthesis condition variables, i.e. time, temperature, pH and reaction stoichiometry. Small particle size and rough surface is obtained with variable pH, while larger particles are obtained in constant pH method showing sharp peak. SEM and TEM techniques can be used to determine the particle size[55].
Layered double hydroxides have high specific surface area of(100 ± 300) m2·g-1. High surface area facilitates guest host interactions. Larger crystallites synthesized by constant pH method exhibit lower surface area. Surface area of particle can be enhanced after calcination by transforming them into corresponding oxides or oxy hydroxides[56].
Tensile strength of these compounds decreases by increasing the concentration of LDH. However, a sharp decrease in elongation at break and steady increase in modulus was observed with increase in concentration of LDH. It is concluded that change tensile properties with concentration of LDH is due to the combined effect of compatibilizer and dispersed LDH particles[57].

3.2 Magnetic properties

The layers in LDHs are composed of metal cations with different oxidation states which can impart magentism in layers. The introduction of magnetic substrate into magnetic layers can lead to novel applications[58]. A new nano hybrid aspirin-LDH has been reported with magnetic properties and utilized efficiently in controlled drug delivery system[59]. Magnetic properties for Cu-Al LDH intercalated with carbonate and surfactants have been reported. Temperature dependent susceptibility plot χT vs T is shown in Fig. 8. At low temperature antiferromagnetic interactions are prominent while for CAS paramagnetic behavior is dominant because thermal agitation overcomes magnetic order[59].
Fig.8 Temperature dependent susceptibility plot χT vs T[59]
In Co-Al and Ni-Al hydrotalcite like compounds Co-Co and Ni-Ni ferromagnetic interactions are responsible for magnetic behaviour. Magnetic properties of calcined products appeared to be different from corresponding precursors but in this case consistent magnetism was obtained[60].
Fig.9 Schematic representation of spin frustration[62]
There are two main parameters which control the magnetism in LDHs. The first one is metal centers make in-layer magnetic superexchange via OH bridges and the second one is intense dipole interaction between individual layers. Spin frustration is a consequence of competing magnetic interactions and structural deformation. Ni-Cr layered double hydroxide shows spin frustration where Cr3+ is coupled antiferromagnetically to Ni2+ and spin of incoming Cr3+ is frustrated because it wants to be coupled antiferromagnetically to nearby Ni2+ and Cr3+ spins simultaneously. Spin frustration is shown below[61].

4 Preparatory methods

Miyata discloses in one of the fast patents which claim the synthesis of HTlcs[31] preparation of layered compounds where Mg2+, Ni2+ dications and Al3+ trications were combined with nitrate, chlorate and chlorides ions[64]. Many researchers have also contributed in the development of LDHs.
Although LDHs are easy to prepare but pure hydrotalcite like compounds are not easy to obtain. There are some points which are still vague such as relative amount of intercalated ion, range of cations, stacking arrangement and cation ordering in the layers. For preparation of pure LDHs, it is necessary to select the correct ratio of cation and anion. Countless methods are present in literature regarding synthesis of layered double hydroxides, e.g. co-precipitation, hydrothermal, solvothermal, topochemical synthesis, etc. In this review, five mostly utilized approaches are discussed, including(1) co-precipitation,(2) hydrothermal approach,(3) anion exchange method,(4) urea hydrolysis,(5) sol-gel method[31,65].
Table 1 Structural formula of some natural layered double hydroxides[63,21]
Mineral Structural Formula Intercalated ion Cell Parameters(Å) Space Group
Fougerite Fe42+Fe23+(OH)12[CO3]·3H2O OH-, Cl-, CO32- are possible a=3.17~3.18
c=22.7~22.9		 R$\bar{3}$m
Meixnerite [Mg6Al2(OH)16][(OH-)2.4H2O] OH- a=3.046 c=22.93 R$\bar{3}$m
Zincowoodwardite Zn1-xAlx(OH)2[SO4]x/2·nH2O
x<0.5, n<3x/2		 SO42- a=3.063 c=8.91 and
a=3.065 c=25.45		 P$\bar{3}$m and R$\bar{3}$m
Hydrotalcite [Mg6Al2(OH)16][(CO32-)·4H2O] CO32- a=6.13 c=46.15 R$\bar{3}$m
Pyroaurite [Mg6Fe3+(OH)16][(CO32-)·4H2O] CO32- a=6.19 c=46.54 R$\bar{3}$m
Mössbauerite Fe63+O4(OH)8[CO3]·3H2O CO32- a=3.07 c=22.25 R$\bar{3}$m
Charmarite Mn4Al2(OH)12[CO3]·3H2O CO32- a=10.98 c=15.10 P6322

4.1 Co-precipitation method

Co-precipitation method is commonly used procedure for preparing LDHs because it produces large amount of material and is easy to handle at laboratory level. In this procedure aqueous solutions of divalent and trivalent metals are used as precursors which contain intercalating anions. An interesting feature of this method is that there exists diversity in anionic species to intercalate in OH- sheets. Multiple cations can be precipitated by taking control over pH and supersaturation conditions. pH should be higher or equal to one at which most soluble hydroxide is precipitated[31,65].
Fig.10 Experimental device for the preparation of LDHs by the co-precipitation method[22]
Layered double hydroxides are prepared at high and low supersaturation conditions. Precipitation at low supersaturation requires slow addition of divalent and trivalent metals salt solution and pH is maintained at selected value. This method is performed to obtain high crystallinity and to obtain careful control of charge density of hydroxide layers.
On the other hand, co-precipitation at high supersaturation results in less crystallinity because of continual change in pH. Thermal treatment performed following co-precipitation may help increase the crystallinity of amorphous or badly crystallized materials[23]. Zn-Al LDH intercalating various amino acids have been prepared and found out that co-precipitation is maximum at pH 6~8 as zwitterion and as anion at pH 9~10 for phenylalanine[66]. Composites of tetra anion of perylene dye(PBITS) have been synthesized via co-precipitation at low supersaturation at pH=7.9. The PXRD pattern indicated that basal reflections 001 shift from 7.9 Å to 19.2 Å for Mg-Al LDH and 8.6 Å to 14.8 Å for Ca-Al LDH as shown in Fig. 11.
Fig.11 PXRD pattern for CaAl-LDH[67]
Fig.12 SEM micrograph of Ni-Ti-CO3 LDH(Ni/Ti=3)[68]
Fig.13 The SEM micrographs of the(a) ZnAl-4,(b) CZnAl-4-300 C and(c) CZnAl-4-500 C sample. The arrows in the left figures indicate where the enlargements(in the right figures) were taken. The marked spots(in the right figures) indicate the part taken for the EDX measurements[69]
Fig.14 SEM images of hydrotalcite samples hydrothermally treated at 160 and 180 ℃ for various times[71]

4.2 Hydrothermal approach

Post synthesis treatments are utilized to control the properties of LDHs. When an organic species having less affinity to LDH is needed to intercalate, anion exchange reactions and co-precipitation techniques are ineffective in this case. Hence hydrothermal synthesis has proven efficient because this method ensures no competing anion in the interlayer other than the intended by making insoluble hydroxides as inorganic source[70]. Hydrothermal approach is utilized to control particle size and its distribution. Ca-Al LDH has been prepared by hydrothermal synthesis and concluded that hydrothermal temperature affects the crystal structure of final product. A disordered structure is obtained at 100 ℃ and ordered at 120 ℃. It has been found that the main layers of both structures were similar and difference lies in the arrangement of interlayer anions and water molecules[65]. Hydrothermal approach is usually carried out to improve crystallinity and is studied for Mg-Al LDHs. It is found that increase in LDH crystal size results in improved crystallinity of hydrothermally treated samples. By increasing the Mg/Al ratio crystal size of LDH is observed to decrease[71,72]. Hydrothermal method involves reactions of metal oxides, customarily in aqueous solution, with the anion of interest. A general reaction is given below[73].
(1-x) M 2 + O +(x/2) M 2 3 + O3 +(x/n) A n - +(1 + x/2)H2O=[ M 1 -x 2 + M 3 + (OH)2] A x / n n - +(x) O H -
Hydrothermal treatment is post synthesis method and formation of MgAl LDHs from their oxides MgO has been reported. Three different viewpoints were presented for LDH formation:(1) during titration poorly crystallized LDHs were obtained,(2) Agglomerates first are amorphous then they form layered structure,(3) reconstruction of LDH structure from their calcined oxides[74]. Zhao et al successfully fabricated LDH nanorods via hydrothermal approach with excellent morphology at different pH. TEM images are shown in Fig. 15[75].
Fig.15 TEM images of NiAl LDH synthesized at different pH values.(a)5.5;(b)8.5;(c)10.0[75]

4.3 Anion exchange method

Anion exchange is the most effective technique to synthesize layered double hydroxide consisting of anions other than carbonates. LDHs have been synthesized containing variable anions by exchange of NO3-[31].Pillared materials consisting of bulky organic(sebacic acid) or inorganic(polyoxometalate, such as (V10O28)6- or(Mo7O24)6-) anions have been prepared. The order of intercalation is as follows:CO32-≫ SO42-≫ OH- ≫ F- ≫ Cl- ≫ Br- ≫ NO3-≫ I-[76,77]. Thermodynamic studies indicate that exchange of anion depends upon the interlayer arrangement of LDH[78]. Various anion exchange mechanisms of LDH have been reported. Anion exchange process has been fount efficient for the intercalation of organic anions[77,14,79]. The equation of anion exchange is shown as follows:
M 1 - x 2 + M x 3 + ( OH ) 2 A x / n n - · m H 2 O → M 1 -x 2 + M x 3 + ( OH ) 2 I A x / n n - · m H 2 O
IA=Intercalated Anion
The general representation for anion exchange is shown in Fig.16.
Fig.16 Anion exchange process[80]

4.4 Urea hydrolysis

Urea is placed in Brönsted bases with pKb=13.8 and highly soluble in water and by controlling the reaction temperature its hydrolysis rate can also be controlled. Urea hydrolysis first proceed via formation of ammonium cyanate(rate determining step) followed by formation of ammonium carbonate as fast step[22]:
CO(NH2)2 → NH4CNO
NH4CNO + 2H2O → 2NH4+ + CO32-
The urea method is an ideal way for the synthesis of hydrotalcite because both of the ions liberated by the urea hydrolysis, hydroxides and carbonates, are the main components of hydrotalcite. In typical synthesis salt solutions of divalent and trivalent metals are mixed with urea solution in a specific ratio and pH followed by hydrothermal treatment[81,82,83].
Fig.17 SEM micrographs of(A)unmodified LDH,(B)LDH-laurate,(C)LDH-SDS,(D)=LDH-SDBS; and(E)LDH-BEHP(the magnification bar indicates 2 μm length)[14]
Fig.18 Scanning electron micrographs of Mg-Al hydrotalcites synthesized by urea hydrolysis[83]
In order to control particle size distribution and growth, urea hydrolysis is carried out in water/EG medium in ration 1/4. Reaction temperature, amount of urea, M2+/M3+ molar ratios also play an important role in controlling particle growth[84]. Specific surface area and crystallinity are observed to increase by using urea[85,81,82].
Zn-Al LDH films have been successfully fabricated and applied as anticorrosion coatings, in optical devices and electrochemical applications. Utilizing urea or ammonia as a weak base leads to films with strong adhesion between the LDH and the substrate[81].

4.5 Sol-gel method

Sol-gel method has received attention of chemists due to its efficient route to induce remarkable properties into manmade materials[86,87,88].Zn-Al LDH films have been reported via sol-gel synthesis supported on paper, sponge and cloth and exhibited high adsorption capability and surface area[89]. Crystallinity of LDHs is affected by nature of precursor, time of aging, nature of acid used in hydrolysis in this process[90,91,92]. Ni-Al and Co-Al LDHs have been synthesized in poylol medium using acetate as precursor. Unlike co-precipitation, sol-gel method has the advantage of not necessitating pH or atmosphere control. It has been noticed that uniform pore size distribution and high specific surface area is obtained which contribute to catalytic properties of synthesized layered compounds[93]. Layered double hydroxides containing different combinations of Mg with Ga, In, and Al have been synthesized and observed that crystallinity is not much affected as in case of traditional methods. Figure 19 indicates that most of the pores fall in the range of meso size showing the increased surface area[94]. Sol-gel route is extended to synthesize multivalent LDHs and showed high thermal stability[95].
Fig.19 SEM image of [MgAl-CO3] product synthesized by the urea method in water/ethylene glycol(1/4)[84]
Fig.20 Pore size distribution of the uncalcined Mg/Al, Ga, in LDHs[94]
Fig.21 SEM images of the NiAl-LDH/paper film at(A) low magnification and(B) high magnification; the MgAl-LDH/paper film at(C) low magnification and(D) high magnification[89]
Fig.22 TEM images of sol-gel LDHs:(A) MgAl,(B) NiAl-A,(C) NiCoAl,(D) NiAl-N

5 Application

5.1 Adsorbents and anion exchangers

High anion exchange capacities and large surface area of layered double hydroxide make them excellent adsorbent for various organic and inorganic anions. Multiple molecules can be inserted in interlayer region of LDHs due to the flexibility of layers which helps in decontamination of water and participates in high anion exchange capacity making them preferable over conventional anion exchange resins. Targeted entity to be adsorbed may be of organic(phenols, aromatic carboxylic acids, dyes, pesticides, etc.) and inorganic(PO42-, SO42-, NO3-, CrO42-, F-, Cl-, Br-, I-, etc.) nature and a number of researches have been conducted to study the adsorption phenomenon of diverse species acting as contaminants in soil and water[65,56]. The pictorial representation for the adsorption process is given in Fig.23.
Fig.23 Adsorption of methylene orange on Mg/Al layered double hydroxide[107]
Petrochemical and petroleum industries produce many organic pollutants which produce annoying smell and phenols are one of them. Even at low concentrations phenols are harmful to organisms, therefore their removal from water is necessary. The phenomenal adsorption properties of layered double hydroxides make it easy to eliminate phenols from wastewater[108]. The OH- group of layered double hydroxide reacts with nitrogen and oxygen of methyl orange dye and hence removes it from wastewater[109].
Table 2 A brief literature of layered double hydroxide with different metal combinations
Metals-anion Preparation methods Charac. techniques ref
Ca-Al-NO3 Co-precipitation PXRD, FTIR 96
Co-Fe-OH
Co-Fe-OH/CO32- (pyroaurite group)		 Topochemical synthesis
Co-precipitation method		 XRD, SEM, TEM, AFM
XRD, FTIR, Mossbauer spectroscopy, DTA		 97
98
Co-La-CH3COO- hydrogen peroxide catalyzed hydrolysis reaction FTIR, PXRD, TGA, PL spectroscopy 99
Cu-Al- CO32- Hydrothermal approach FTIR, PXRD, TGA 100
Zn-Cr-Cl-/CO32-/NO3- Co-precipitation UV-VIS analysis, PXRD, FTIR 101, 102
Zn-Ti-NO3
Zn-Al-CO3
Zn-Al-CO32-/NO3-		 Co-precipitation
Co-precipitation
Co-precipitation at low supersaturation		 TEM, SEM, PXRD, XPS
SEM, TGA, PXRD, TEM
SEM, XRD, EDX, IR, TG/DTG		 103
56
104
Ni-Fe-Cl Topochemical synthesis SEM, TEM, PXRD, XPS, FTIR 105
Mn-Al-CO32-/NO3-/SO42-/Cl- Co-precipitation PXRD, FTIR, DTA/TG, SEM 106
NiTi-CO32- Co-precipitation at high supersaturation PXRD, SEM, ICP-AES, FTIR 68
Mg-Al-CO32- Hydrothermal approach
Urea hydrolysis		 SEM, XRD, TGA, FTIR
XRD, FTIR, BET		 71, 72,
84, 83
Zn-Al LDH films Urea hydrolysis
Sol-gel route		 XRD, SEM, TEM
XRD, SEM		 81
89
Ni-Al/Mg-Al-CO32- Sol-Gel method XRD, SEM, TEM, HRTEM 90
Zn-Al LDH Sol-gel method XRD, TG-DSC 91
Mg-Al/Ga/In Sol-gel method FTIR, XRD, DRIFT 94
Ni-Co-Al/Mg-Ni-Al Sol-gel method XRD, TEM, TGA-DTA 95
Pesticides(2,4-dinitrophenol, 2-methy-4,6-dinitrocresol) and herbicides(organophosphate and organophosphanate) were effectively adsorbed by considering memory effect and ion exchange ability of LDH[110]. Arsenic is considered to be carcinogenic and a major cause of pollutants. Researchers have devoted a lot of time to investigating that Mg-Al LDHs can act as efficient adsorbents for As and Se as well. Adsorption efficiency and selectivity of arsenate ion depend upon two factors, molar ration of Mg2+ and Al3+ and orientation of intercalating anion. It has been found that poorly crystalline layered hydroxides exhibit high adsorption capacity of As[111,112]. One of the hazardous pollutants of our ecosystem is 2,4-dichlorophenoxyacetic acid contaminating soil and water and therefore is needed to be removed by some economical and competent adsorbents, layered double hydroxide in this regard did not disappoint researchers and was efficiently exploited to remove this pollutant. As in the synthesized Mg-Al/NO3 LDH, nitrate ion shows less affinity to the LDH sheets and can be successfully replaced with contaminants[113].
Heavy metal cations, i.e. Ni2+, Co2+, Cu2+, Pb2+, Hg2+ and radioactive metals were eliminated by using chelate ligands intercalated LDH because of flexible interlamellar region and specific pH. The adsorption characteristics of metal cations were separately studied and concluded that metal cations were separated due to high bond energy and high sensitivity of OH of LDH[114,115]. Hydrotalcite mineral is a crucial alternative to Fe(OH)3 and therefore has ability to remove arsenic from aqueous solution[116,112].
Various uncalcined and calcined layered double hydroxides LDH of Mg-Al, Ni-Al and Zn-Cr have been used to investigate the adsorption of Cr4+ ion. Calcinations temperature, amount of M3+ in LDH precursor, pH of metal solution, calcinations time in removing dichromate ions by adsorption was determined. The aqueous solution of carbonate and chloride were used to release and adsorb dichromate ions on LDHs[117].
ZnCr-LDH was synthesized with different molar ratios of Zn and Cr and intercalated with nitrate anions in order to study uptake of fluoride. Chromium is one of the major pollutants of environment released from tannery and electroplating industries and therefore LDHs having Cr as trivalent cation are of great significance from environmental viewpoint[118].
Methylene blue, methyl orange and formaldehyde were removed successfully by using ZnCr and MgAl layered double hydroxides. Photocatalytic activity of ZnCr LDHs has been restricted because of low capability to separate electron hole pair, rapid charge recombination and band energy ranges from 2~3 eV. For the removal of formaldehyde, ZnCr LDH does not show photocatalytic activity[119].
A food dye sunset yellow FCF was removed from water by using CaAl LDH intercalated with nitrate and adsorption reached equilibrium in fifty minutes. It is observed that degree of dissociation of anionic dye and surface charge of adsorbents are affected by pH[120].
Surface area and pore volume were determined from the knowledge of degree of dispersion exhibited by these materials[121]. Layered double hydroxides have been used for CO2 capture at temperature from 200~400 ℃. CO2 adsorption ability of LDHs having nano spherical and sand rose morphology was compared[122]. Mixed metal oxides obtained after calcinations exhibit excellent basic properties and surface basicity of these oxides is determined by metal ratio. Adsorption of carbon dioxide for MgAl LDH was investigated at 200 ℃. It was observed that by increasing metal ratio from 1.5 to 3.5, CO2 capture capacity also increased then decreased when x is 4[123].
Methyl orange and Cr4+ are considered harmful pollutants for human beings as well as for aquatic animals. CoFe LDHs intercalated with nitrate ion were fabricated by conventional co-precipitation method at different molar ratios and proved efficient for the removal of these contaminants. It is concluded from structural analysis and adsorption isotherm that removal of these effluents take place in two steps:(1) adsorption from exterior surface,(2) exchange of anion from interlayer region[124]. Removal of dyes from wastewater is of significant consideration because dyes being colored pollutant cause environmental hazards. Phenomenal characteristics of LDHs such as large surface area, high anion exchange capacity and adaptable interstellar space make these compounds favorable to remove contaminants from aqueous systems. Adsorption efficiencies of calcined and uncalcined LDHs were compared and found that better removal efficiency is exhibited by calcined LDHs[125].
Various researches have been conducted to study the adsorption behavior of graphene and LDH composite and these nano hybrid showed remarkable adsorption capacities[126,127,128,129,130,131].
Nanocomposite of graphene and pure LDHs showed exponential increase in adsorption capacities. By using the process of delamination, adsorption capacities of LDHs were increased because of the particle size decreased. It has been investigated that adsorption capacities of MgAl LDHs were increased by 62% after addition of only 7% of graphene oxide[126].

5.2 Catalysts, catalyst support and photocatalysts

Flexible composition, synthesis ease(inexpensive or simple), eco-friendliness and high versatility makes LDH viable candidate in comparison to catalysts used conventionally. For determining LDHs base properties, comparison among zeolites and LDH Mg-Al as catalyst is made within condensation reaction. Condensation(Knoevenagel) is observed via using zeolites whereas with usage of LDH as catalyst reactions, such that Michael type addition and Claisen condensation can be observed. Within pKa range of 16.5 basic sites of material are shown[132]. Oxides of nitrogen and generation of soot from vehicles are considered as one main participant in human health and pollution. Catalyst derived from LDH Mg-Al has been utilized effectively in such respect which leads to NO oxidation into nitrogen dioxide(NO2) and for enhancing catalyst efficiency noble metal is used[133]. These catalysts are also used for studying basic and acidic behavior demonstrated via Prinetto et al. Various parameters of structure influence catalyst efficiency, i.e. trivalent and divalent cations ratio, interlamellar anions nature and conditions of preparation in turn effects characteristics of base and acid[134].
LDHs exciting feature is their catalyst utilization via reconstruction thus providing opportunity for their decoration into several anions. LDHs basic properties are induced via reconstruction which makes them efficient catalysts for use in different reactions being catalyzed, i.e. Claisen-schmidt and aldol condensation plus epoxidation. Catalysts supported with iron ease in ethyl-benzene degradation into styrene[135,136]. Excitation of ZnO and TiO2 via UV light are used widely as catalysts for reactive dyes degradation which requires many lamps of UV for purpose of photocatalysis. Pollutants degradation rate is not fast enough. Thus, the catalyst’s role is limited by these factors. An advantage is induced by LDH for their utilization as catalyst via LDH Mg-Al and ZnO nano-composite synthesis in Acid Red G degradation[137]. LDH Mg-Al is therefore known as active UV photocatalyst with no response towards visible light and utilized successfully in generation of hydrogen photocatalytically[138].
LDHs of Zn-Cu-Fe-Al-Mn with Al/Fe/Mn/Zn/Cu possessing atomic ratios variably within synthetic mixture prepared via co-precipitation under controlled pH and temperature conditions. Precursor’s decomposition generated mixed oxides in air at 500 ℃. Characterization was done using various techniques such that TG-DTA-MS, TG-DTA, TEM, FT-IR, ICP-ES, XRD, H2-TPR and O2-TPD. Main objective is investigation of Fe and Mn partial substitution effect in to Al-Zn-Cu MMO derived from precursor LDH on catalytic, chemical and physical properties. Results indicated that substitution of manganese and iron decreased LDHs structure stability and improvement of LDHs calcined redox properties. The phenol oxidation with wet H2O2 catalytic activity is proportional to metal ions surface content and main centers of Cu2+ linked to lattice oxygen surface and deep oxidation degree if it’s related mainly to surface bonded weak oxygen reactivity which depends upon transition metallic ion’s nature within structure. Phenol per-oxidation via ·OH surface radical with origin from H2O2 helps in favoring next oxidation deeply[139].
Techniques of photocatalysis using metallic semi-conductors i.e. SnO2, ZnO, CdS, SnO2 applied widely for organic pollutant’s degradation in aqueous solutions. LDHs Al/Zn with different ratios of cations prepared through co-precipitation used conventionally at cons. pH. Improvement in photocatalytic activity is observed upon sample’s calcinations at 500 ℃ owing to large ZnO phase amounts formation[104].
LDH hybrid materials of La/Cr/Zn synthesized with excellent photo-catalytic activity. TiO2 photo-catalysts can’t be activated via visible light owing to larger band gap which generates low efficiency of electronic-photo conversion. Photocatalysts based on LDH emerged as potential candidate for replacing titanium dioxide due to novel layer structure, band gaps which can be tunable, easy scaling up and good activity of photocatalysis for splitting of water and related reactions[140].
Nano-composites containing titanium have prepared via Ti-Ni LDH calcinations used as precursor. Evaluation of titanium based nano-composite possesses excellent activity of photocatalysis under irradiation of visible-UV. Methylene blue degradation is observed via such nano-composites. Photocatalysis process relies on hole/electron pairs generation via radiation of band gap giving rise to reactions i.e. redox with species absorbance upon catalysts surface. Thus, it is necessary that particles of nano-composites from LDH of Ti-Ni(calcined) show property of photocatalysis under irradiation of both ultra-voilet and visible owing to their high areas of surface and absorption properties(in Vis-UV)[141].
Attention is being paid to LDHs for their utilization ads photocatalytic material attributed to its specific microstructure, adjustable band gap(forbidden) and properties of recyclable. Bi-metallic oxide can be formed when calcinated under highest temperature with highest dispersion of second metal and doping into materials of LDH where such materials photocatalysis can be improved dramatically[142].
Catalysts(semiconducting/basic bi-functional) synthesized via simple eco-friendly method afterwards incorporation of cerium oxide is done for purpose of degradation photo-catalytically of chlorinated and simple phenolic compounds. Photocatalysis efficiency is attributed to effect like self-sensitizing which occurs while dye adsorption to surface of CeO2.Support of ceria on Mg-Fe-Al LDHs and Mg-Al which are calcined have studies as catalysts with potency of sulfur oxides removal because of their properties of redox/basic[143].
In current work, advantage of LDH materials memory effect, fabrication of doped LDH surface supported with TiO2 was described possessing highest dispersibility. Ti4+,Al3+, Cu2+, and Mg2+ possessing LDH prepared via co-precipitation[144].
LDH of Zn/Fe with various intercalation anions(carbonate, chloride) and anion in terms of photocatalysts fabricated via method of co-precipitation. Methyl violet decolourization plus malachite green was performed photocatalytically. Principally, photocatalyst photo absorption depends upon hole-electron pairs mobility which evaluated electrons probability and holes for reaching photocatalyst surface reaction sites[145]. Chemical composition and synthesis conditions decide basic properties of LDHs. MgAl-LDH after calcination at 623 K was converted to MgAlO which possess large number of basic site[16]. In materials based on LDH, activation treatments and composition chemically determines basic property. For maintaining basic function, whatever may be content of metals within samples of Mg(Al)O/Pd, introduction of palladium was done via impregnation of Pd acetylacetonate in toluene solution which is free of water[146].
Catalytically active oxides exhibiting acid base behavior are prepared from layered double hydroxides which have high specific surface area. An important reagent extensively used in paint industry and in dewaxing of mineral oil methyl isobutyl ketone is prepared by acetone hydrogenation over NiAlO catalyst. It is reported that hydrotalcite type compounds are useful to convert acetone into methyl isobutyl ketone and methyl isobutyl carbinol[147].

5.3 Biological compatibility of LDHs

Layered double hydroxides have been utilized in various biological applications due to their limber interlayer region. Different anions such as aspartate, glutamate and salicylate are inserted LDHs for drug support against stomach irradiations[148]. Mg-Al LDHs as biocompatible are widely studied in literature. DNA was intercalated into layered double hydroxides by following encoding, encrypting, decrypting and decoding and proved advantageous for rapid analysis and stability in encrypting[149].
Various layered double hydroxides(MgAl, MnAl, NiAl, ZnAl, and ZnCr) have been prepared by co-precipitation method intercalating amino acids using phenylalanine[150,151]. Polyoxometalate are common pillaring agents for LDHs and heptamolybdate- and decavanadate-pillared hydrotalcite-type clays have also been fabricated. Organic anions consisting of aromatic rings are best substitute of polyoxometalate because layers of LDHs are separated to large extent[152].
5.3.1 Drug delivery applications
LDH after intercalation of citrate anion are studied to be beneficial as antacid and for drug delivery applications because those anions possessing greater affinity to layers are more stable to acid attack[153]. Riopan and Rioplus(both provide relief to sour stomach) have been proven efficient adsorbents for indomethacin(non-steroidal anti-inflammatory drug). Artificial membranes can be affected by this sort of adsorption[154].
In a biocompatible layered hosts, a drug remain reserved and protected from oxygenated and photo reactions. Because of the excellent anion exchange characteristics of layered double hydroxides, a drug may release after commanding interstellar compounds. The drug release rate depends upon the deintercalation rate. Aspirin was intercalated in Mg-Al LDHs and observed that rate of decomposition of aspirin is increased in Mg-Al layered double hydroxides[155].
A non-essential amino acid named L-Tyrosine(4-hydroxyphenylalanine) is fabricated within human body from phenylalanine and is used in providing relief from stress plus in the treatment of dementia. Because layered double hydroxides are effective as a matrix for controlled release of drug delivery system. Therefore, NiAl, MgAl and ZnAl LDHs intercalated with L-Tyr were synthesized[156]. Mg-Al LDH intercalated with prednisone-cholate ion has been synthesized by co-precipitation method. In order to study the release kinetics of prednisone from LDH, four kinetic models(i.e. first-order equation, Higuchi equation, Bhaskas equation and Ritger-Peppas equation) were selected and it was concluded that Ritger-Peppas equation described this procedure satisfactorily based on a directing excel based solver[157].
5.3.2 Biosensors
In order to resolve environmental and health issues, electrochemical biosensors have attracted the attention of scientists. Adsorption of enzyme was carried out on Zn-Al-Cl LDH to prepare electrochemical biosensor for determination of phenol based on deactivation of polyphenol oxidase[158]. For the accurate measurement of urea in urine or blood sample to treat kidney and liver diseases, biosensors are used. These biosensors are based on enzyme urease which catalyzes urea into hydrogenocarbonate and ammonium as expressed in equation below. For this purpose Mg-Al LDH/urease biosensors were fabricated[159].
(NH2)2CO + 2H2O + H+ →2N H 4 + + HC O 3 -
Glucose is of great importance in food chemistry, clinical chemistry, environmental chemistry and biochemistry, therefore its estimation is necessary to determine. A composite of chitosan and NiAl LDH nanoflakes is used to determine glucose[160]. DNA-LDH nanohybrid was synthesized successfully after intercalation of DNA into Mg-Al LDH via anion exchange process. Layered double hydroxide after intercalation of enzymes has been utilized as biosensors[161]. Polypyrrole-LDH composite was prepared in order to construct glucose/oxygen biofuel cell[151]. Large DNA fragments were inserted into LDH layers vis co-precipitation method and has been utilized in biological applications to carry out small oligonucleotides, plasmid DNA encoding genes for therapeutic purposes[162,163].

6 Future Aspects

LDHs have attracted attention because of their potential applications in industry. LDH host matrices to store biologically important species is the area of intense research. Numerous bioactive entities comprise carboxylic acids and hence intercalated into LDHs. Isomeric guest ion mixture is also separated by LDHs recently, e.g. equimolar mixture of 1,2-,1,3- and 1,4-benzenedicarboxylate was reacted with LiAl2Cl and noted that 1,4-BDC showed 100% selectivity while other anions remain in solution[164].
Reconstruction of LDHs is an exceptional feature which increases the demand of these layered compounds. Important structural evolution and phase changes occur when LDHs are treated at higher temperatures. LDHs have been found to have potential adsorbent capacities for SOx but a limited number of researches have been reported so far. In future they will replace conventional adsorbents on industrial scale[165].
It has been investigated that calcined LDHs show higher binding ability with cement matrix than their uncalcined precursor. Chloride ions in cement cause phase transition by ion exchange or adsorption process and hence affect the binding of cement, therefore chloride ions need to be removed from cement. LDHs can be used to perform this action[166].
Various health and environmental issues are created due to the presence of NOx such as acid rain formation, regional haze and increasing concentration of ozone. Therefore concentration of NOx needs to be controlled for daily life as well as industrial processes. Number of researches are present in literature for NOx sensors based on metal oxides but these sensors require high temperature in order to have considerable sensitivity. LDHs solve this issue and provide a sensor at room temperature due to their large surface area and flexible interlayer region[167]. It is clear that in near future layered double hydroxides will be used on large scale because they possess remarkable properties which decide their applications in various fields.

7 Conclusion

In this present review the structural aspects, common preparation methods, properties and important applications of various layered double hydroxide are summarized briefly. The exciting feature of these lamellar compounds is their composition which enables them to be utilized in multiple fields. The primary factors that play a role in the size and crystallinity of LDH particles are the methods through which they synthesized. Due to their potentially attractive properties, these compounds have replaced many conventional adsorbents and catalysts. This review studies the adsorption and catalytic applications for various layered double hydroxide containing different metal cations. By increasing the particle size of adsorbent, rate of adsorption decreases and particle size increases by thermally treating layered double hydroxides[109]. Mobility, solubility of dyes and equilibrium capacity can be influenced by temperature. Surface charge of LDHs, dissociation of functional groups and solubility of some dyes are affected by pH of solution. Furthermore, fascinating properties are observed in these compounds by modifying them after introducing ligands. The main objective of modification aims to enlarge their adsorption properties.

参考文献

原文顺序 | 文献年度倒序 | 文中引用次数倒序
[1]
Dong X, Jing Q, Shi Y, Yang Z, Pan S, Poeppelmeier K R, Young J, Rondinelli J M . J. Am. Chem. Soc., 2015,137:9417. https://www.ncbi.nlm.nih.gov/pubmed/26147880

DOI: 10.1021/jacs.5b05406   PMID: 26147880

本文引用 [1] 摘要

Pb(II) has long been associated with lone pair activity and is often substituted in alkali earth metal borates to create new nonlinear optical (NLO) materials with enhanced second harmonic generation (SHG) capabilities. However, large enhancement in isomorphic Pb-free analogues is rare. Here we report a new NLO material Pb2Ba3(BO3)3Cl with a phase-matching SHG response approximately 3.2× that of KDP and 6× higher than its isomorphic compound Ba5(BO3)3Cl. We show that the enhanced SHG response originates from a unique edge-sharing connection between lead-oxygen polyhedra and boron-oxygen groups, making the dielectric susceptibility more easily affected by the external electric field of an incident photon. This understanding provides a route to identify systems that would benefit from SHG-active cation substitution in isomorphic structures that exhibit weak or null SHG responses.
[2]
Vaccari A . Catal. Today, 1998,41:53.
本文引用 [3]
[3]
Carretero M, Gomes C, Tateo F . Develop. Clay Sci., 2006,1:717.
本文引用 [1]
[4]
Wu H, Pan S, Poeppelmeier K R, Li H, Jia D, Chen Z, Fan X, Yang Y, Rondinelli J M, Luo H . J. Am. Chem. Soc., 2011,133:7786. https://www.ncbi.nlm.nih.gov/pubmed/21534555

DOI: 10.1021/ja111083x   PMID: 21534555

本文引用 [1] 摘要

Introduction of the Cl(-) anion in the borate systems generates a new perovskite-like phase, K(3)B(6)O(10)Cl, which exhibits a large second harmonic response, about four times that of KH(2)PO(4) (KDP), and is transparent from the deep UV (180 nm) to middle-IR region. K(3)B(6)O(10)Cl crystallizes in the noncentrosymmetric and rhombohedral space group R3m. The structure consists of the A-site hexaborate [B(6)O(10)] groups and the BX(3) Cl-centered octahedral [ClK(6)] groups linked together through vertices to form the perovskite framework represented by ABX(3).
[5]
Matike D, Ekosse G, Ngole V . Intl. J. Phys. Sci., 2011,6:7557.
本文引用 [1]
[6]
Shi G, Wang Y, Zhang F, Zhang B, Yang Z, Hou X, Pan S, Poeppelmeier K R . J. Am. Chem. Soc., 2017,139:10645. https://www.ncbi.nlm.nih.gov/pubmed/28726399

DOI: 10.1021/jacs.7b05943   PMID: 28726399

本文引用 [1] 摘要

2BO3F2 (KBBF) is a unique nonlinear optical material for generation of deep-ultraviolet coherent light; however, its industrial application is limited. Here, we report a new material NH4B4O6F, which exhibits a wide deep-ultraviolet transparent range and suitable birefringence that enables frequency doubling below 200 nm. NH4B4O6F possesses large nonlinear coefficients about 2.5 times that of KBBF. In addition, it is easy to grow bulk crystals and does not contain toxic elements.]]>
[7]
Wu H, Yu H, Yang Z, Hou X, Su X, Pan S, Poeppelmeier K R, Rondinelli J M . J. Am. Chem. Soc., 2013,135:4215. https://www.ncbi.nlm.nih.gov/pubmed/23448539

DOI: 10.1021/ja400500m   PMID: 23448539

本文引用 [1] 摘要

The generation of intense coherent deep-UV light from nonlinear optical materials is crucial to applications ranging from semiconductor photolithography and laser micromachining to photochemical synthesis. However, few materials with large second harmonic generation (SHG) and a short UV-cutoff edge are effective down to 200 nm. A notable exception is KBe2BO3F2, which is obtained from a solid-state reaction of highly toxic beryllium oxide powders. We designed and synthesized a benign polar material, Ba4B11O20F, that satisfies these requirements and exhibits the largest SHG response in known borates containing neither lone-pair-active anions nor second-order Jahn-Teller-active transition metals. We developed a microscopic model to explain the enhancement, which is unexpected on the basis of conventional anionic group theory arguments. Crystal engineering of atomic displacements along the polar axis, which are difficult to attribute to or identify within unique anionic moieties, and greater cation polarizabilities are critical to the design of next-generation SHG materials.
[8]
Wang Y, Zhang B, Yang Z, Pan S . Angew. Chem., 2018,130:2172. https://www.ncbi.nlm.nih.gov/pubmed/18220399

DOI: 10.1021/ja710665q   PMID: 18220399

本文引用 [1]
[9]
López-Galindo A, Viseras C, Cerezo P . Appl. Clay Sci., 2007,36:51.
本文引用 [1]
[10]
Tateo F, Summa V, Bonelli C, Bentivenga G . Appl. Clay Sci., 2001,20:97.
本文引用 [1]
[11]
Wang X, Wang Y, Zhang B, Zhang F, Yang Z, Pan S . Angew. Chem., 2017,129:14307.
本文引用 [1]
[12]
Zhang B, Shi G, Yang Z, Zhang F, Pan S . Angew. Chem. Int. Ed., 2017,56:3916. https://www.ncbi.nlm.nih.gov/pubmed/28251767

DOI: 10.1002/anie.201700540   PMID: 28251767

本文引用 [1] 摘要

2 BO3 F2 suffers high toxicity through beryllium and strong layered growth. Herein, we propose a beryllium-free material design and synthesis strategy for DUV NLO materials. Introducing the (BO3 F)4- , (BO2 F2 )3- , and (BOF3 )2- groups in borates could break through the fixed 3D B-O network that would produce a larger birefringence without layering and simultaneously keep a short cutoff edge down to DUV. The theoretical and experimental studies on a series of fluorooxoborates confirm this strategy. Li2 B6 O9 F2 is identified as a DUV NLO material with a large second harmonic generation efficiency (0.9×KDP) and a large predicted birefringence (0.07) without layering. This study provides a feasible way to break down the DUV wall for NLO materials.]]>
[13]
Rajamathi M, Thomas G S, Kamath P V . J. Chem. Sci., 2001,113:671.
本文引用 [1]
[14]
Costa F R, Leuteritz A, Wagenknecht U, Jehnichen D, Haeussler L, Heinrich G . Appl. Clay Sci., 2008,38:153.
本文引用 [3]
[15]
Yu H, Wu H, Pan S, Yang Z, Su X, Zhang F . J. Mater. Chem., 2012,22:9665.
本文引用 [1]
[16]
Del Hoyo C . Appl. Clay Sci., 2007,36:103.
本文引用 [2]
[17]
Nalawade P, Aware B, Kadam V, Hirlekar R . Amsterdam:Elsevier, 2009,64.
本文引用 [1]
[18]
Li S, Bai H, Wang J, Jing X, Liu Q, Zhang M, Chen R, Liu L, JiÅ C . Chem. Eng. J., 2012,193:372.
本文引用 [1]
[19]
Mishra G, Dash B, Pandey S . Appl. Clay Sci., 2018,153:172.
本文引用 [1]
[20]
Hashim N, Sharif S N, Hussein M Z, Isa I M, Kamari A, Mohamed A, Ali N M, Bakar S A, Mamat M . Mater. Res. Innov., 2017,21:129.
本文引用 [1]
[21]
Trolard F, Bourrié G . London: InTech., 2012,60.
本文引用 [2]
[22]
De Roy A, Forano C, Besse J . United States: Nova Science, 2001,1.
本文引用 [4]
[23]
De Roy A . Mol. Crys. Liq. Crys., 1998,311:173.
本文引用 [1]
[24]
Antonyraj C, Koilraj P, Srinivasan K . United States: Nova Science, 2012,1.
本文引用 [1]
[25]
Leroux F, Adachi-Pagano M, Intissar M, Chauvière S, Forano C, Besse J P . United States: Nova Science, 2001,1.
本文引用 [1]
[26]
O’Leary S, O’Hare D, Seeley G . Chem. Commun., 2002: 1506.
本文引用 [1]
[27]
Wang Q O’Hare D . Chem. Rev., 2012,112:4124. https://www.ncbi.nlm.nih.gov/pubmed/22452296

DOI: 10.1021/cr200434v   PMID: 22452296

本文引用 [1]
[28]
Hibino T, Kobayashi M . J. Mater. Chem., 2005,15:653.
本文引用 [1]
[29]
Hibino T . Chem. Mater., 2004,16:5482.
本文引用 [1]
[30]
Liu Z, Ma R, Osada M, Iyi N, Ebina Y, Takada K, Sasaki T . J. Am. Chem. Soc., 2006,128:4872. https://www.ncbi.nlm.nih.gov/pubmed/16594724

DOI: 10.1021/ja0584471   PMID: 16594724

本文引用 [1] 摘要

This paper describes a systematic study on the synthesis, anion exchange, and delamination of Co-Al layered double hydroxide (LDH), with the aim of achieving fabrication and clarifying the properties of LDH nanosheet/polyanion composite films. Co-Al-CO3 LDH hexagonal platelets of 4 mum in lateral size were synthesized by the urea method under optimized reaction conditions. The as-prepared CO3(2-)-LDH was converted to Cl- -LDH by treating with a NaCl-HCl mixed solution, retaining its high crystallinity and hexagonal platelike morphology. LDHs intercalated with a variety of anions (such as NO3-, ClO4-, acetate, lactate, dodecyl sulfate, and oleate) were further prepared from Cl- -LDH via an anion-exchange process employing corresponding salts. Exchanged products in various anion forms were found to show different delamination behaviors in formamide. Among them, best results were observed for NO3- -LDH in terms of the exfoliating degree and the quality of the exfoliated nanosheets. The delamination gave a pink transparent suspension containing well-defined nanosheets with lateral sizes of up to 2 microm. The resulting nanosheets were assembled layer-by-layer with an anionic polymer, poly(sodium styrene 4-sulfonate) (PSS), onto quartz glass substrates to produce composite films. Magnetic circular dichroism (MCD) measurements revealed that the assembled multilayer films exhibited an interesting magneto-optical response.
[31]
Cavani F, Trifiro F, Vaccari A . Catal. Today, 1991,11:173.
本文引用 [5]
[32]
Valente J S, Lima E, Toledo-Antonio J A, Cortes-Jacome M A, Lartundo-Rojas L, Montiel R, Prince J . J. Phys. Chem. C, 2010,114:2089.
本文引用 [1]
[33]
Forano C, Costantino U, Prévot V, Gueho C T . Amsterdam: Elsevier, 2012,1.
本文引用 [1]
[34]
You Y, ZhÅ H, Vance G F . Appl. Clay Sci., 2002,21:217.
本文引用 [2]
[35]
El Gaini L, Lakraimi M, Sebbar E, Meghea A, Bakasse M . J. Hazard. Mater., 2009,161:627. https://www.ncbi.nlm.nih.gov/pubmed/18573613

DOI: 10.1016/j.jhazmat.2008.04.089   PMID: 18573613

本文引用 [1] 摘要

Layered double hydroxides (LDHs) calcined, denoted as CLDHs, have been shown to recover their original layered structure in the presence of appropriate anions. In the light of this so-called &amp;quot;memory effect&amp;quot;, the removal of indigo carmine (IC), an anionic dye, from aqueous solution by calcined Mg-Al-CO(3) LDHs was investigated in batch mode. We looked at the influence of pH values, dye-adsorbent contact time, initial dye concentration and various temperatures of heating of LDHs on the decolorization rate of IC. The adsorption isotherms, described by Freundlich model are L-type. The characterization of the solids CLDHs, both fresh and after removal of IC, by X-ray diffraction and infrared spectroscopy shows that the IC adsorption on CLDHs is enhanced by reconstruction of a matrix hydrotalcite intercaled by the dye, and the intercalation of the organic ion was clearly evidenced by the net increase in the basal spacing from 0.76 nm for [Mg-Al-CO(3)] to 2.13 nm for the organic derivative.
[36]
Extremera R, Pavlovic I, Pérez M, Barriga C . Chem. Eng. J., 2012,213:392.
本文引用 [1]
[37]
Cheng X, Huang X, Wang X, Sun D . J. Hazard. Mater., 2010,177:516. https://www.ncbi.nlm.nih.gov/pubmed/20060217

DOI: 10.1016/j.jhazmat.2009.12.063   PMID: 20060217

本文引用 [1] 摘要

The influence of calcination of Zn-Al layered double hydroxides (LDHs) on their phosphate adsorption capacity was studied in order to improve phosphorus removal from an excess sludge liquor. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), thermogravimetry-differential scanning calorimetry (TG-DSC) and nitrogen adsorption-desorption were employed to characterize the raw Zn-Al and the calcined products. The results reveal that the Zn-Al LDHs evolved to a phase of mixed metal oxides with the calcination temperature increasing to 300 degrees C and finally to spinel ZnAl(2)O(4) at 600 degrees C. When the Zn-Al was calcined at 300 degrees C, the interlayer carbonate ions were removed and the greatest BET surface area of 81.20 m(2)/g was achieved. The tested phosphate adsorption capacities of the raw and calcined Zn-Al were closely related to the evolution of physicochemical properties of the LDHs during the calcination. The Zn-Al-300 (Zn-Al LDHs calcined at 300 degrees C) exhibited the highest P uptake of 41.26 mg P/g in 24h. The phosphate adsorption by the raw Zn-Al and the Zn-Al-300 both follows a pseudo-second-order kinetic model; the adsorption isotherms show a good fit with a Langmuir-type equation.
[38]
Laguna H, Loera S, Ibarra I A, Lima E, Vera M A, Lara V . Micropor. Mesopor. Mater., 2007,98:234.
本文引用 [1]
[39]
Chibwe K, Jones W . Chem. Mater., 1989,1:489.
本文引用 [1]
[40]
Prévot V, Forano C, Besse J P . Appl. Clay. Sci., 2001,18:3.
本文引用 [1]
[41]
Chibwe K, Jones W . Chem. Commun., 1989,926.
本文引用 [1]
[42]
Aisawa S, Hirahara H, Ishiyama K, Ogasawara W, Umetsu Y, Narita E . J. Solid State Chem., 2003,174:342.
本文引用 [1]
[43]
Zhu M X, Li Y P, Xie M, Xin H Z . J. Hazard. Mater., 2005,120:163. https://www.ncbi.nlm.nih.gov/pubmed/15811678

DOI: 10.1016/j.jhazmat.2004.12.029   PMID: 15811678

本文引用 [3] 摘要

Layered double hydroxides (LDHs) with a Mg/Al molar ratio of 2:1 were synthesized by using a co-precipitation method and their calcined products (CLDHs) were obtained by heating Mg/Al-LDHs at 500 degrees C. Sorption of a weak acid dye, Brilliant Blue R (BBR), by LDHs and CLDHs indicated equilibrium time required for BBR sorption by CLDHs was less than 12h, regardless of initial concentration of BBR, whereas BBR sorption by LDHs was longer than 20 h. Sorption capacity of CLDHs was much larger than that of LDHs. Therefore, CLDHs could be used to remove anionic dyes of relatively high concentrations while LDHs may only be used to remove anionic dyes of low concentrations. Isotherms for BBR sorption by CLDHs and LDHs were well described using the Freundlich and Langmuir equations, respectively. When the initial pH of BBR solutions was lower than 8.0, the final pH of the solution after sorption was enhanced and stabilized at 10.6-10.8. The effect of initial pH (&amp;lt;8.0) on BBR removal was negligible, which would be environmentally important for precipitation/co-precipitation of co-existing metal cations. The effects of both Cl- and SO4(2-) on BBR sorption by CLDHs were minimal; but the presence of CO(3)2- markedly reduced BBR removal. Thermal regeneration for re-use of LDHs and CLDHs after BBR sorption was feasible only within the first two cycles, after which the regenerated materials suffered from a large loss in their sorption capacities.
[44]
Auerbach S M, Carrado K A, Dutta P K. . United States: CRC Press. 2004,1.
本文引用 [1]
[45]
Wang J D, Serrette G, Tian Y, Clearfield A . Appl. Clay. Sci., 1995,10:103.
本文引用 [2]
[46]
Kwon T, Tsigdinos G A, Pinnavaia T J . J. Am. Chem. Soc., 1988,110:3653.
本文引用 [1]
[47]
Wang J, Tian Y, Wang R C, Clearfield A . Chem. Mater., 1992,4:1276.
本文引用 [1]
[48]
Weir M R, Kydd R A . Micropor. Mesopor. Mater., 1998,20:339.
本文引用 [1]
[49]
Tatsumi T, Yamamoto K, Tajima H, Tominaga H O . Chem. Lett., 1992,21:815.
本文引用 [1]
[50]
Tatsumi T, Tajima H, Yamamoto K, Tominaga H . Amsterdam: Elsevier, 1993,1.
本文引用 [1]
[51]
Corma A, Fornes V, Rey F, Cervilla A, Llopis E, Ribera A . J. Catal., 1995,152:237.
本文引用 [1]
[52]
Braterman P, Xu Z, Yarberry F . Amsterdam: Elsevier, 2004,1
本文引用 [1]
[53]
Tichit D, Fajula F . Amsterdam: Elsevier, 1999,1
本文引用 [1]
[54]
Carja G, Nakamura R, Aida T, Niiyama H . Micropor. Mesopor. Mater., 2001,47:275.
本文引用 [1]
[55]
Yun S K, Pinnavaia T J . Chem. Mater., 1995,7:348.
本文引用 [1]
[56]
Rives V . United States: Nova Publishers, 2001,1.
本文引用 [2]
[57]
Costa F, Satapathy B, Wagenknecht U, Weidisch R, Heinrich G . Eur. Polym. J., 2006,42:2140.
[58]
Wang J, You J, Li Z, Yang P, Jing X, Zhang M . Nanoscale Res. Lett., 2008,3:338.
本文引用 [1]
[59]
Carja G, Chiriac H, Lupu N . J. Mag. Magn. Mater., 2007,311:26.
本文引用 [3]
[60]
Pérez-Ramírez J, Ribera A, Kapteijn F, Coronado E, Gómez-García C J . J. Mater. Chem., 2002,12:2370.
本文引用 [1]
[61]
Milanovic N . Amsterdam: Elsevier, 2016,1
本文引用 [1]
[62]
Almansa J J, Coronado E, Martí-Gastaldo C, Ribera A . European J. Inorgan. Chem., 2008,2008:5642.
本文引用 [1]
[63]
Mills S, Christy A, Génin J M, Kameda T, Colombo F . Mineral. Mag., 2012,76:1289.
本文引用 [1]
[64]
Miyata S . Clays. Clay Miner., 1975,23:369.
本文引用 [1]
[65]
Duan X, Evans D G . United States: Springer, 2009,1.
本文引用 [4]
[66]
Aisawa S, Takahashi S, Ogasawara W, Umetsu Y, Narita E . Clay Sci., 2000,11:317.
本文引用 [1]
[67]
Bauer J, Behrens P, Speckbacher M, Langhals H . Adv. Func. Mater., 2003,13:241.
本文引用 [1]
[68]
Zhang W, Guo X, He J, Qian Z . J. European Ceram. Soc., 2008,28:1623.
本文引用 [1]
[69]
Seftel E, Popovici E, Mertens M, De Witte K, Van Tendeloo G, Cool P, Vansant E . Micropor. Mesopor. Mater., 2008,113:296.
本文引用 [1]
[70]
Ogawa M, Asai S . Chem. Mater., 2000,12:3253.
本文引用 [1]
[71]
Kovanda F, Koloušek D, Cílová Z, Hulínský V . Appl. Clay Sci., 2005,28:101.
本文引用 [2]
[72]
Sharma S K, Kushwaha P K, Srivastava V K, Bhatt S D, Jasra R V . Indus. Eng. Chem. Res., 2007,46:4856.
本文引用 [1]
[73]
Bravo-Suárez J J, Páez-Mozo E A, Oyama S T . Quimica Nova, 2004,27:601.
本文引用 [1]
[74]
Xu Z P, Lu G Q . Chem. Mater., 2005,17:1055.
本文引用 [1]
[75]
Zhao Y, Xiao F, Jiao Q . J. Nanotechnol., 2011,646409.
本文引用 [2]
[76]
Carlino S . Solid State Ion., 1997,98:73.
本文引用 [1]
[77]
Choy J H, Choi S J, Oh J M, Park T . Appl. Clay Sci., 2007,36:122.
本文引用 [2]
[78]
Israëli Y, Taviot-Guého C, Besse J P, Morel J P, Morel-Desrosiers N . Dalton Trans., 2000,791.
本文引用 [1]
[79]
Costantino U, Nocchetti M, Sisani M, Vivani R . Int. J. Mater. 2009,224:273.
本文引用 [1]
[80]
Bullo Saifullah M Z B H . Intl. J. Nanomed., 2015,10:5609.
本文引用 [1]
[81]
Guo X, Zhang F, Evans D G, Duan X . Chem. Commun., 2010,46:5197. https://www.ncbi.nlm.nih.gov/pubmed/20549015

DOI: 10.1039/c0cc00313a   PMID: 20549015

本文引用 [3] 摘要

Layered double hydroxide (LDH) films have been widely investigated in the last few years because of their promising applications in areas such as catalysis, anti-corrosion coatings for metals, and as components in optical, electrical, and magnetic devices. In this Feature Article we review recent work, from our own laboratory and elsewhere, on the synthesis, properties and applications of functional LDH films, and also offer some perspectives for the design of future multifunctional LDH films.
[82]
Han Y, Liu Z H, Yang Z, Wang Z, Tang X, Wang T, Fan L, Ooi K . Chem. Mater., 2007,20:360.
本文引用 [2]
[83]
Ogawa M, Kaiho H . Langmuir, 2002,18:4240.
本文引用 [2]
[84]
Adachi-Pagano M, Forano C, Besse J P . J. Mater. Chem., 2003,13:1988.
本文引用 [2]
[85]
Benito P, Herrero M, Barriga C, Labajos F, Rives V . Inorg. Chem., 2008,47:5453. https://www.ncbi.nlm.nih.gov/pubmed/18494464

DOI: 10.1021/ic7023023   PMID: 18494464

本文引用 [1] 摘要

The use of urea as a precipitating agent in the synthesis of Ni-Al and Zn-Al layered double hydroxides having a hydrotalcite-like structure via a microwave-hydrothermal method is reported. For comparison purposes, the samples were also prepared by a conventional hydrothermal method. Ni-Al compounds with the hydrotalcite-like structure were obtained in shorter periods of time by the microwave method than by the conventional method, whereas when zinc cations were involved, no successful synthesis was achieved regardless of the method used. In order to find the best synthesis conditions for the Ni-Al solids, samples were submitted to microwave-hydrothermal treatment at different temperatures for increasing periods of time, and the structural, thermal, and textural properties of the synthesized materials were evaluated. All of the solids were fully characterized by chemical elemental analysis, powder X-ray diffraction (PXRD), FT-IR spectroscopy, and transmission and scanning electron microscopy as well as by N 2 adsorption/desorption at -196 degrees C for assessment of specific surface area and porosity. The PXRD patterns showed that the layered structure appeared after merely 10 min when the synthesis was carried out at 125 degrees C; however, the FT-IR spectra showed the presence of some cyanate groups that were formed during urea hydrolysis and were quite difficult to remove completely. When the conventional hydrothermal treatment was used, longer periods of time were required in order to develop the hydrotalcite-like structure, but increasing the aging time improved the crystallinity of the compounds and yielded large particles.
[86]
Dunn B, Zink J I . J. Am. Chem. Soc., 2007,122:11834
本文引用 [1]
[87]
Huang J, Kunitake T . J. Am. Chem. Soc., 2003,125:11834. https://www.ncbi.nlm.nih.gov/pubmed/14505402

DOI: 10.1021/ja037419k   PMID: 14505402

本文引用 [1] 摘要

Surface sol-gel process was used to replicate the hierarchical morphology of natural cellulosic substances with nanometer precision. The resultant artificial fossils are ceramic nanomaterials composed of metal oxide nanotubes.
[88]
Weatherspoon M R, Cai Y, Crne M, Srinivasarao M, Sandhage K H . Angew. Chem. Intl. Ed., 2008,47:7921. https://www.ncbi.nlm.nih.gov/pubmed/18773402

DOI: 10.1002/anie.200801311   PMID: 18773402

本文引用 [1]
[89]
Zhao Y, He S, Wei M, Evans D G, Duan X . Chem. Commun., 2010,46:3031. https://www.ncbi.nlm.nih.gov/pubmed/20386858

DOI: 10.1039/b926906a   PMID: 20386858

本文引用 [2] 摘要

Layered double hydroxides (LDHs) films with hierarchical morphologies have been fabricated on different templates via the sol-gel nanocopying and in situ growth process, which exhibit desirable mechanical properties and high adaptability in water treatment.
[90]
Prinetto F, Ghiotti G, Graffin P, Tichit D . Micropor. Mesopor. Mater., 2000,39:229.
本文引用 [1]
[91]
Tichit D, Lorret O, Coq B, Prinetto F, Ghiotti G . Micropor. Mesopor. Mater., 2005,80:213.
本文引用 [1]
[92]
Tokumoto M S, Pulcinelli S H, Santilli C V, Briois V . J. Phys. Chem. B, 2003,107:568.
本文引用 [1]
[93]
Prevot V, Forano C, Besse J . Chem. Mater., 2005,17:6695.
本文引用 [1]
[94]
Aramendıa M A, Borau V, Jiménez C, Marinas J M, Ruiz J R, Urbano F J . J. Solid State Chem., 2002,168:156.
本文引用 [2]
[95]
Prince J, Montoya A, Ferrat G, Valente J S . Chem. Mater., 2009,21:5826.
本文引用 [1]
[96]
Rojas R . Appl. Clay Sci., 2014,87:254.
[97]
Ma R, Liu Z, Takada K, Iyi N, Bando Y, Sasaki T . J. Am. Chem. Soc., 2007,129:5257. https://www.ncbi.nlm.nih.gov/pubmed/17394321

DOI: 10.1021/ja0693035   PMID: 17394321

摘要

This paper describes a topochemical synthetic approach to Co2+-Fe3+ layered double hydroxides (LDHs). Micrometer-sized hexagonal platelets of brucite-like Co2/3Fe1/3(OH)2 were first prepared by a homogeneous precipitation of an aqueous solution of divalent cobalt and ferrous ions through hexamethylenetetramine (HMT) hydrolysis under a nitrogen gas atmosphere. A subsequent oxidative intercalation process, by the action of iodine (I2) in chloroform (CHCl3), transformed the precursory brucite-like Co2+-Fe2+ hydroxides into hydrotalcite-like Co2+-Fe3+ LDHs, in which the oxidization of Fe2+ into Fe3+ induced positive charges to the octahedral hydroxyl layers while anions (I-) were intercalated into the interlayer space. Co2+-Fe3+ LDHs inherited the high crystallinity and hexagonal platelet morphology from their brucite-like precursor due to the topotactic nature of the transformation, which was verified by abundant microscopic and spectroscopic characterizations. After a normal ion-exchange process, Co2+-Fe3+ LDHs accommodating perchlorate anions were exfoliated into unilamellar nanosheets in formamide by an ultrasonic treatment.
[98]
Hansen H C B, Koch C B, Taylor R M . J. Solid State Chem., 1994,113:46.
[99]
Meenakshi P, Sitharaman U, Rajamani N . J. Rare Earths, 2017,35:474.
[100]
Britto S, Kamath P V . J. Solid State Chem., 2009,182:1193.
[101]
Delgado R R, Vidaurre M A, de Pauli C, Ulibarri M, Avena M . J. Colloid Interf. Sci., 2004,280:431.
[102]
Hirata N, Tadanaga K, Tatsumisago M . Mater. Res. Bull., 2015,62:1.
[103]
Shao M, Han J, Wei M, Evans D G, Duan X . Chem. Eng. J., 2011,168:519.
[104]
Seftel E, Popovici E, Mertens M, de Witte K, van Tendeloo G, Cool P, Vansant E . Micropor. Mesopor. Mater, 2008,113:296.
本文引用 [1]
[105]
Li Y, Li H, Yang M, He X, Ni P, Kang L, Liu Z H . Appl. Clay Sci., 2011,52:51.
[106]
Aisawa S, Hirahara H, Uchiyama H, Takahashi S, Narita E . J. Solid State Chem., 2002,167:152. https://linkinghub.elsevier.com/retrieve/pii/S0022459602996374

DOI: 10.1006/jssc.2002.9637

[107]
Yao W, Yu S, Wang J, Zou Y, Lu S, Ai Y, Alharbi N S, Alsaedi A, Hayat T, Wang X . Chem. Eng. J., 2017,307:476.
本文引用 [1]
[108]
Ulibarri M, Pavlovic I, Hermosin M, Cornejo J . Appl. Clay Sci., 1995,10:131.
本文引用 [1]
[109]
Ulibarri M, Pavlovic I, Barriga C, Hermosın M, Cornejo J . Appl. Clay Sci., 2001,18:17.
本文引用 [2]
[110]
Chaara D, Pavlovic I, Bruna F, Ulibarri M, Draoui K, Barriga C . Appl. Clay Sci., 2010,50:292.
本文引用 [1]
[111]
Wang S L, Liu C H, Wang M K, Chuang Y H, Chiang P N . Appl. Clay Sci., 2009,43:79.
本文引用 [1]
[112]
Yang L, Shahrivari Z, Liu P K, Sahimi M, Tsotsis T T . Indus. Eng. Chem. Res., 2005,44:6804. https://pubs.acs.org/doi/10.1021/ie049060u

DOI: 10.1021/ie049060u

本文引用 [2]
[113]
Chao Y F, Chen P C, Wang S L . Appl. Clay Sci., 2008,40:193. https://linkinghub.elsevier.com/retrieve/pii/S0169131707001585

DOI: 10.1016/j.clay.2007.09.003

本文引用 [1]
[114]
Li S S, Jiang M, Jiang T J, Liu J H, Guo Z, Huang X J . J. Hazard. Mater., 2017,338:1. https://www.ncbi.nlm.nih.gov/pubmed/28531655

DOI: 10.1016/j.jhazmat.2017.05.017   PMID: 28531655

本文引用 [1] 摘要

-1 over the range from 0.03 to 1.0μM under the optimized conditions. Otherwise, the selectivity, anti-interference, stability measurements and practical implications of Fe/Mg/Ni-LDH modified GCE are also performed. What,s more, a reasonable mechanism of detection for Pb(II) including selectivity and sensitivity is proposed based on adsorption and characterized using XPS and XRD. These findings provide a potentially excellent material to improve the sensitivity and selectivity for toxic metal ions as well as a deep understanding of detection.]]>
[115]
Pshinko G . J. Chem., 2013,2013.
本文引用 [1]
[116]
Ardau C, Frau F, Nieddu G, Fanfani L . Water Mining Environ., 2007,385.
本文引用 [1]
[117]
Goswamee R L, Sengupta P, Bhattacharyya K G, Dutta D K . Appl. Clay Sci., 1998,13:21.
本文引用 [1]
[118]
Koilraj P, Kannan S . Chem. Eng. J., 2013,234:406.
本文引用 [1]
[119]
Liu X, Zhao X, Zhu Y, Zhang F . Appl. Catal. B Environ., 2013,140:241.
本文引用 [1]
[120]
De Sá F P, Cunha B N, Nunes L M . Chem. Eng. J., 2013,215:122.
本文引用 [1]
[121]
Wang Q, O’Hare D . Chem. Commun., 2013,49:6301. https://www.ncbi.nlm.nih.gov/pubmed/23739826

DOI: 10.1039/c3cc42918k   PMID: 23739826

本文引用 [1] 摘要

A facile method for the synthesis of Zn2Al-borate and Mg3Al-borate layered double hydroxides (LDHs) with extremely high specific surface areas of 458.6 and 263 m(2) g(-1) and containing delaminated nanosheets is reported. To the best of our knowledge, this is the first report of LDH powders that still remain exfoliated on drying.
[122]
Wang Q, Gao Y, Luo J, Zhong Z, Borgna A, Guo Z, O’Hare D . RSC Adv., 2013,3:3414.
本文引用 [1]
[123]
Gao Y, Zhang Z, Wu J, Yi X, Zheng A, Umar A, O’Hare D, Wang Q . J. Mater. Chem. A, 2013,1:12782.
本文引用 [1]
[124]
Ling F, Fang L, Lu Y, Gao J, Wu F, Zhou M, Hu B . Micropor. Mesopor. Mater., 2016,234:230.
本文引用 [1]
[125]
Yang Z, Wang F, Zhang C, Zeng G, Tan X, Yu Z, Zhong Y, Wang H, Cui F . RSC Adv., 2016,6:79415.
本文引用 [1]
[126]
Daud M, Kamal M S, Shehzad F, Al-Harthi M A . Carbon, 2016,104:241.
本文引用 [2]
[127]
Fang Q, Chen B . J. Mater. Chem. A, 2014,2:8941.
本文引用 [1]
[128]
Tan L, Wang Y, Liu Q, Wang J, Jing X, Liu L, Liu J, Song D . Chem. Eng. J., 2015,259:752.
本文引用 [1]
[129]
Wen T, Wu X, Tan X, Wang X, Xu A . ACS Appl. Interf. Sci., 2013,5:3304.
本文引用 [1]
[130]
Yuan X, Wang Y, Wang J, Zhou C, Tang Q, Rao X . Chem. Eng. J., 2013,221:204. https://linkinghub.elsevier.com/retrieve/pii/S1385894713001368

DOI: 10.1016/j.cej.2013.01.090

本文引用 [1]
[131]
Zhang F, Song Y, Song S, Zhang R, Hou W . ACS Appl. Interf. Sci., 2015,7:7251.
本文引用 [1]
[132]
Corma A, Fornes V, Martin-Aranda R, Rey F . J. Catal., 1992,134:58.
本文引用 [1]
[133]
Yang R, Gao Y, Wang J, Wang Q . Dalton Trans., 2014,43:10317. http://xlink.rsc.org/?DOI=c3dt52896k

DOI: 10.1039/c3dt52896k

本文引用 [1]
[134]
Prinetto F, Ghiotti G, Durand R, Tichit D . J. Phys. Chem. B, 2000,104:11117. https://pubs.acs.org/doi/10.1021/jp002715u

DOI: 10.1021/jp002715u

本文引用 [1]
[135]
Di Cosimo J, Dıez V, Xu M, Iglesia E, Apesteguıa C . J. Catal., 1998,178:499. https://linkinghub.elsevier.com/retrieve/pii/S0021951798921613

DOI: 10.1006/jcat.1998.2161

本文引用 [1]
[136]
Takehira K . Appl. Clay Sci., 2017,136:112. https://linkinghub.elsevier.com/retrieve/pii/S0169131716305117

DOI: 10.1016/j.clay.2016.11.012

本文引用 [1]
[137]
Yuan S, Li Y, Zhang Q, Wang H . Colloid. Surf. A, 2009,348:76. https://linkinghub.elsevier.com/retrieve/pii/S0927775709004063

DOI: 10.1016/j.colsurfa.2009.06.040

本文引用 [1]
[138]
Parida K, Satpathy M, Mohapatra L . J. Mater. Chem., 2012,22:7350. http://xlink.rsc.org/?DOI=c2jm15658j

DOI: 10.1039/c2jm15658j

本文引用 [1]
[139]
Zhang L, Li F, Evans D, Duan X . Indus. Eng. Chem. Res., 2010,49:5959. https://pubs.acs.org/doi/10.1021/ie9019193

DOI: 10.1021/ie9019193

本文引用 [1]
[140]
Dinari M, Momeni M M, Ghayeb Y . J. Mater. Sci., 2016,27:9861.
本文引用 [1]
[141]
Shu X, He J, Chen D, Wang Y . J. Phys. Chem. C, 2008,112:4151. https://pubs.acs.org/doi/10.1021/jp711091m

DOI: 10.1021/jp711091m

本文引用 [1]
[142]
Zhang L, Xiong Z, Zhao G . Amsterdam: Elsevier, 2015,1.
本文引用 [1]
[143]
Valente J S, Tzompantzi F, Prince J . Appl. Catal. B Environ., 2011,102:276. https://linkinghub.elsevier.com/retrieve/pii/S0926337310005400

DOI: 10.1016/j.apcatb.2010.12.009

本文引用 [1]
[144]
Lu R, Xu X, Chang J, Zhu Y, Xu S, Zhang F . Appl. Catal. B Environ., 2012,111:389.
本文引用 [1]
[145]
Parida K, Mohapatra L . Chem. Eng. J., 2012,179:131. https://linkinghub.elsevier.com/retrieve/pii/S138589471101309X

DOI: 10.1016/j.cej.2011.10.070

本文引用 [1]
[146]
Das N, Tichit D, Durand R, Graffin P, Coq B . Catal. Lett., 2001,71:181. http://link.springer.com/10.1023/A:1009007321914

DOI: 10.1023/A:1009007321914

本文引用 [1]
[147]
Unnikrishnan R, Narayanan S . J. Mol. Catal. A, 1999,144:173. https://linkinghub.elsevier.com/retrieve/pii/S1381116998003550

DOI: 10.1016/S1381-1169(98)00355-0

本文引用 [1]
[148]
Tronto J, Crepaldi E L, Pavan P C, Cipriano De Paula C, Valim J B . Mol. Cryst. Liq. Cryst., 2001,356:227. https://www.tandfonline.com/doi/full/10.1080/10587250108023703

DOI: 10.1080/10587250108023703

本文引用 [1]
[149]
Choy J H, Oh J M, Park M, Sohn K M, Kim J W . Adv. Mater., 2004,16:1181. http://doi.wiley.com/10.1002/%28ISSN%291521-4095

DOI: 10.1002/(ISSN)1521-4095

本文引用 [1]
[150]
Aisawa S, Takahashi S, Ogasawara W, Umetsu Y, Narita E . J. Solid State Chem., 2001,162:52. https://linkinghub.elsevier.com/retrieve/pii/S0022459601993405

DOI: 10.1006/jssc.2001.9340

本文引用 [1]
[151]
Zebda A, Tingry S, Innocent C, Cosnier S, Forano C, Mousty C . Electrochim. Acta, 2011,56:10378. https://linkinghub.elsevier.com/retrieve/pii/S0013468611001757

DOI: 10.1016/j.electacta.2011.01.101

本文引用 [2]
[152]
Drezdzon M A . Inorg. Chem., 1988,27:4628. https://www.ncbi.nlm.nih.gov/pubmed/20491106

DOI: 10.1002/anie.201001003   PMID: 20491106

本文引用 [1]
[153]
Tronto J, dos Reis M J, Silvério F, Balbo V R, Marchetti J M, Valim J B . J. Phys. Chem. Solids, 2004,65:475. https://linkinghub.elsevier.com/retrieve/pii/S0022369703004335

DOI: 10.1016/j.jpcs.2003.09.019

本文引用 [1]
[154]
Al-Gohary O M, Hosny E A . Pharmaceut. Acta, 1997,72:81.
本文引用 [1]
[155]
Al-Gohary O M, Al-Kassas R S . Pharmaceut. Acta, 2000,74:351.
本文引用 [1]
[156]
Wei M, Yuan Q, Evans D G, Wang Z, Duan X . J. Mater. Chem., 2005,15:1197. http://xlink.rsc.org/?DOI=B416068A

DOI: 10.1039/B416068A

本文引用 [1]
[157]
Li F, Jin L, Han J, Wei M, Li C . Indus. Eng. Chem. Res., 2009,48:5590. https://pubs.acs.org/doi/10.1021/ie900043r

DOI: 10.1021/ie900043r

本文引用 [1]
[158]
Shan D, Cosnier S, Mousty C . Analyt. Chem., 2003,75:3872. https://pubs.acs.org/doi/10.1021/ac030030v

DOI: 10.1021/ac030030v

本文引用 [1]
[159]
De Melo J, Cosnier S, Mousty C, Martelet C, Jaffrezic-Renault N . Analyt. Chem., 2002,74:4037. https://www.ncbi.nlm.nih.gov/pubmed/12199571

DOI: 10.1021/ac025627+   PMID: 12199571

本文引用 [1] 摘要

Enzyme-based field effect transistors (ENFETs) for urea determination were developed based on the immobilization of urease within two different clay matrixes, one cationic (Laponite) and the other anionic (layered double hydroxide (LDH)), cross-linked with glutaraldehyde. The biosensor based on the enzyme immobilized in Laponite shows a greater sensitivity and smaller dynamic linear range, because the enzymatic reaction is protected from the effect of the buffer capacity of the outer medium. The apparent Michaelis-Menten constant, Km(app), is quite similar for both biosensors. Inhibition of the enzyme by sodium tetraborate was investigated. Tetraborate acts as a competitive inhibitor for urease in the two different types of clay, the inhibitor effect being stronger for the LDH/urease biosensor. In particular, the maximum limit of the dynamic linear range extends from 1.4 mM in the absence of the inhibitor to 12 mM in the presence of 0.5 mM tetraborate. The Km(app) values in the presence of 0.5 mM tetraborate for Laponite and LDH biomembranes were 10 and 62 mM, respectively. Comparison of the inhibition constant values, Ki 0.16 and 0.05 mM for Laponite and LDH biosensors, respectively, clearly indicates a stronger enzyme-inhibitor interaction in the LDH/urease biomembrane.
[160]
Ai H, Huang X, Zhu Z, Liu J, Chi Q, Li Y, Li Z, Ji X . Biosens. Bioelectron., 2008,24:1048. https://linkinghub.elsevier.com/retrieve/pii/S0956566308004089

DOI: 10.1016/j.bios.2008.07.039

本文引用 [1]
[161]
Forano C, Vial S, Mousty C . Curr. Nanosci., 2006,2:283. <![CDATA[http://www.eurekaselect.com/openurl/content.php?genre=article&issn=1573-4137&volume=2&issue=3&spage=283]]>

DOI: 10.2174/1573413710602030283

本文引用 [1]
[162]
Desigaux L, Belkacem M B, Richard P, Cellier J, Léone P, Cario L, Leroux F, Taviot-Guého C, Pitard B . Nano Lett., 2006,6:199. https://www.ncbi.nlm.nih.gov/pubmed/16464034

DOI: 10.1021/nl052020a   PMID: 16464034

本文引用 [1] 摘要

The purpose of this study was to control the fabrication of new labile supramolecular assemblies by formulating associations of DNA molecules with inorganic layered double hydroxides (LDHs). The results show that LDH/DNA hybrids synthesized by a coprecipitation route involving the in situ formation of LDHs around DNA molecules acting as templates were characterized by a lamellar organization, with DNA molecules sandwiched between hydroxide layers, exhibiting a regular spacing of 1.96 nm. Our results indicate that labile complexes resulting from the association of nucleic acids and inorganic materials can be obtained not only by anion exchange but also by a direct self-assembly route.
[163]
Oh J M, Kwak S Y, Choy J H . J. Phys. Chem. Solids, 2006,67:1028. https://linkinghub.elsevier.com/retrieve/pii/S0022369706000321

DOI: 10.1016/j.jpcs.2006.01.080

本文引用 [1]
[164]
Williams G R, O’Hare D . J. Mater. Chem., 2006,16:3065. http://xlink.rsc.org/?DOI=b604895a

DOI: 10.1039/b604895a

本文引用 [1]
[165]
Reddy M R, Xu Z, Lu G, Diniz da Costa J . Indus. Eng. Chem. Res., 2008,47:7357. https://pubs.acs.org/doi/10.1021/ie8004226

DOI: 10.1021/ie8004226

本文引用 [1]
[166]
Yoon S, Moon J, Bae S, Duan X, Giannelis E P, Monteiro P M . Mater. Chem. Phys., 2014,145:376. https://linkinghub.elsevier.com/retrieve/pii/S0254058414001163

DOI: 10.1016/j.matchemphys.2014.02.026

本文引用 [1]
[167]
Ge Y, Kan K, Yang Y, Zhou L, Jing L, Shen P, Li L, Shi K . J. Mater. Chem. A, 2014,2:4961. http://xlink.rsc.org/?DOI=c3ta14607c

DOI: 10.1039/c3ta14607c

本文引用 [1]
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