Layered Double Hydroxide Nanosheets Research Articles

Short-time potentiostatic assisted borate to induce the generation of ultrathin NiFe LDH active phase for industrial-level water oxidation

Self-supported NiFe-based oxygen evolution reaction (OER) catalysts with high activity and durability are essential for the industrialization of green hydrogen. Herein, Boron-interfered NiFe LDH nanosheets (B2-NiFe-(a-10)) with abundant wrinkle structure are prepared by introducing nonmetallic sources into the surface reconstruction of layered double hydroxide (NiFe LDH) through a novel short-time potential constant activation strategy. It enhances interactions with the electrolyte, decreases Arrhenius activation energy (Ea), accelerates efficient charge transfer and O2 escape rate. The as-reconstructed B2-NiFe-(a-10) exhibits outstanding alkaline OER activity with an ultralow overpotential of 290 mV at 100 mA cm−2 and excellent durability (100 h). Additionally, density functional theory calculations further reveal that the interaction optimizes the adsorption of oxygenated intermediates (*OH→*O), induces the center of the d-band toward the Fermi energy level, and lowers the dissociation barrier of H2O. Moreover, the anion-exchange membrane water electrolyzer (AEMWE) achieves a current density of 1 A cm−2 at 1.97 V.

Ultra-flexible inorganic coating realized by scale-like nanosheets

Rapid development of foldable devices poses a challenging requirement on functional inorganic coatings with high flexibility. However, the inherent brittleness often renders inorganic coatings incompatible with flexibility. How to make flexible inorganic coatings remains challenging. Here, inspired by the scale structure of animal skins, we realize ultra-flexible scale-like coatings on polyimide (PI) film with layered double hydroxide (LDH) nanosheets. The adhesion is enhanced without peeling due to the bonding of polyimide with amino group attached to nanosheets. LDH nanosheets parallel to the substrate form scale-like structure that absorbs and releases stress to prevent coatings from cracking. And the coatings exhibit ultra-flexibility by surviving from 20,000 cycles of bending fatigue test. We apply the LDH-coated PI for atomic oxygen protection, which has important applications in aerospace industry. The coatings are designed as this special scale-like structure to release stress while possessing protection ability. Due to the barrier and adsorption of this flexible LDH coating, the erosion yield of the PI under an exposure of ~5 × 1021 atoms/cm2 is decreased by about 4 orders of magnitude to 0.015 % (~5 × 10−28 cm3/atom), which can satisfy the requirement for applications in harsh space environment of low earth orbit. Our work provides a general solution for simultaneously realizing high mechanical strength and flexibility in the coating technology, which may find applications in other areas, such as flexible electronics.

Cu3P Nanoarrays Fabricated on Copper Foam Substrates Followed by Coating with CoFe Layered Double Hydroxide Nanosheets as Electrocatalysts for Water Splitting

Cu₃P Nanoarrays Fabricated on Copper Foam Substrates Followed by Coating with CoFe Layered Double Hydroxide Nanosheets as Electrocatalysts for Water Splitting

Bioactive Layered Double Hydroxides for Synergistic Sonodynamic/Cuproptosis Anticancer Therapy with Elicitation of the Immune Response.

Sonodynamic therapy (SDT) has promising application prospects in tumor therapy. However, SDT does not eradicate metastatic tumors. Herein, Cu-substituted ZnAl ternary layered double hydroxide nanosheets (ZCA NSs) were developed as both sonosensitizers and copper nanocarriers for synergistic SDT/cuproptosis cancer therapy. An optimized electronic structure more conducive to the sonodynamic process was obtained from ZCA NSs via the Jahn-Teller effect induced by the introduction of Cu2+, and the synthesized ZCA NSs regulated the intricate tumor microenvironment (TME) by depleting endogenous glutathione (GSH) to amplify oxidative stress for further enhanced SDT performance. Furthermore, cuproptosis was evoked by intracellular overload of Cu2+ and amplified by SDT, leading to irreversible proteotoxicity. In vitro results showed that such synergetic SDT/cuproptosis triggered immunogenic cell death (ICD) and promoted the maturation of dendritic cells (DCs). Furthermore, the as-synthesized ZCA NS-mediated SDT/cuproptosis thoroughly eradicated the in vivo solid tumors and simultaneously elicited antitumor immunity to suppress lung and liver metastasis. Overall, this work established a nanoplatform for synergistic SDT/cuproptosis with a satisfactory antitumor immunity.

Investigation of Ag nanoparticles decorated Ni-Al layered double hydroxide as a gas sensor

Chemiresistive gas sensors based on LDH structure were investigated for the detection of widely used volatile organic compounds (VOCs) including methanol, ethanol, and acetone at room temperature. In order to increase the surface active sites and subsequently improve the detection sensitivity of gas molecules, the use of Ag decoration method along with the creation of porosity on the surface of LDH structures were investigated. In this method, methanol solvent was used as a hole scavenger and UV radiation as a catalyst for binding Ag to the surface of LDH sheets. The microstructure and morphology of the composites were investigated by FESEM, HRTEM, EDS, EDS mapping, XRD, and MS analysis. The investigated parameters included relative humidity, calibration curve, repeatability, selectivity, and response/recovery times. According to the obtained results, the creations of surface corrosion by methanol and decorating the structure with Ag have both affected the sensitivity of the sensors. The pure Ni-Al LDH sensor has a response value of 6.8–250 ppm of ethanol. By increasing the specific surface area and creating LDH nanosheets, the response value can be increased up to 8.52. Also, the addition of Ag NP (Ni-Al LDH decorated with Ag NP) has increased the response up to 10.89. It was also observed that the response times in different modes have the least difference. At the end, the response mechanism was investigated based on the heterojunction theory.

Layered assembly of PEGylated graphene oxide and Mg–Al layered double hydroxide nanosheets with superior adsorption capacity and selective isolation of hemoglobin

This study developed a novel organic-inorganic hybrid composite, shortly as GO-PEG-LDHs, by self-assembly of exfoliated Mg–Al layer double hydroxide (LDHs) on the polyethylene glycol (PEG) grafted graphene oxide (GO) to achieve the selective adsorption of hemoglobin (Hb). The prepared GO-PEG-LDHs has a hierarchical structure with a homogeneous loading of exfoliated LDHs nano-sheets on its surface. The adsorption test reveals that GO-PEG-LDHs exhibits an adsorption efficiency of 95.03% for Hb and 3.45% for bovine serum albumin (BSA). The adsorption of Hb follows the Langmuir model, with an ultrahigh adsorption capacity of 55248.6 mg/g, which is higher than any previously reported materials. Meanwhile, the adsorbed Hb can be efficiently recovered through elution with a 50 mM Tris-HCl buffer, with an elution efficiency of 80.77%. Circular dichroism (CD) spectra indicate no conformational change for Hb during the process of adsorption/desorption. Furthermore, the composite demonstrates the ability to selectively isolate Hb in the presence of interfering protein BSA, indicating its potential for practical applications.

Zn–Al LDH nanosheets exfoliated in a LiOH/urea solution in situ: an effective strategy for fabricating cellulosic fibres with enhanced mechanical properties

Zn–Al LDH nanosheets exfoliated in a LiOH/urea solution in situ: an effective strategy for fabricating cellulosic fibres with enhanced mechanical properties

Intracellular Delivery of Therapeutic Protein via Ultrathin Layered Double Hydroxide Nanosheets.

The therapeutic application of biofunctional proteins relies on their intracellular delivery, which is hindered by poor cellular uptake and transport from endosomes to cytoplasm. Herein, we constructed a two-dimensional (2D) ultrathin layered double hydroxide (LDH) nanosheet for the intracellular delivery of a cell-impermeable protein, gelonin, towards efficient and specific cancer treatment. The LDH nanosheet was synthesized via a facile method without using exfoliation agents and showed a high loading capacity of proteins (up to 182%). Using 2D and 3D 4T1 breast cancer cell models, LDH-gelonin demonstrated significantly higher cellular uptake efficiency, favorable endosome escape ability, and deep tumor penetration performance, leading to a higher anticancer efficiency, in comparison to free gelonin. This work provides a promising strategy and a generalized nanoplatform to efficiently deliver biofunctional proteins to unlock their therapeutic potential for cancer treatment.

High-Performance Catalytic Reduction of 4-Nitrophenol to 4-Aminophenol over Pt Nanoparticles Supported on Co-Al LDH Nanosheets

In this study, a Pt@Co-Al LDH hybrid structure was fabricated by assembling the metal precursor PtCl62− with the exfoliated LDH nanosheets followed by in situ reduction by NaBH4. The morphology, composition and microstructure of the hybrid were characterized by FESEM, HRTEM, XRD, XPS and BET techniques. Pt nanoparticles (NPs) with an average particle size of 3.1 nm were successfully and uniformly loaded on the surface of LDH nanosheets. The catalytic activity of the Pt@Co-Al LDH hybrid was tested for the reduction of 4-nitrophenol, which is one of the most frequent pollutants in wastewater effluent from the pharmaceutical and textile industries. The hybrid displays superior catalytic activity and stability in the reduction of 4-NP under environmental conditions with NaBH4 as a reducing agent. The hybrid can be recovered in a simple way and still shows high catalytic activity after five reuses.

Mixed matrix membranes based on morpholinium-functionalized CardoPES and MgAl-LDH: Structures, properties and electrodialysis performance

A simple, inexpensive, and effective method based on the MMMs prepared from morpholinium-functionalized CardoPES and MgAl-LDHs is proposed to improve the ED capabilities of AEMs. The microphase separation and ED performance of mixed matrix AEMs were substantially enhanced by LDH introduction, which was attributed to the surface OH groups of the LDH nanosheets; these interactions induced polymer chain self-assembly. The AEM with 8 % LDH exhibited the highest salt flux (92.5 mg/m2·s) during ED, which was 19.6 % and 14.1 % greater than those of the commercial Type 10 membrane and the mixed matrix AEM, respectively. Hydrogen bonding interactions and the ED capabilities of the AEMs were readily regulated by adjusting the feed ratios of the LDH and morpholinium groups. With increasing LDH content, the Rm and ED performance increased, while the hydrophilicity and mechanical properties initially decreased. When the OH content of an LDH nanosheet was higher than the morpholinium content, as the LDH content increased, the Rm and ED performance decreased, while the hydrophilicity and mechanical properties increased, which may be attributed to internal structural discrepancies between the complete and incomplete core-shell structures of the AEMs caused by different hydrogen bonding patterns.

Synergy of Mo doping and heterostructures in FeCo2S4@Mo-NiCo LDH/NF as durable and corrosion-resistance bifunctional electrocatalyst towards seawater electrolysis at industrial current density

Electrolysis of seawater to produce hydrogen is a replenished way to utilize sustainable hydrogen energy. However, it remains a challenge to develop electrocatalysts with high chloride corrosion resistance and meet the industrial-required low overpotential at large current density. Here, a heterostructure FeCo2S4@Mo-NiCo LDH/NF (FCS@M-NC LDH/NF) catalyst consisting of Mo-doped NiCo LDH nanosheets on FeCo2S4 nanorods grown on nickel foam is demonstrated as a large-current–density electrocatalyst for seawater electrolysis. The hierarchical structure endows FCS@M-NC LDH/NF with abundant active sites and hydrophilic and aerophobic surfaces, which promotes the adsorption of OH− and accelerates gas-release capabilities during water electrolysis. Moreover, the incorporation of high-valence Mo species and the presence of heterostructures contribute to the outstanding corrosion resistance, selectivity, and activity of FCS@M-NC LDH/NF, which only requires 314 mV (HER) and 307 mV (OER) overpotential to achieve a large current density of 1000 mA cm−2 in alkaline electrolysis of seawater. Impressively, it maintains stable operation for 140 h at a current density of 500 mA cm−2 without the production of hypochlorite. Furthermore, density functional theory calculations demonstrate that Mo doping and formation of heterostructures decrease the adsorption energy barrier for intermediate on FCS@M-NC LDH/NF, which promotes electrocatalytic activity. The robust electronic interaction between FCS and M-NC LDH/NF promotes the redistribution of charges on the interface, boosting electrical conductivity and charge transfer in the FCS@M-NC LDH/NF. This study offers a mild way to create a bifunctional electrocatalyst with exceptional corrosion resistance and stability in industrial high-alkaline natural seawater electrolysis.

Dual efficiency enhancement in overall water splitting with defect-rich and Ru atom-doped NiFe LDH nanosheets on NiCo2O4 nanowires

The development of layered double hydroxides (LDHs) as bifunctional catalysts for efficient overall water splitting by controlling the composition and structure of the material remains challenging. In this study, defect-rich and Ru-doped NiFe LDH nanosheet shells on NiCo2O4 (NCO) nanowires were successfully synthesized using a hydrothermal method, followed by alkaline etching. The resulting def-Ru-NiFe LDH/NCO (def = defects) catalyst exhibited remarkable catalytic activity with overpotentials of 122 and 225 mV for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively, at a current density of 10 mA cm−2. Density functional theory calculations demonstrated that atomic vacancy defects and the rational incorporation of Ru single atoms in def-Ru-NiFe LDH/NCO induced the regulation of the electronic structure and optimized the adsorption energies, thus enhancing the OER and HER performances. Particularly, an electrolyzer utilizing def-Ru-NiFe LDH/NCO exhibited exceptional performance, achieving cell voltages of 1.58 and 1.46 V in 1 M KOH at 25 and 75 °C, respectively. Moreover, the catalyst exhibited outstanding stability during 60 h of operation at a high applied voltage and temperature (75 °C). These results highlight the potential of def-Ru-NiFe LDH/NCO for hydrogen production.

Metal Organic Frameworks Derived Layered Double Hydroxide Nanosheets for Electrochemical Energy Storage and Conversion

AbstractPorous materials are promising for energy applications and MOF‐derived layered double hydroxide (LDH) nanosheets vertically align on the conductive substrates showed an ultrathin porous morphology with tunable coordination environments for the metallic sites. This unique structure provides larger surface area, better intrinsic electrochemical activity than conventional LDH nanosheets. Herein, the synthetic strategies of MOF‐derived LDHs and their promising applications in electrochemistry are reviewed, presenting the significant potential and challenges of MOFs‐derived LDH nanosheets in advanced energy storage and conversion applications, providing an effective platform for efficient and sustainable MOFs‐based systems in future.

Preparation of small-sized glucose-LDH nanosheets with good dispersibility using the coprecipitation and hydrothermal method with glucose as a polymerization inhibitor

In this study, small-sized glucose-LDH nanosheets were prepared using glucose as a polymerization inhibitor. The results indicated that glucose-LDH was successfully synthesized, and glucose molecules not only controlled the growth of LDH crystals and nanosheets but also inhibited the aggregation of the LDH nanosheets. Compared to that of LDH, the lateral size of glucose-LDH nanosheets prepared with 0.6 g of glucose addition decreased significantly, from 400 nm to about 50–100 nm. This novel strategy could be used for the preparation of other LDHs by changing the inorganic precursors.

CoO supported NiFe layered double hydroxide sandwich-like nanosheets on hierarchical carbon framework for efficient electrocatalytic oxygen evolution.

Exploration of greatly efficient and steady non-noble oxygen evolution reaction (OER) electrocatalysts is of great significance in improving the overall efficiency of energy density systems such as regenerative fuel cells, water electrolyzes, and metal-air batteries. Herein, inspired by hierarchical 3D porous structures with open microchannels of natural wood, CoO@NiFe LDH sandwich-like nanosheets were anchored on the carbonized wood (CW) via electrodeposition and calcination strategies. The strong interactions between CoO nanosheets and NiFe LDH nanosheets endow CoO@NiFe LDH/CW electrocatalyst with high catalytic properties toward the OER comparable to CoO/CW and NiFe LDH/CW. The optimized CoO@NiFe LDH/CW electrocatalyst demonstrates good OER catalytic performance with an overpotential of 230 mV at 100 mA cm-2. This work presents an innovative approach to utilize renewable resources for constructing advanced free-standing catalysts.

Surface-Modified LDH Nanosheets with High Dispersibility in Oil for Friction and Wear Reduction.

Surface and interfacial engineering of nanomaterials is essential for improving dispersion stability in liquids. In this study, we report that oleic acid (OA)- and stearic acid (SA)-functionalized layered double hydroxide (LDH) nanosheets as lubricant additives can achieve high dispersion and reduce friction and wear. LDH is a typical layered structure, and OA and SA are long-chain organic molecules that are not only compatible with base oils but also act as friction-reducing agents. The OA and SA molecules were branched onto ZnMgAl LDH nanosheets using dehydration condensation between the exposed OH groups on the surface of LDH and the COOH groups on the OA and SA molecules. Compared with that of the pristine ZnMgAl LDH, the dispersion of OA-ZnMgAl LDH and SA-ZnMgAl LDH was significantly improved. The surface-modified LDH exhibited superior tribological properties and great stability due to the synergistic lubrication effect between OA, SA, and LDH. Even at an ultralow concentration (0.15 wt %), the coefficient of friction and wear volume were reduced by ∼65 and ∼99%, respectively, compared to those of the base oil. Due to the green and simple synthesis method and excellent tribological properties, surface-functionalized LDH has enormous possibilities for future industrial applications.

Advanced hybrid supercapacitors assembled with CoNi LDH nanoflowers and nanosheets as high-performance cathode materials

In this work, CoNi layered double hydroxide with flower-like nanostructures (CoNi LDH NFs) and nanosheet-based shape (CoNi LDH NSs) were respectively prepared through a facile solvothermal approach, during which a mixed solvent of deionized water and ethylene glycol with different volume ratio was used. The NFs possessed a specific surface area of 101.28 m2 g−1 and was larger than the 38.54 m2 g−1 for NSs. The electrochemical performance of these CoNi LDHs was investigated in three-electrode & two-electrode systems, respectively, and they exhibited the battery-type electrochemical response. The CoNi LDH NFs delivered a specific capacity of 768.3C g−1 at 1 A g−1 and 643.1C g−1 at 10 A g−1, in contrast, the CoNi LDH NSs exhibited an inferior capacity of 669.3C g−1. To evaluate the practical application potential in the field of supercapacitor, the hybrid supercapacitor (HSC) device was assembled with these CoNi LDHs as cathode and activated carbon (AC) as anode. The CoNi LDH NFs//AC HSC delivered an energy density (ED) of 37.1 W h kg−1 at the power density (PD) of 748.0 W kg−1, which was higher than the 31.0 W h kg−1 for NSs-based HSC. The cycling performance and structural stability of such LDHs were investigated over 4000 cycles at a high current density of 10 A g−1, and just a little capacity decay at the end of cycling was found. The CoNi LDH NFs & NSs may serve as battery-grade electrode materials with high performance and probably have great application potential in electrochemical energy storage. Besides, the present synthetic method is simple and can be extended to the preparation of other LDHs for the assembly of advanced HSC device with superior electrochemical performance.

In-situ fabrication of Cr doped FeNi LDH on commercial stainless steel for oxygen evolution reaction

Commercial stainless steel has attracted increasing interest due to their rich content in transition metal elements and corrosion resistance properties. In this work, we design a facile and rapid route to in-situ fabricate the Cr doped FeNi layered double hydroxides nanosheets (LDHs) on modified stainless steel (Cr–FeNi LDH @ ESS) under ambient condition.The ultra small scaled 2D structure only around 20 nm diameter and metal ions with multivalent oxidation state were observed on the in situ fabricated LDHs, which provides high active area and active sites and thus promote excellent oxygen evolution reaction (OER). The Cr–FeNi LDH @ESS electrocatalysts exhibit an over potential of 280 mV at 10 mA cm−2 and achieves a Tafel slope of 44 mV dec−1 for OER in the 1.0 M KOH aqueous solution. We anticipate that the operating strategy of our system may promote the development of commercial non-precious productions as the efficient electrocatalysts for energy storage and conversion.

Controllable synthesis of layered double hydroxide nanosheets to build organic inhibitor-loaded nanocontainers for enhanced corrosion protection of carbon steel.

The development of layered double hydroxide (LDH) nanosheets as nanocontainers has been intensively studied in recent years. Despite their potential for application on a large scale, their synthesis in an aqueous medium is rarely reported. Herein, we report a straightforward approach for the controllable synthesis of uniform MgAl-LDH nanosheets by an aqueous nucleation process followed by a hydrothermal treatment. The key to this method relies on the well-dispersed LDH nuclei that are produced by high-speed homogenization. Following the nucleation step, the coalescence of the aggregate hydroxide layers is diminished by hydraulic shear forces, leading to the disaggregation and even distribution of LDH nuclei. As a result, the oriented growth of individual crystals along the horizontal plane becomes predominant, leading to a high surface charge density of the hydroxide sheets and preventing their stacking. The electron microscope virtual proofs showed that the particles had a well-defined circular shape with a thickness of about 2-3 nm. Afterward, for the first time, LDH nanosheets were used to prepare LDH nanocontainers loaded with 2-benzothiazolythio-succinic acid (BTSA) by anion exchange. The incorporation of BTSA into the interlayer region and the emission behavior of the inhibitor were investigated. These results indicate that the prepared nanosheets can be utilized as effective nanocontainers for organic inhibitor loading and anti-corrosion application.

Self-assembled polyoxovanadate-intercalated layered double hydroxide nanosheets hybridized with graphene oxide for extrinsic supercapacitors

POV intercalated LDH hybridized with GO increases basal spacing, forming a porous structure and improving conductivity. This nanoarchitecture, with expanded surface area and abundant redox sites, provides exceptional electrochemical activity.