Layered Double Hydroxides Host Research Articles

Vitamin B3 Intercalated in Layered Double Hydroxides: A Drug Delivery System for Metabolic Regulation.

The organic compound niacin or nicotinic acid, also known as vitamin B3 (VitB3), is essential for human nutrition and metabolic regulation. However, in high doses, it can provoke side effects, such as hyperglycemia, liver damage, and flushing. Development of a controlled release system that slowly releases VitB3 into the organism would avoid high dosing peaks, thus contributing to decrease the occurrence of side effects in nutritional supplementation. Here, we show that the slow and controlled release of VitB3 in an acid environment can be achieved via its intercalation in layered double hydroxides (LDHs). The synthesis of a ZnAl-VitB3 system is shown, in which VitB3 is intercalated in a ZnAl LDH. The presence of VitB3 in the ZnAl-VitB3 system was confirmed by elemental analysis, infrared (FTIR) and NMR spectroscopy, while successful intercalation in the LDHs was revealed by powder X-ray diffraction (PXRD). In vitro release tests were carried out in a concentrated HCl solution of pH 1.5, a pH similar to the human stomach environment. The results showed a steady release of VitB3 from the LDH host, with 90% of the vitamin liberated in the first 60 min after the suspension of the LDH in the acidic solution.

Heteroatoms introduction via Temperature-Differential doping strategy achieves Long-Cycle-Life NiCoMo-P LDH cathode for rechargeable Chloride-Ion battery

As one of the most promising insertion-type cathodes for the novel chloride ion batteries (CIBs), layered double hydroxides (LDHs) materials have been extensively investigated in the recent years as the typical inorganic anion conductors. Nevertheless, poor intrinsic conductivity and sluggish reaction kinetics of LDHs challenge directly the further development in terms of chloride storage capacity and cycling life. Herein, phosphorus doped NiCoMo LDH in chloride form (NiCoMo-P LDH) is demonstrated as a high performance cathode for CIB. The unique temperature-differential doping methode allows P heteroatoms to incorporate into the metal–oxygen octahedral matrix of LDHs host layers, which have no effect on the entire crystal structure of 2D LDHs and the stable presence of interlayer Cl ions. By combining the advanced spectroscopy techniques and DFT theoretical calculations, abundant vacancies are proved to be introduced into NiCoMo-P LDH and both the conductivity and chloride-ion diffusion rate are significantly improved, providing more active adsorption sites for electrochemical reactions, thus strengthening the Cl ions storage performance with a stable discharge capacity of 150.2 after 800 charging/discharging processes at a current density of 300 mA g−1. This study presents a facile strategy for the rational doping of hetero-anions in LDHs materials for CIBs at relative low-temperature, which can also be adopted in other types of halide-ion-based rechargeable batteries.

Mechanism of Sodium Dodecyl Diphenyl Ether Disulfonate Filled Hydrotalcite Inhibiting the Photo-Degradation of Polyvinyl Chloride under Different Ranges of Ultraviolet Wavelength Irradiation

This content introduces a novel Ultraviolet (UV)-shielding material, Zn2Al-MADS-LDH (MADS-LDH), which was synthesized through co-precipitation method to insert sodium dodecyl diphenyl ether disulfonate (MADS) into the interlayer of Zn2Al-LDH layered double hydroxide (LDH), to improve the photoaging resistance of polyvinyl chloride (PVC). The characterization results indicated that MADS-LDH had a host-guest interaction between the LDH host layer and MADS guest anion, and it exhibited superior UV absorption capabilities than Zn2Al-CO3-LDH (CO3-LDH) and a broader absorption spectrum compared to MADS. A series of LDHs/PVC film composite materials containing LDHs nanosheets were prepared by incorporating the prepared LDHs into a PVC matrix via a solvent casting method. As expected, the MADS-LDH/PVC film composite materials exhibited enhanced photoaging resistance. The results of photoaging tests indicated that MADS-LDH inhibits the rate of carbonyl generation during photoaging of MADS-LDH/PVC film composite materials, resulting in a decrease in the carbonyl index (ΔCl) and relative degradation rate (RDR) compared to pristine PVC film and CO3-LDH/PVC film composite materials. Furthermore, the study evaluated the influence of different UV light wavelength ranges, such as UVB (280~315 nm), UVC (200~280 nm), and UV (200~400 nm), on the aging performance of PVC film and LDHs/PVC film composite materials. The results demonstrated that UV had the highest aging effect on PVC composite films, followed by UVC and UVB. Therefore, the MADS-LDH is a highly efficient and promising UV-shielding material with excellent potential for wide applications in the field of PVC.

Interleaved Electroactive Molecules into LDH Working on Both Electrodes of an Aqueous Battery-Type Device.

By selecting two electroactive species immobilized in a layered double hydroxide backbone (LDH) host, one able to act as a positive electrode material and the other as a negative one, it was possible to match their capacity to design an innovative energy storage device. Each electrode material is based on electroactive species, riboflavin phosphate (RF) on one side and ferrocene carboxylate (FCm) on the other, both interleaved into a layered double hydroxide (LDH) host structure to avoid any possible molecule migration and instability. The intercalation of the electroactive guest molecules is demonstrated by X-ray diffraction with the observation of an interlayer LDH spacing of about 2 nm in each case. When successfully hosted into LDH interlayer space, the electrochemical behavior of each hybrid assembly was scrutinized separately in aqueous electrolyte to characterize the redox reaction occurring upon cycling and found to be a rapid faradic type. Both electrode materials were placed face to face to achieve a new aqueous battery (16C rate) that provides a first cycle-capacity of about 7 mAh per gram of working electrode material LDH/FCm at 10 mV/s over a voltage window of 2.2 V in 1M sodium acetate, thus validating the hybrid LDH host approach on both electrode materials even if the cyclability of the assembly has not yet been met.

Introducing high-valence molybdenum to stimulate lattice oxygen in a NiCo LDH cathode for chloride ion batteries.

Layered double hydroxides (LDHs) have been intensively investigated as promising cathodes for the new concept chloride ion battery (CIB) with multiple advantages of high theoretical energy density, abundant raw materials and unique dendrite-free characteristics. However, driven by the great compositional diversity, a complete understanding of interactions between metal cations, as well as a synergetic effect between metal cations and lattice oxygen on LDH host layers in terms of the reversible Cl-storage capability, is still a crucial but elusive issue. In this work, we synthesized a series of chloride-inserted trinary Mox-doped NiCo2-Cl LDH (x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5) with gradient oxygen vacancies as enhanced cathodes toward CIBs. The combination of advanced spectroscopic techniques and theoretical calculations reveals that the Mo dopant facilitates oxygen vacancy formation and varies the valence states of coordinated transition metals, which can not only tune the electronic structure effectively and promote Cl-ion diffusion, but improve the redox activity of LDHs. The optimized Mo0.3NiCo2-Cl LDH delivers a reversible discharge capacity of 159.7 mA h g-1 after 300 cycles at 150 mA g-1, which is almost a triple enhancement compared to that of NiCo2Cl LDH. The superior Cl-storage of trinary Mo0.3NiCo2Cl LDH is attributed to the reversible intercalation/deintercalation of chloride ions in the LDH gallery along with the oxidation state changes in Ni0/Ni2+/Ni3+, Co0/Co2+/Co3+ and Mo4+/Mo6+ couples. This simple vacancy engineering strategy provides critical insights into the significance of the chemical interaction of various components on LDH laminates and aims to effectively design more LDH-based cathodes for CIBs, which can even be extended to other halide-ion batteries like fluoride ion batteries and bromide ion batteries.

Dual-purpose nickel-iron layered double hydroxides by controlled lanthanide and phosphide incorporation for promoting overall water splitting efficiency

Developing non-noble metal and binder-free bifunctional electrocatalysts is of paramount importance but challenging for simultaneously promoting oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) processes. In the work, we introduce the dual-purpose utilization of nickel-iron layered double hydroxides (LDH) by a lanthanide and phosphide incorporation strategy for highly efficient overall water splitting (OWS). The screening of lanthanides effect shows that the lanthanide dopants (Ce, La and Nd) greatly contribute to the layer lattice distortion of LDH host structure and strong electronic interaction with Fe2+ species, leading to the increment of OER active species content of α-Ni(OH)2 phase and Fe3+. Specially, the formation of Ce3+/4+ reversible redox species can significantly promote charge transfer efficiency, thus corporately attributing to the excellent OER activity (η10 = 207 mV) and durability (300 mA·cm−2 for 200 h). On the other hand, we found that with further phosphide anions engineering, the HER Volmer step is accelerated in lanthanide and phosphide co-doped LDH, as compared to the solely phosphide doped LDH. The present of co-doped lanthanide can modify the adsorption energy of hydrogen intermediates and the Ce3+/4+ reversible redox species also facilitate the formation of HER active Ni2P phase, resulting in the lowest η10 value of 134 mV. The dual-purpose configuration of the Ce LDH // Ce LDH-P electrodes, provides low OWS potentials of 1.638 and 1.839 V to reach current densities of 10 and 100 mA·cm−2, respectively. These findings could introduce a new way to integrate nonprecious-metal bifunctional electrocatalysts into an efficient OWS system.

Enhanced thermal and photo-stability of a para-substituted dicumyl ketone intercalated in a layered double hydroxide.

A ketodiacid, 4,4′-dicarboxylate-dicumyl ketone (3), has been intercalated into a Zn, Al layered double hydroxide (LDH) by a coprecipitation synthesis strategy. The structure and chemical composition of the resultant hybrid material (LDH-KDA3) were characterized by powder X-ray diffraction (PXRD), FT-IR, FT-Raman and solid-state 13C{1H} NMR spectroscopies, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), and elemental analysis (CHN). PXRD showed that the dicarboxylate guest molecules assembled into a monolayer to give a basal spacing of 18.0 Å. TGA revealed that the organic guest starts to decompose at a significantly higher temperature (ca. 330°C) than that determined for the free ketodiacid (ca. 230°C). Photochemical experiments were performed to probe the photoreactivity of the ketoacid in the crystalline state, in solution, and as a guest embedded within the photochemically-inert LDH host. Irradiation of the bulk crystalline ketoacid results in photodecarbonylation and the exclusive formation of the radical-radical combination product. Solution studies employing the standard myoglobin (Mb) assay for quantification of released CO showed that the ketoacid behaved as a photoactivatable CO-releasing molecule for transfer of CO to heme proteins, although the photoreactivity was low. No photoinduced release of CO was found for the LDH system, indicating that molecular confinement enhanced the photo-stability of the hexasubstituted ketone. To better understand the behavior of 3 under irradiation, a more comprehensive study, involving excitation of this compound in DMSO-d6 followed by 1H NMR, UV-Vis and fluorescence spectroscopy, was undertaken and further rationalized with the help of time-dependent density functional theory (TDDFT) electronic quantum calculations. The photophysical study showed the formation of a less emissive compound (or compounds). New signals in the 1H NMR spectra were attributed to photoproducts obtained via Norrish type I α-cleavage decarbonylation and Norrish type II (followed by CH3 migration) pathways. TDDFT calculations predicted that the formation of a keto-enol system (via a CH3 migration step in the type II pathway) was highly favorable and consistent with the observed spectral data.

Facile and fast preparation of layered double hydroxide as a nanocarrier for ascorbic acid under ultrasonic irradiation.

Background and purpose:Layered double hydroxides (LDHs) as inorganic materials are being used in controlled release and drug delivery systems. These materials are more stable than conventional drug carriers. In this investigation, Mg/Al-ascorbic acid (ASA) LDH nanohybrid was synthesized by ultrasonic-assisted co-deposition techniques.Experimental approach:In this study, Mg/Al-LDH to adsorption of ASA anions from the alkaline solution was assembled by a facile coprecipitation technique. During this process, ultrasonic irradiation was used to increase the rate of ion exchange between LDH and ASA. The intercalated-layered structure was characterized by FT-IR spectroscopy, XRD, thermogravimetric analysis, field emission SEM, and TEM. ASA releasing from Mg/Al-ASA LDH nanohybrid was carried out in incubation sodium carbonate solution (0.5 M) at 35 °C using UV-Vis absorbance analysis at λ = 265 nmFindings/Results:The used techniques confirmed the structure of Mg/Al-LDH and indicated successful intercalation of ASA into the interlayer galleries of the LDH host. The obtained results also have shown that Mg/Al-ASA LDH nanohybrid was generated with an average diameter size of 25 nm and narrow size distribution. Analysis of the release profiles using several kinetic models suggested that the first-order rate model is the most appropriate for describing the release of ASA from Mg/Al-LDH which means the amount of drug released is proportional to the amount of remaining drug in the matrix. Thus, the amount of activity released tends to decrease in function of time.Conclusion and implications:The results showed that LDHs are good host materials to preserve the biomolecule and modify its release rate and bioavailability.

Europium-doped Zn-Al-LDH intercalated with 4-biphenylcarboxylate anion and undoped Zn-Al-LDH intercalated with its anionic Eu(III) complex: Structural and UV or X-ray excited luminescence properties

Undoped and doped layered double hydroxides (LDH) were obtained by coprecipitation and the bca (biphenyl-4-carboxylate) anion or [Eu(bca)4]- intercalation by solvothermal post treatment. The three systems, (i) [Zn2Al1-xEux]NO3-LDH x = 0.1 at.%, (ii) [Zn2Al1-xEux]bca-LDH x = 0.1 at.% and (iii) [Zn2Al][Eu(bca)4]-LDH are compared by XRD, FTIR, Zeta Potential, PLS and XEOL characterizations. The luminescent properties are exciting. The bca intercalation/coordination increases the luminescence intensity of the doped LDH because decreases the –OH groups, luminescence suppressors by multi-phonon process, and increases the ligand to Eu3+ energy transfer processes. The luminescence in the (iii) system is less intense than the (ii) system but more intense than (i) system and the Eu3+ symmetry in the intercalated complex is different from the free one. X-ray excited optical luminescence occurs on all systems with different radiation damage. The intense luminescence remarks the Eu3+ as an excellent spectroscopic probe, as dopant in the brucite-like layers and in the interlayer space as anion complex. Finally, the LDH host structure acts as a protective environment for the luminescence properties of intercalated species. Thus, LDH systems become potential candidates combining the inorganic and organic properties for promising emission materials.

Effect of MnO2/Mg–Al layered double hydroxide preparation method on the removal of NO

In this study, we prepared Mg–Al layered double hydroxide (LDH) by anion exchange and co-precipitation methods and investigated the influence of the preparation methods on the removal of NO. MnO2/Mg–Al LDH prepared using the rehydration and anion exchange methods exhibited very high NO removal rates, removing approximately 90 % of NO even after 90 min. In contrast, MnO2/Mg–Al LDH prepared using the co-precipitation method demonstrated a poor NO removing ability. Although Mn3+ species were distributed within the LDH host layers when MnO2/Mg–Al LDH was prepared by co-precipitation, they did not affect the oxidation of NO. Conversely, MnO2 and Mn2O3 remaining in the form of bridges after the intercalation and subsequent reduction of MnO4- species contributed to NO oxidation, which was observed for MnO2/Mg–Al LDH prepared using both anion exchange and co-precipitation methods. Thus, bridging between the LDH layers by MnO2 and Mn2O3 is essential for removing NO.

A defect-rich layered double hydroxide nanofiber filter with solar-driven regeneration for wastewater treatment

The need for environmental technology treatment of contaminants of emerging concerns (CECs) is increasing as CECs lead to detrimental effects on human health and ecosystems. Herein, defect-rich layered double hydroxide (LDH) structured into a fibrous filter with a facile solar-driven regeneration function was fabricated for efficiently removing adsorbed CECs in wastewater. The physical and chemical interactions between the LDH filter and CECs are revealed. It is demonstrated that the introduction of unsaturated Cuδ+ sites (δ < 2) and creating oxygen vacancies represents an effective way for improving adsorbing activity of the defect-rich LDH host layer. Also, the nanofiber-particle friction coefficient of the hierarchical LDH filter affects the filtration efficiency as revealed by 3D modelling. The LDH filter is capable of filtrating sixteen types of CECs and shows the capability of photocatalytic degradation of adsorbed CECs, thus enabling filter regeneration. This work thus presents a new perspective into bottom-up design of adsorbent materials: from molecular interactions to shaping adsorbents into microscopic nanofibers and assembling these into macroscopic 3D adsorbent filters.

Cobalt nanoparticle supported on layered double hydroxide: Effect of nanoparticle size on catalytic hydrogen production by NaBH4 hydrolysis

Catalytic hydrolysis of sodium borohydride (NaBH4) is a promising method to provide clean hydrogen (H2) energy for portable devices. Therefore, designing a non-noble metal catalyst that performs well in this hydrolysis is essential. Cobalt-nanoparticles (Co-NPs) supported on magnesium-aluminium layered double hydroxide (LDH) with various mean diameter were synthesized by changing concentration of cobalt-citrate anion (Co-citrate) precursor used for ion exchange with the LDH host. Then the Co-citrate intercalated LDHs were reduced with NaBH4 to form Co-NPs. Evidence of successful intercalation was shown by X-ray diffraction (XRD) and Fourier-Transform Infrared spectroscopy (FT-IR). Transmission Electron Microscope (TEM) and Scanning TEM (STEM) observations revealed that Co-NPs were in metallic state and their mean diameter increased with the concentration of Co-citrate solution. Nitrogen physisorption isotherms showed that the surface structure of LDHs transformed from non-porous to mesoporous after chemical reduction, which indicated that the Co-NPs were formed in the interlayer of LDHs. Catalytic hydrolysis of NaBH4 at 25 °C clarified that the catalyst synthesized from 6 mM Co-citrate solution showed the highest H2 generation rate of 4520 ± 251 mL min−1·gCo−1, indicating the catalyst had the optimum size of Co-NP. This activity could be considered relatively higher compared to unsupported cobalt and many other supported cobalt-base catalysts previously reported. It was also clearly shown that size of Co-NPs supported on LDH could be a significant parameter as it allowed better accessibility of reactants to the active catalyst surface to obtain maximum activity. For this optimum catalyst, the activation energy was evaluated to be 56.9 kJ mol−1. Although the catalyst was able to achieve almost the same conversion when the catalyst was repeatedly tested five times under the same condition, the catalytic activity decreased gradually. Overall, it could be revealed that Co-NPs supported on LDHs have a huge potential to be used for H2 energy production.

Synthesis of layered double hydroxide nanosheets in an aqueous solvent and their Ni2+ uptake characteristics

Two-dimensional (2D) nanomaterials have drawn widespread attention because of their unique physical characteristics compared to three-dimensional materials. Delamination and nanosheet formation of layered composites are necessary for 2D nanomaterials. Layered double hydroxides (LDH) exhibit anion exchange properties that can be maximized using different methods such as organic modifications and crystal growth control; delamination is one such method. Delamination of LDH render them in the form of nanosheets, which could not be expressed as interlayers, allowing them to exhibit physical properties completely different from those of bulk LDH. Herein, we propose a novel synthesis method to delaminate LDH in an aqueous solvent. In this method, heat reflux is used to break interlayer hydrogen bonds in the LDH, and the remaining hydrogen bonds are broken using ultrasonic treatment. Finally, we dispersed the material in the solvent to obtain LDH nanosheets. We compared the delamination of MgAl LDH intercalated with lactate (lactate•Mg–Al LDH) and MgAl LDH intercalated with NO3− (NO3·Mg–Al LDH) in an aqueous solvent. Furthermore, we used the nanosheets obtained from NO3·Mg–Al LDH and described their Ni2+ uptake characteristics. Our results show that without using organic solvents, we could delaminate lactate•Mg–Al LDH and NO3·Mg–Al LDH by applying the proposed method. The lactate•Mg–Al LDH had approximately ten MgAl LDH host layers, whereas the corresponding nanosheets had three MgAl LDH host layers. NO3·Mg–Al LDH had 14–15 Mg–Al LDH host layers, whereas the corresponding nanosheets had 2–3 Mg–Al LDH host layers. Furthermore, NO3·Mg–Al LDH and its nanosheets could adsorb Ni2+ in an aqueous solvent. Thus, Ni2+ uptake capabilities were enhanced by delaminating NO3·Mg–Al LDH to fabricate nanosheets.

One‐Pot Intercalation Strategy for the Encapsulation of a CO‐Releasing Organometallic Molecule in a Layered Double Hydroxide

The photoactivatable CO‐releasing molecule (photoCORM) [Mo(CO)3(CNCH2COOH)3] (ALF795) has been incorporated into a Zn,Al layered double hydroxide (LDH) host by a coprecipitation synthesis strategy. Powder X‐ray diffraction (PXRD) of the resultant material Zn,Al‐ALF795 showed that the ALF795 guest molecules assembled into a monolayer to give a basal spacing of 16.0 Å. FTIR and 13C{1H} CP MAS NMR spectroscopy confirmed that the molecular structure of the tricarbonyl complex was retained upon intercalation. Scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDS) and elemental analyses confirmed the phase‐purity of Zn,Al‐ALF795. The myoglobin assay was used to demonstrate that intercalated ALF795 retains the photoactive behavior of the free CORM, with a substantial fraction (42 %) of the high CO payload (2.46 mmol g–1) being released after exposure to UV light for 3 h under simulated physiological conditions. In addition, gas chromatography was used to track sequential light‐ and H2O2‐triggered decarbonylation of free and intercalated ALF795. In biological buffer solution (HEPES), less than 2 % Mo leaching from Zn,Al‐ALF795 took place after 5 h, showing the strong capacity of the LDH host to retain the unaltered complex and decarbonylation fragments.

Preparation of Zn–Al layered double hydroxide intercalated with carboxymethyl-β-cyclodextrin by anion exchange method and its Ni2+ adsorption property

ABSTRACT Recently, layered double hydroxides (LDHs) have been extensively researched for their anion exchange capabilities and exhibit a layered structure with a host layer of octahedrally coordinated metal cations and a guest layer (interlayer) of anions. In this study, we synthesized a CM-β-CD•Zn–Al LDH by anion exchange method to study the anionization of cyclodextrin (CD) to promote its incorporation into the LDH interlayers and its stability therein. Ni2+ adsorption by the CMCD•Zn–Al LDH by the anion exchange method was compared with the results co-precipitation method. The X-ray diffraction spectra of NO3•Zn–Al LDH and CM-β-CD•Zn–Al LDH synthesized by the anion exchange method exhibit that the product peaks were attributable to and possessed an LDH structure. Furthermore, all CM-β-CD•Zn–Al LDHs exhibited the presence of some CM-β-CD. The CM-β-CD•Zn–Al LDH was hypothesized to be composed of two types of layers: a CM-β-CD layer in which two molecules of CM-β-CD7 -, with cavity axes perpendicular to the LDH host layer, are vertically overlaid, and a NO3-type Zn–Al LDH layer used as a precursor. CM-β-CD•Zn–Al LDH adsorbed Ni2+ in an aqueous solution. To determine whether Ni2+ adsorption by the CM-β-CD•Zn–Al LDH is driven chemically or physically, we fitted the data to the Freundlich and Langmuir adsorption models; the results showed that Ni2+ adsorption by the CM-β-CD•Zn–Al LDH is consistent with the Langmuir equation and could be considered a chemical adsorption.

Luminescent N-heterocycles based molecular backbone interleaved within LDH host structure and dispersed into polymer

A pyrazino-1,3a,6a-triazapentalene dye-based molecule was intercalated by direct co-precipitation method into the galleries of negatively charged layered double hydroxide (LDH) to form a new luminescent LDH filler. The materials of cation composition Zn/Al = 2 lead to well-defined organic inorganic assemblies. The structure of the hybrid materials was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectra (FTIR) and UV–visible spectra. Optical properties of the materials, at both solid state and slurry state, were also recorded and absolute photoluminescent quantum yields (PLQY) were determined showing that the nanohybrid LDH slurry exhibited higher luminescence properties under UV excitation than the corresponding LDH powder. LDH fillers were used to prepare composite films by dispersion in both hydrophobic or hydrophilic polymer matrix such as poly (dimethyl siloxane) (PDMS) and poly(ethylene oxide) (PEO), respectively. Composite films were characterized by Small Angle X-ray Scattering (SAXS) and PLQY were recorded in order to compare the behaviour of the nanohybrid LDH filler in both polymer matrices. It was found that the aggregation of particles is still observed by SAXS.

Nanolayered composite with enhanced ultraviolet ray absorption properties from simultaneous intercalation of sunscreen molecules

IntroductionThe potential of layered double hydroxide (LDH) as a host of multiple ultraviolet-ray absorbers was investigated by simultaneous intercalation of benzophenone 4 (B4) and Eusolex® 232 (EUS) in Zn/Al LDH.MethodsThe nanocomposites were prepared via coprecipitation method at various molar ratios of B4 and EUS.ResultsAt equal molar ratios, the obtained nanocomposite showed an intercalation selectivity that is preferential to EUS. However, the selectivity ratio of intercalated anions was shown to be capable of being altered by adjusting the molar ratio of intended guests during synthesis. Dual-guest nanocomposite synthesized with B4:EUS molar ratio 3:1 (ZEB [3:1]) showed an intercalation selectivity ratio of B4:EUS =53:47. Properties of ZEB (3:1) were monitored using powder X-ray diffractometer to show a basal spacing of 21.8 Å. Direct-injection mass spectra, Fourier transform infrared spectra, and ultraviolet–visible spectra confirmed the dual intercalation of both anions into the interlayer regions of dual-guest nanocomposite. The cytotoxicity study of dual-guest nanocomposite ZEB (3:1) on human dermal fibroblast cells showed no significant toxicity until 25 μg/mL.ConclusionOverall, the findings demonstrate successful customization of ultraviolet-ray absorbers composition in LDH host.

Delamination and self-assembly of layered double hydroxides for enhanced loading capacity and corrosion protection performance

Layered double hydroxides (LDHs) nanocontainers intercalating with corrosion inhibitors are considered as a great platform to deliver corrosion inhibitors to the corroding sites. However, the small interlayer spacing and strong interaction between hydrotalcite laminates and interlayer anions impede the loading of macromolecular species into LDHs via a conventional anion-exchange process. This work devises a new paradigm for the preparation of LDHs in corrosion protection. A new method combining delamination and self-assembly to increase the loading of the organic corrosion inhibitor —5-Methyl-1,3,4-thiadiazole-2-thiol (MTT) into LDHs is applied and exhibits remarkable corrosion protection effects. The SEM, EDS, TEM, XRD, XPS and FT-IR were used to characterize the LDHs and LDH nanosheets. UV–vis absorption spectra and thermogravimetric analysis (TGA) experiments indicate an enhanced loading of MTT which is slowly released to the chloride media. The electrochemical experiments indicate that the release of MTT from their LDHs host can efficiently inhibit the corrosion on the surface of mild steel in 3.5 wt% NaCl solution. Furthermore, surface analysis experiments were carried out to probe into the anticorrosion mechanism of LDHs.

Nickel–Iron Layered Double Hydroxide Hollow Polyhedrons as a Superior Sulfur Host for Lithium–Sulfur Batteries

AbstractWe have designed and synthesized novel hollow Ni/Fe layered double hydroxide (LDH) polyhedrons as an advanced sulfur host for enhancing the performance of lithium–sulfur (Li–S) batteries. The Ni/Fe LDH host shows multiple advantages. First, the Ni/Fe LDH shells can provide sufficient sulfiphilic sites for chemically bonding with polysulfides. Second, the hollow architecture can provide sufficient inner space for both loading a large amount of sulfur and accommodating its large volumetric expansion. Moreover, once the active material is confined within the host, the shells could easily restrict the outward diffusion of polysulfides, guaranteeing prolonged cycle life even with high sulfur loading. As a result, the S@Ni/Fe LDH cathode has successfully solved the main issues related to sulfur electrodes, and it exhibits significantly improved electrochemical performances with prolonged life over 1000 cycles and excellent rate properties.

Nickel-Iron Layered Double Hydroxide Hollow Polyhedrons as a Superior Sulfur Host for Lithium-Sulfur Batteries.

We have designed and synthesized novel hollow Ni/Fe layered double hydroxide (LDH) polyhedrons as an advanced sulfur host for enhancing the performance of lithium-sulfur (Li-S) batteries. The Ni/Fe LDH host shows multiple advantages. First, the Ni/Fe LDH shells can provide sufficient sulfiphilic sites for chemically bonding with polysulfides. Second, the hollow architecture can provide sufficient inner space for both loading a large amount of sulfur and accommodating its large volumetric expansion. Moreover, once the active material is confined within the host, the shells could easily restrict the outward diffusion of polysulfides, guaranteeing prolonged cycle life even with high sulfur loading. As a result, the S@Ni/Fe LDH cathode has successfully solved the main issues related to sulfur electrodes, and it exhibits significantly improved electrochemical performances with prolonged life over 1000 cycles and excellent rate properties.