Structure Of LDH Research Articles

Preparation of La-doped NiAl-LDH with boosted electron transfer for the enhanced photocatalytic activity of tetracycline: Performance evaluation, degradation pathway, and mechanism insight

Developing a photocatalysis-based system is an effective strategy for removing antibiotics. Herein, La-doped NiAl-layered double hydroxides (LaNiAl-LDH) photocatalyst was synthesized using a chemical co-precipitation-hydrothermal method. The prepared samples were characterized by various advanced analyses and investigated for the photocatalytic degradation of tetracycline (TC). The crystalline phase and functional groups of the synthesized samples were successfully confirmed by XRD and FTIR analyses. By doping La into NiAl-LDH structure, the band gap was reduced from 3.01 eV to 2.57 eV, indicating higher photocatalytic activity of 1% LaNiAl-LDH. The surface morphology of the synthesized samples shows the formation of nanosheets in the structure of LDH. Under the optimum status ([TC]0 = 10 mg/L, [1% LaNiAl-LDH] = 0.2 g/L, and pH = 6), the photocatalytic activity of 1% LaNiAl-LDH (84.85%) was higher than NiAl-LDH (71.52%) within 90 min reaction. This difference can be attributed to the presence of La sites in 1% LaNiAl-LDH which act as electron-transfer mediators, leading to a significant improvement in the separation of photogenerated charge carriers. The effect of the addition of various scavengers was evaluated. Moreover, using the o-phenylenediamine (OPD), and photoluminescence (PL) analysis, the formation of •OH radicals was supported. The higher charge-transfer efficiency of 1% LaNiAl-LDH was confirmed by photoelectrochemical analysis. Furthermore, the reusability, stability, and degradation pathway of the as-synthesized nanocomposite were systematically examined. This work presents guidance for applying doped LDH-based materials in photocatalysis and promising applications in wastewater remediation.

Promotion of the oxygen evolution reaction by introducing MoS2 into CoFe LDH via improved charge transfer and electrocatalytical activity

It is of great significance to investigate economical and efficient non-noble metal electrocatalysts for improving the kinetics of slow oxygen evolution reaction (OER). This study presents a hydrothermal method employed for the synthesis of MoS2@CoFe LDH/NF (NF: nickel foam) electrocatalysts. The layered structure of CoFe LDH offers abundant active sites for OER. The combined effects of MoS2 nanoparticles and LDH structure elevate the catalytic performance of OER. When the current density of 10 mA cm−2, the overpotential and Tafel slope were measured to be 234 mV and 87.68 mV dec-1. Moreover, the current density remained at 90 % of its initial value for 18 h in an alkaline solution, demonstrating excellent stability. Consequently, this study provides valuable insights for designing nanoparticle-LDH heterostructures to achieve resultful OER in practical applications.

LDH nanocrystal@amorphousness core–shell structure derived from LDH → LDO transformation: Synergistically enhanced energy stored for LIBs anode

With the emergence of advanced electronics and appliances, there is a growing demand for high power/energy density and cyclic stability of Li-ion batteries (LIBs), which stimulates the development of high-performance electrode materials. Herein, we proposed and implemented a novel strategy of employing the LDH → LDO intermediate-transformation amorphization to improve the performance of LDH as LIBs anode. In this work, flower-like NiCo-LDH nanoparticles (LDHRT) are synthesized for the first time by co-precipitation using triethanolamine (TEA) as an alkali source and H2O2 as a size-controlling reagent. Then, the unique LDH nanocrystal@amorphousness core–shell structure was obtained by fine-tuning the heat treatment, which significantly improved the electrochemical properties of the material. The layered structure of LDH and the internal defects of the amorphous phase provide abundant transport channels and a larger accommodation space for Li+, improving the rate capability and capacity of LIBs. In addition, the surface amorphous layer and the reduced size of LDHRT nanocrystals effectively alleviate the volume effect, improving the cycling stability of the electrode material. As a result, superior capacity (1821.3 mAh g−1 at 0.1 A g−1), rate capability, and cyclic stability (∼687.7 mAh g−1 at 0.5 A g−1 after 500 cycles, with the average capacity attrition rate of 0.092 %) were achieved. The Li+ diffusion coefficient and capacity retention rate (after 300 cycles) are higher than nearly 3 orders of magnitude and 50.12 % compared to the LDHRT, respectively. This study has opened a simple, safe, and economical new avenue for developing high-performance electrode materials.

Laser induction of hierarchically micro/nanostructured CoNi-LDH/C composite for high-performance lithium-sulfur batteries

Li-S batteries suffer from limited electronic conductivity and shuttle effect of soluble LiPSs, which can hinder redox kinetics and reduce overall electrochemical performance. To solve these issues, we propose a strategy to synthesize a CoNi-layered double hydroxide/carbon composite (L-CoNi-LDH/C) through laser treatment and hydrothermal reaction. The resulting L-CoNi-LDH/C composite possesses a high specific surface area, enabling effectively anchor sulfur molecules and adsorb LiPSs. Moreover, the 2D layered structure of LDH and porous carbon framework can facilitate electron and ion transport. The Co and Ni species in the LDH structure act as catalysts, promoting the conversion of LiPSs into Li2S/Li2S2 and enhancing redox kinetics. A Li-S battery using CoNi-LDH/C as S host (S@CoNi-LDH/C) shows an initial capacity of 1574 mAh g−1 and maintains a reversible capacity of 1097 mAh g−1 after 100 cycles.

Facile preparation of AlCo-LDH/sepiolite composites as peroxymonosulfate catalysts for efficient degradation of norfloxacin: Performance, reaction mechanism and degradation pathway

In this study, AlCo-LDH/sepiolite composite catalysts were successfully prepared by a simple water bath method. In the AlCo-LDH/sepiolite composite catalyst, the nanosheet structure of LDH was uniformly immobilized on the surface of sepiolite fibers. The AlCo-LDH/sepiolite composite catalyst was proposed to activate peroxymonosulfate (PMS) to remove norfloxacin (NOR). The reaction rate constant for the degradation of NOR was investigated to be 0.3405 min−1 in the AlCo-LDH/sepiolite/PMS system, which was 2.22 times higher than that of the AlCo-LDH/PMS system. The combination of AlCo-LDH with sepiolite carriers increased the specific surface area of the catalysts, exposing more active sites and widening the distribution of surface hydroxyl groups, which resulted in a significant enhancement of the combination of AlCo-LDH with sepiolite/PMS significantly improved the degradation performance of NOR. Quenching experiments revealed that SO4•- and 1O2 played the main roles in the degradation of NOR, with both radical and non-radical pathways contributing, and the Co(III)/Co(II) redox cycle was found to be crucial for the activation of PMS to degrade NOR efficiently. In addition, the reaction mechanism and degradation pathway of NOR degradation in this system were elucidated. In conclusion, the AlCo-LDH/sepiolite composites provide a new reference for the development of environmentally friendly catalysts, and have good application prospects in activating PMS for wastewater treatment.

Fast Determination of Rutin on a Biosensor Made Using a Layered Double Hydroxide Nanocomposite Modified Electrode.

In this study, a nanocomposite of LDH/graphene/polyaniline/gold (LDH/rGO/PANI/Au) was synthesized and characterized. The results of characterization showed that the composite material preserved the layered structure of LDH. The composite was dropped onto the glassy carbon electrode and laccase was then immobilized. Electrochemical tests showed that the composite could accelerate the electron transfer between the enzyme and the electrode. The composite/laccase showed an obvious response to rutin and the optimal detection conditions were discussed. The oxidative peak current of the biosensor constructed using the modified electrode was negatively correlated with rutin in the range of 0.05-4 μg/mL. The detection limit was 0.0017 μg/mL at a signal-to-noise ratio of 3. This biosensor of rutin also possessed high sensitivity, excellent anti-interference ability, and stability. The contents of rutin in tablets, first determined using HPLC, were also detected using the sensor constructed in this research as an application, and the results were acceptable. This research here provides a facile way for the fast detection of rutin in real samples.

Binary Ni–Fe layered double hydroxide on flexible nickel foam for the wide-range voltammetric detection of fibrinogen in simulated body fluid

Fibrinogen, a circulating glycoprotein in the blood, is a potential biomarker of various health conditions. This work reports a flexible electrochemical sensor based on Ni–Fe layered double hydroxide (Ni–Fe LDH) coated on Nickel foam (Ni–Fe LDH/NF) to detect fibrinogen in simulated human body fluid (or blood plasma). The nanoflakes like morphology and hexagonal crystal structure of LDH, synthesized via urea hydrolysis assisted precipitation technique, are revealed by scanning electron microscopy (SEM) and powder x-ray diffraction (PXRD) techniques, respectively. The fabricated sensor exhibits linearity in a wide dynamic range covering the physiological concentration, from 1 ng ml−1 to 10 mg ml−1 , with a sensitivity of 0.0914 mA (ng/ml)−1(cm)−2. This LDH-based sensor is found to have a limit of detection (LOD) of 0.097 ng ml−1 and a limit of quantification (LOQ) of 0.294 ng ml−1 (S/N = 3.3). The higher selectivity of the sensor towards fibrinogen protein is verified in the presence of various interfering analytes such as dopamine, epinephrine, serotonin, glucose, potassium, chloride, and magnesium ions. The sensor is successful in the trace-level detection of fibrinogen in simulated body fluid with excellent recovery percentages ranging from 99.5% to 102.5%, proving the synergetic combination of 2D Ni–Fe layered double hydroxide and 3D nickel foam as a promising platform for electrochemical sensing that has immense potential in clinical applications.

Modified Ni-Al layer double hydroxides as nanoparticles for self-healing anti-corrosion composite coating

Corrosion is a major concern for metallic structures, leading to significant economic losses and safety risks. Self-healing coatings have recently emerged as a promising solution to mitigate corrosion issues. This research develops a novel self-healing anti-corrosion composite coating using Ni-Al double layer hydroxide (LDHs) modified with phosphate ions as inhibitor. 1 wt% of modified particles were incorporated into the polyurethane (PU) matrix to form a coating (PU-LDH-PO4) and was applied on the carbon steel substrate. Reference coating (PU-LDH-NO3) was also formed for comparison purposes. The LDH serves as a reservoir for the inhibitor, which gradually released in response to corrosion-induced damage. The inhibitor release inhibits the corrosion process and promotes the formation of a protective passive film on the metallic surface. FTIR and FE-SEM coupled with EDS confirmed the successful loading of phosphate ions in the layered structure of Ni-Al LDH. The corrosion resistance of the self-healing composite coating was evaluated by electrochemical impedance spectroscopy (EIS) and salt spray test (SST). These tests demonstrate a higher and more robust inhibition efficiency (98 %) and self-healing effect compared to the reference coating. The enhanced corrosion ability of developed modified coating can be attributed to the effective and controlled release of inhibitor ions as well as the entrapment of aggressive chloride ions (Cl−) through the ion exchange mechanism. This composite coating demonstrated enhanced corrosion resistance and self-healing properties, making it a promising candidate for applications in protecting metallic structures against corrosive environments.

Remarkable tailoring of thermal and dielectric properties of poly(vinyl alcohol) nanocomposite via hydrothermal grown ZnAl layer di hydroxide nanostructures and graphene fillers

AbstractIn this work, we have synthesized the zinc‐aluminum layered double hydroxide (ZnAl LDH) nanostructures using cost‐effective hydrothermal technique. The ZnAl LDH and graphene‐based poly(vinyl alcohol) (PVA) nanocomposites are fabricated. The crystal structure, morphology, thermal, and dielectric properties of pristine PVA and ZnAl LDH and graphene‐based PVA nanocomposites films were investigated using X‐ray diffraction, HR‐transmission electron microscopy, thermo gravimetric analysis, and impedance analyzer. HRTEM analysis reveals the hexagonal nanoplates shape‐like morphology of Zn‐Al layered double hydroxides with an average thickness of 40–50 nm and size of 400–600 nm. High thermal stability was observed from ZnAl LDH and graphene‐reinforced nanocomposite. Enhanced thermal stability of 250°C and low weight loss was observed from ZnAl LDH reinforced PVA‐based nanocomposites compared to pristine PVA. Zn‐Al LDH nanoplates‐graphene‐PVA based nanocomposites showed ultra‐high dielectric constant (ɛ′) of 794 as compared to the ZnAl LDH‐PVA nanocomposites (ɛ′ ~ 334) and pristine PVA sample (ɛ′ ~ 35). Low dielectric loss of 0.27, 0.18, 0.38 was observed for pristine PVA, ZnAl‐LDH‐PVA and ZnAl‐LDH‐graphene‐PVA nanocomposites. The large enhancement of the dielectric constant and thermal stability were discussed in terms of improved crystallinity, interfacial polarization and formation of nanodipoles in the matrix. This study reveals a significant role of LDH‐graphene‐based hybrid nanocomposites in optoelectronics, energy storage, sensors, energy conversion and thermally stable devices.Highlights Growth of highly crystalline zinc‐aluminum layered double hydroxide nanostructures. Improved thermal stability for Zn‐Al LDH‐graphene‐PVA nanocomposites. High thermal stability from ZnAl LDH‐based PVA nanocomposites. Ultra‐high dielectric constant of 794 is observed from Zn‐Al LDH nanoplates‐graphene‐nanocomposites.

Creation of a Highly Active Small Cu-Based Catalyst Derived from Copper Aluminium Layered Double Hydroxide Supported on α-Al2 O3 for Acceptorless Alcohol Dehydrogenation.

A highly dispersed carbonate-intercalated Cu2+ -Al3+ layered double hydroxide (CuAl LDH) was created on an unreactive α-Al2 O3 surface (CuAl LDH@α-Al2 O3 ) via a simple coprecipitation method of Cu2+ and Al3+ under alkaline conditions in the presence of α-Al2 O3 . A highly reducible CuO nanoparticles was generated, accompanied by the formation of CuAl2 O4 on the surface of α-Al2 O3 (CuAlO@α-Al2 O3 ) after calcination at 1073 K in air, as confirmed by powder X-ray diffraction (XRD) and Cu K-edge X-ray absorption near edge structure (XANES). The structural changes during the progressive heating process were monitored by using in-situ temperature-programmed synchrotron XRD (tp-SXRD). The layered structure of CuAl LDH@α-Al2 O3 completely disappeared at 473 K, and CuO or CuAl2 O4 phases began to appear at 823 K or 1023 K, respectively. Our synthesised CuAlO@α-Al2 O3 catalyst was highly active for the acceptorless dehydrogenation of benzylic, aliphatic, or cyclic aliphatic alcohols; the TON based on the amount of Cu increased to 163 from 3.3 of unsupported CuAlO catalyst in 1-phenylethanol dehydrogenation. The results suggested that Cu0 was obtained from the reduction of CuO in the catalyst matrix during the reaction without separate reduction procedure and acted as a catalytically active species.

Optimizing electronic structure of NiFe LDH with Mn-doping and Fe0.64Ni0.36 alloy for alkaline water oxidation under industrial current density

Optimizing electronic structure of NiFe LDH with Mn-doping and Fe0.64Ni0.36 alloy for alkaline water oxidation under industrial current density

Heterostructural NiSe-CoFe LDH as a highly effective and stable electrocatalyst for the oxygen evolution reaction.

Design and exploration of highly efficient oxygen evolution reaction (OER) electrocatalysts is an urgent task to realize the future ideals of the hydrogen economy. Non-precious metal-based nanomaterials have been widely developed as electrocatalysts to expedite reaction rate and solve the low efficiency problem of the OER. A novel nanocatalyst, NiSe-CoFe LDH, in which lamellar CoFe LDH covered the surface of NiSe, was fabricated through a simple chemical vapor deposition and hydrothermal method. The specific heterogeneous three-dimensional structure of NiSe-CoFe LDH showed impressive electrochemical performance towards the OER. When used as an OER electrocatalyst, the NiSe-CoFe LDH nanomaterial afforded an overpotential of 228 mV to attain 10 mA cm-2. Furthermore, NiSe-CoFe LDH also maintained excellent stability with negligible activity after chronopotentiometry measurement for 60 hours.

Deciphering the amplification of dual catalytic active sites of Se-doped NiV LDH in water electrolysis: a hidden gem exposure of anion doping at the core-lattice LDH framework

Selenium anion doping in the core lattice structure of NiV LDH is done for the very first time which shows excellent OER and HER performance. Polarization effect of electron-dense Se anion results optimal outcomes in Se-NiV LDH for TWS.

Constructing multi-dimensional transport pathways by mixed-dimensional fillers in membranes for efficient CO2 separation

Mixed matrix membranes (MMMs) with mixed-dimensional fillers can take simultaneously advantages of the different-dimensional materials, and they hold the potential in exhibiting excellent CO2 separation performance. In this study, the mixed-dimensional fillers of NiCo-layered double hydroxide-decorated polypyrrole nanotubes (PNT@NiCo-LDH) were synthesized and incorporated into Pebax MH 1657 (Pebax) matrix to fabricate MMMs for efficient CO2 separation. PNT@NiCo-LDH played a vital role in MMMs. PNT@NiCo-LDH can take the advantages of the tubular structure of PNT, the lamellar structure of LDH, the hollow nanocage structure of NiCo-LDH, constructing 1D/2D/3D CO2 transport pathways in MMMs, respectively. Thus, the construction of multi-dimensional (1D/2D/3D) CO2 transport pathways could synergistically improve CO2 separation performance of MMMs. Besides, the CO2-affinity groups (amino groups and hydroxyl groups) and bimetallic sites (Ni and Co) on PNT@NiCo-LDH effectively accelerated CO2 selective transport in MMMs, increasing CO2/CH4 selectivity. Therefore, the as-prepared MMMs exhibited an excellent CO2 separation performance. The Pebax/PNT@NiCo-LDH-5 MMM showed the optimum CO2 permeability of 513 ± 10 Barrer and CO2/CH4 separation factor of 39 ± 0.5. This work implied that the construction of multi-dimensional CO2 pathways by mixed-dimensional fillers were an effective strategy for efficient CO2 separation in MMMs.

Spontaneous synthesis of Ag nanoparticles decorated ZnAl layered double hydroxides for synergistically improved SERS activity

Surface enhanced Raman spectroscopy (SERS) is a rapid and ultrasensitive analytical technique. For practical applications, it is highly desirable to explore metal/semiconductor hybrid substrates, which utilize the synergistic enhancement effects of plasmons and charge transfer (CT). Herein, we successfully fabricated Ag nanoparticles decorated ZnAl LDHs nanosheets (Ag-ZnAl) by a facile one-pot solvothermal growth method and investigated the SERS performance. When 4-nitrobenzenethiol (4-NBT) was used as the probe molecule, the detection limit reaches as low as 1 × 10−10 M and the enhancement factor is 1.7 × 105. A systematic experimental study revealed that the unique structure of LDH facilitates formation of densely distributed Ag NPs with good dispersibility, providing abundant “hot spots” for electromagnetic enhancement. Moreover, Ag-ZnAl hybrid has a higher concentration of oxygen vacancies, which can promote photo-induced CT for chemical enhancement. Furthermore, first principles calculations demonstrated that Ag-ZnAl hybrid has improved adsorption ability of 4-NBT through the formation of Ag-S and NOH bonds, which can facilitate charge transfer process and increase Raman intensity of 4-NBT. This work provides an effective strategy to design easy-to-fabricated metal/semiconductor hybrids as SERS sensing platform.

Efficient Recycling Blast Furnace Slag by Constructing Ti-Embedded Layered Double Hydroxide as Visible-Light-Driven Photocatalyst.

In this work, a strategy of heat treatment-precipitation has been developed to recycle Ti-containing metallurgical solid waste by forming Ti-embedded MgAl layered double hydroxide (TMA-LDH). This facile and simple route is featured by the dedicated utilization of the composition of slag with high overall recovery efficiency. Importantly, as-obtained product exhibits visible light response distinctly different from that of pristine MA-LDH ascribed to the Fe doping inherited from initial slag. Its mesoporous nanostructure also provides more microchannels for mass and carrier transfer. As such, excellent photocatalytic activity towards degradation of tetracycline hydrochloride is achieved, and 88% removal could be obtained in 60 min. Furthermore, 44% increase in efficiency than that of Ti-excluded LDH also indicates the synergistically promoting effect of Ti incorporation. Mechanism investigation suggests that Ti incorporation regulates the electronic structure of pristine LDH with more active sites, and favors the formation of radicals with improved oxidative ability for photocatalysis.

High-content atomically distributed W(V,VI) on FeCo layered double hydroxide with high oxygen evolution reaction activity.

High-content atomically distributed W(V,VI) coordinated with O atoms as WO2 moieties anchored on FeCo layered double hydroxide (FeCo LDH) nanosheets in the structure of SAC W-FeCo LDH is obtained by a facile coprecipitation method, and it presented clearly enhanced stable OER electrocatalytic activity.

Interface engineering of FeCo LDH@NiCoP nanowire heterostructures for highly efficient and stable overall water splitting

Developing efficient and inexpensive OER electrocatalysts is a challenge for overall water splitting. Herein, the heterostructured FeCo LDH@NiCoP/NF nanowire arrays with high performance were rationally designed and prepared using an interface engineering strategy. Benefitting from the special heterostructure between FeCo LDH and NiCoP, the as-synthesized FeCo LDH@NiCoP/NF electrocatalyst exhibits outstanding OER performance with an exceptionally low overpotential of 206 mV to achieve 20 mA/cm2 current density in an alkaline electrolyte. Importantly, a cell constructed using the FeCo LDH@NiCoP/NF electrocatalyst as cathode and anode just needs a voltage of 1.48 V at 10 mA/cm2, and shows excellent stability over 80 h. Experimental and theoretical results verified that the introduction of NiCoP efficiently regulates the electronic structure of FeCo LDH, which tremendously boosts the conductivity and intrinsic catalytic activity of FeCo LDH@NiCoP/NF electrocatalyst. The present work provides guidance for the preparation of other efficient and cheap electrocatalytic materials.

Cu nanoparticles-dispersed Mg-Al layered double hydroxides as efficient catalysts for CO2 conversion with propargyl alcohols

Upgrading carbon dioxide (CO2) into valuable products is a highly promising strategy of artificial carbon cycle. In this study, a series of in situ reduced CuMgAl layered double hydroxides (R-CuMgAl-LDHs) composites were synthesized, in which Cu nanoparticles were effectively dispersed and anchored on MgAl-LDHs with formation of Cu+ and Cu0 species. The optimized R-Cu1.5Mg1.5Al1-LDH exhibited excellent catalytic performance for the carboxylative cyclization of 2-methyl-3-butyn-2-ol with CO2 (turnover number of 243) under mild conditions. The layered structure of LDH stabilized the active Cu species with high dispersion, enhancing the catalytic efficiency of this carboxylative cyclization reaction. Simultaneously, the dual-activation of both CO2 and propargylic alcohol by Cu0/Cu+ species generated on the surface of LDH contributed significantly to the catalytic efficiency enhancement. Furthermore, R-Cu1.5Mg1.5Al1-LDH catalyzed the reaction of a wide range of terminal or internal propargyl alcohols with CO2, yielding various functionalized α-alkylene cyclic carbonates. Finally, a reasonable reaction mechanism was put forward according to the comprehensive analysis.

Electronically coupled layered double hydroxide/MXene quantum dot metallic hybrids for high‐performance flexible zinc–air batteries

AbstractPrecise control of the local electronic structure and properties of electrocatalysts is important for enhancing the multifunctionality and durability of electrocatalysts and for correlating the structure/chemistry with the catalytic properties. Herein, we report electronically coupled metallic hybrids of NiFe layered double hydroxide nanosheet/Ti3C2 MXene quantum dots deposited on a nitrogen‐doped graphene surface (LDH/MQD/NG) for high‐performance flexible Zn–air batteries (ZABs). As verified from the Mott–Schottky and Nyquist plots, as well as spectroscopic, electrochemical, and computational analyses, the electronic and chemical coupling of LDH/MQD/NG modulates the local electronic and surface structure of the active LDH to provide metallic conductivity and abundant active sites, leading to significantly improved bifunctional activity and electrocatalytic kinetics. The rechargeable ZABs with LDH/MQD/NG hybrids are superior to the previous LDH‐based ZABs, demonstrating a high power density (113.8 mW cm−2) and excellent cycle stability (150 h at 5 mA cm−2). Moreover, the corresponding quasi solid‐state ZABs are completely flexible and practical, affording a high power density of 57.6 mW cm−2 even in the bent state, and in real‐life operation of tandem cells for powering various electronic devices.image