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•A 3D hydrangea-like ZnCo2O4/NiCoGa-layered double hydroxide@polypyrrole core–shell heterostructure was successfully constructed.•Density functional theory (DFT) calculations were ...adopted to authenticate the charge redistribution at the heterointerfaces.•ZnCo2O4/NiCoGa-layered double hydroxide@polypyrrole exhibits satisfactory electrochemical performance for supercapacitors.
Rationally constructing advanced battery-type electrodes with hierarchical core–shell heterostructure is essential for improving the energy density and cycling stability of hybrid supercapacitors. Herein, this work successfully constructs hydrangea-like ZnCo2O4/NiCoGa-layered double hydroxide@polypyrrole (denoted as ZCO/NCG-LDH@PPy) core–shell heterostructure. Specifically, the ZCO/NCG-LDH@PPy employs ZCO nanoneedles clusters with large open void space and rough surfaces as the core, and NCG-LDH@PPy composite as the shell, comprising hexagonal NCG-LDH nanosheets with rich active surface area, and conductive PPy films with different thicknesses. Meanwhile, density functional theory (DFT) calculations authenticate the charge redistribution at the heterointerfaces between ZCO and NCG-LDH phases. Benefiting from the abundant heterointerfaces and synergistic effect among different active components, the ZCO/NCG-LDH@PPy electrode acquires an extraordinary specific capacity of 381.4 mAh g−1 at 1 A g−1, along with excellent cycling stability (89.83% capacity retention) after 10,000 cycles at 20 A g−1. Furthermore, the prepared ZCO/NCG-LDH@PPy//AC hybrid supercapacitor (HSC) exhibits a remarkable energy density (81.9 Wh kg−1), an outstanding power density (17,003.7 W kg−1), and superior cycling performance (a capacitance retention of 88.41% and a coulombic efficiency of 93.97%) at the end of the 10,000th cycle. Finally, two ZCO/NCG-LDH@PPy//AC HSCs in series can light up a LED lamp for 15 min, indicating its excellent application prospects.
Novel layered double hydroxides (LDHs) based coatings developed in-situ on aluminum alloys are recognized to provide the substrate with improved corrosion protection. LDH layers have gained prominent ...attention due to their barrier properties and ions exchange capability, together with compositional flexibility and low environmental impact. In this work, diverse MgAl LDHs layers are developed on AA5005 as a surface conversion treatment prior to applying an acrylic clearcoat. The work aims to assess the potential LDH layers of to improve the filiform corrosion (FFC) resistance of the AA500 substrate. The effect of the synthesis time and the presence of urea on the FFC susceptibility are investigated. The performance of the different synthesis conditions was compared and shown to be more effective to increase FFC resistance when well-defined crystals are formed. The findings suggest that MgAl-LDHs mitigate the extent of filiform corrosion of acrylic paint coated AA5005. The FFC inhibition was found to be qualitatively proportional to the pitting potential measured over the LDHs conversion layers.
Owing to its earth abundance, low kinetic overpotential, and superior stability, NiFe‐layered double hydroxide (NiFe‐LDH) has emerged as a promising electrocatalyst for catalyzing water splitting, ...especially oxygen evolution reaction (OER), in alkaline solutions. Unfortunately, as a result of extremely sluggish water dissociation kinetics (Volmer step), hydrogen evolution reaction (HER) activity of the NiFe‐LDH is rather poor in alkaline environment. Here a novel strategy is demonstrated for substantially accelerating the hydrogen evolution kinetics of the NiFe‐LDH by partially substituting Fe atoms with Ru. In a 1 m KOH solution, the as‐synthesized Ru‐doped NiFe‐LDH nanosheets (NiFeRu‐LDH) exhibit excellent HER performance with an overpotential of 29 mV at 10 mA cm−2, which is much lower than those of noble metal Pt/C and reported electrocatalysts. Both experimental and theoretical results reveal that the introduction of Ru atoms into NiFe‐LDH can efficiently reduce energy barrier of the Volmer step, eventually accelerating its HER kinetics. Benefitting from its outstanding HER activity and remained excellent OER activity, the NiFeRu‐LDH steadily drives an alkaline electrolyzer with a current density of 10 mA cm−2 at a cell voltage of 1.52 V, which is much lower than the values for Pt/C–Ir/C couple and state‐of‐the‐art overall water‐splitting electrocatalysts.
The sluggish hydrogen evolution reaction (HER) kinetics on a NiFe layered double hydroxide (LDH) are substantially sped up in a novel approach by tailoring its water dissociation active sites in alkaline solutions. The resultant Ru‐doped NiFe‐LDH nanosheet exhibits a greatly enhanced HER activity in alkaline solution, which is superior to those of Pt/C and state‐of‐the‐art Pt‐free electrocatalysts.
The development of a high‐performance electrocatalyst for oxygen evolution reaction (OER) is imperative but challenging. Here, a partial sulfidation route to construct Ni2Fe‐LDH/FeNi2S4 ...heterostructure on nickel foam (Ni2Fe‐LDH/FeNi2S4/NF) by adjusting the hydrothermal duration is reported. The heterostructures afford abundant hydroxide/sulfide interfaces that offer plentiful active sites, rapid charge and mass transfer, favorable adsorption energy to oxygenated species (OH− and OOH) evidenced by the density functional theory calculations, which synergistically boost the alkaline water oxidation. In the 1.0 m KOH solution, Ni2Fe‐LDH/FeNi2S4/NF exhibits an excellent OER catalytic activity with a much smaller overpotential (240 mV) to reach the current density of 100 mA cm−2 than single‐phase Ni2Fe‐LDH/NF (279 mV) or FeNi2S4/NF (271 mV). More impressively, 2000 cycles of cyclic voltammetry scan for water oxidation results in the formation of a sulfate layer over the catalyst. The corresponding post‐catalyst demonstrates better OER activity and durability than the initial one in the alkaline simulated seawater electrolyte. The post‐Ni2Fe‐LDH/FeNi2S4/NF delivers smaller overpotential (250 mV) at 100 mA cm−2 and longer stability time than the original form (260 mV). The post‐formed sulfate passivating layer is responsible for the outstanding corrosion resistance of the salty‐water oxidation anode since it can effectively repel chloride.
Ni2Fe‐LDH/FeNi2S4/NF is prepared by a partial sulfidation of Ni2Fe‐LDH/NF. Abundant hydroxide/sulfide interfaces boost the alkaline water oxidation. Impressively, cyclic voltammetry activation results in the formation of a sulfate layer that largely enhances the corrosion resistance of the catalyst in the alkaline salty‐water electrolytes.
Hydrothermally prepared layered double hydroxide (LDH) coating is unfavorable to large-size magnesium alloy parts. Herein, PO43−- and OH−-intercalated MgAl-LDH coatings with good corrosion resistance ...and strong adhesion were first prepared under relatively mild conditions. The optimal coating displays an exceptionally low corrosion current density (5.68 nA cm−2), a high charge transfer resistance (831.3 kΩ cm2), and negligible morphological variation without visual corrosion after 15 days of neutral salt spray exposure. The superior long-term protection is attributed to the intelligent release of PO43− and formed phosphate depositions with extremely low solubility product constant to effectively self-repair the micro-defects.
•PO43− and OH− co-intercalated layered double hydroxide (LDH) coating was obtained.•The coating was prepared under atmospheric pressure throughout the process.•The optimal coating shows corrosion protection comparable to a hydrothermal method.•PO43−-intercalation enhances the LDH coating’s long-term corrosion protection.•The corrosion protection mechanism of the PO43−-inserted LDH coating is discussed.
Layered double hydroxides are members of an anionic clay family, characterised by unique two-dimensional layered structures and lend versatility in various applications. These biocompatible compounds ...have the potential to get intercalated with biological compounds and physico-chemically adsorbed onto organic molecules. Thus, making them important candidates for pharmaceutical and biomedical purposes. This study aims to synthesise, characterise and investigate the cellular toxicity interactions of Mg–Al LDH towards the mouse fibroblast L929 cell line. The Mg–Al LDH was synthesized by a meticulous process of co-precipitation followed by the hydrothermal method to ensure a well-defined and stable structure for suitable biological application. Characterisation techniques like Dynamic Light Scattering, Zeta potential, Scanning Electron Microscopy, Fourier transform infrared, and X-ray diffraction analysis were employed to provide deeper insights into the physiochemical properties and structural integrity of the synthesized Mg–Al LDH. The investigation of cellular interactions with the L929 fibroblast cell line served to assess the biocompatibility and potential cytotoxic effects of Mg–Al LDH. This was observed by assessing the morphological changes and evaluating the cytotoxic effects of Mg–Al LDH by utilising various techniques like phase contrast microscopy, fluorescent staining, and Giemsa staining. The cellular metabolic activity was assessed by MTT assay, and the subcellular lysosomal alteration was examined using the fluorescent staining method by the acridine orange staining. The dose-dependent response observed in the cellular interaction underscores the importance of dosage considerations for potential biomedical applications. By elucidating the dose-response relationship, this study contributes valuable information for the safe and effective usage of LDH in biomedical contexts.
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•Synthesis of Mg–Al Layered Double Hydroxide.•Physicochemical characterization of Mg–Al LDH.•Interaction of Mg–Al LDH and L929 cells.•Determination of viability using MTT assay.•Study of morphological changes on exposure of LDH.
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•Layered double hydroxides (LDH) were embedded in PVA and SA, cross-linked by La3+.•La3+ also modified PS-La-LDH hydrogels to improve the phosphate adsorption.•The adsorption capacity ...of PS-La-LDH is 34.2 mg/g, which converted to 91.2 mg/g LDH.•PS-La-LDH removes P by electrostatic adsorption, ligand exchange and ion exchange.
Lanthanum modified compounds and Layered double hydroxides (LDH) are promising adsorbents for phosphate. However, the nano-scale LDH is challenging to separate, and conventional immobilization methods weaken the adsorption performance. With the affinity between metal ions and phosphate, polyvinyl alcohol/metal ions sodium alginate (PS-M−LDH) hydrogel beads for the improvement of phosphate removal were prepared by in-situ crosslinking with different metal ion (M) solutions. Through screening, the PS-M−LDH crosslinked by La (PS-La-LDH) has the preferable phosphate adsorption performance. The phosphate adsorption behavior of PS-La-LDH hydrogel was further investigated. Results showed that the adsorption process of phosphate by PS-La-LDH hydrogel was in accordance with the pseudo-second-order kinetic model and Freundlich model. The maximum experimental adsorption capacity of PS-La-LDH was 34.2 mg P/g, converting to an equivalent LDH of 91.2 mg P/g LDH, which was 1.6 times of pristine LDH powder (58.0 mg P/g LDH). The removal of phosphate by PS-La-LDH performed well at a wide range of pH 3 ∼ 8. PS-La-LDH showed selective adsorption to phosphate with the existence of competing anions (Cl-, NO3–, and SO42–). The phosphate adsorption by PS-La-LDH hydrogel only reduced 16.57 % when the concentration of SO42– was increased to 2882 mg/L. SEM, XRD, FTIR, and XPS results showed that the electrostatic interaction, ligand exchange, and ion exchange jointly facilitated the adsorption of phosphate.
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•Fe/Mg-LDH was dispersed on commercial high surface area Douglas fir biochar (LDHBC).•LDHBC phosphate capacity (1279 mg/g) was six-fold greater than LDH (234 mg/g).•1 M NaOH stripped ...phosphate but reduced following P uptake.•Ion-exchange, chemisorption and precipitation mechanisms were considered.
Phosphate is a primary plant nutrient, serving integral role in environmental stability. Excessive phosphate in water causes eutrophication; hence, phosphate ions need to be harvested from soil nutrient levels and water and used efficiently. Fe-Mg (1:2) layered double hydroxides (LDH) were chemically co-precipitated and widely dispersed on a cheap, commercial Douglas fir biochar (695 m2/g surface area and 0.26 cm3/g pore volume) byproduct from syn gas production. This hybrid multiphase LDH dispersed on biochar (LDHBC) robustly adsorbed (~5h equilibrium) phosphate from aqueous solutions in exceptional sorption capacities and no pH dependence between pH 1–11. High phosphate Langmuir sorption capacities were found for both LDH (154 to 241 mg/g) and LDH-modified biochar (117 to 1589 mg/g). LDHBC was able to provide excellent sorption performance in the presence of nine competitive anion contaminants (CO32–, AsO43−, SeO42−, NO3–, Cr2O72−, Cl−, F−, SO42−, and MoO42−) and also upon remediating natural eutrophic water samples. Regeneration was demonstrated by stripping with aqueous 1 M NaOH. No dramatic performance drop was observed over 3 sorption-stripping cycles for low concentrations (5 ppm). The adsorbents and phosphate-laden adsorbents were characterized using Elemental analysis, BET, PZC, TGA, DSC, XRD, SEM, TEM, and XPS. The primary sorption mechanism is ion-exchange from low to moderate concentrations (10–500 ppm). Chemisorption and stoichiometric phosphate compound formation were also considered at higher phosphate concentrations (>500 ppm) and at 40 °C. This work advances the state of the art for environmentally friendly phosphate reclamation. These phosphate-laden adsorbents also have potential to be used as a slow-release phosphate fertilizer.
Nanocontainers encapsulating corrosion inhibitors are commonly incorporated into organic coatings to enable self-healing effects, thereby ensuring long-term anticorrosion performance. In this study, ...a novel dual corrosion inhibitor-loaded self-healing nanocontainer with core-shell structure was proposed for fabricating composite waterborne epoxy coatings with both active and passive corrosion prevention properties.
The nanocontainer, named BTA-ZIF-8@LDH-Mo, was synthesized through the in-situ growth of molybdate-intercalated ZnAl layered double hydroxide (LDH-Mo) on the surface of 1H-benzotriazole-inbuilt zeolitic imidazolate framework (BTA-ZIF-8). Potentiodynamic polarization results showed that the Icorr of bare Q235 carbon steel immersed in a 3.5 wt% NaCl solution decreased from 4.658 × 10−6 A/cm2 to 1.274 × 10−6 A/cm2 after introducing BTA-ZIF-8@LDH-Mo nanocontainers, resulting in a superior corrosion inhibition efficiency of 72.65 %. Electrochemical impedance spectroscopy further demonstrated that the |Z|f=0.01Hz of epoxy coating doped with BTA-ZIF-8@LDH-Mo reached 4.24 × 109 Ω·cm2 after 42 d of immersion in 3.5 wt% NaCl solution, approximately 30 times higher than that of pure EP coating. Moreover, investigations on artificially scratched coatings indicated that the incorporation of BTA-ZIF-8@LDH-Mo nanocontainers effectively mitigated the corrosion process by forming an inhibiting layer on the metal substrate that impeded the corrosion process. The dual corrosion inhibitor strategy relies on the synergistic action of BTA pre-loaded in ZIF-8 nanoparticles and molybdate (MoO42-) intercalated in LDH interlayers for active corrosion protection. Additionally, the nanocontainers enhance passive protection by elongating the diffusion paths of corrosive media and trapping chloride ions. This nanocontainer design offers a facile strategy for fabricating a smart coating with the excellent anticorrosion properties.
•BTA-ZIF-8@LDH-Mo core-shell structured nanocontainers were prepared.•Resulted nanocontainers exhibited effective dual inhibitor release.•The nanocontainers provide both active and passive corrosion protection for waterborne epoxy coating.
