Layered Double Hydroxides Materials Research Articles

The antimicrobial synergy of polymer based nanofiber mats reinforced with antioxidants intercalated layered double hydroxides as a potential active packaging material

Perishable food post-harvest loss is a major global concern, and research is currently concentrated on creating active packaging materials. This research is focused in multiple antioxidants intercalated Layered Double Hydroxides (LDH) that are combined in one matrix, and their overall effect that defines as synergism, which successfully preserves perishable food by releasing antioxidants slowly. For this purpose, a hybrid LDH material of ascorbic-LDH (AA-LDH), salicylic-LDH (SA-LDH), and citric-LDH (CA-LDH) was synthesized, characterized and incorporate into electrospun nanofiber mat to be used as a potential active packaging material. Antioxidants intercalated Mg/Al LDH was synthesized and successfully characterized by PXRD, FTIR, XPS, Raman, SEM, and EDS. The shifts in the LDHs’ peaks in PXRD indicated the successful incorporation of antioxidants into LDH. FTIR, Raman, and XPS data clearly indicated the establishment of metal-oxygen bonds by observing the characteristic peaks. Morphological features and the layered structure were clearly observed by SEM images. Antioxidants were slowly released from the LDHs, and it was evaluated for time intervals up to 24 h. The hybrid LDH material exhibited the highest antioxidant activity with an IC50 value of 132.5 μg ml−1, where 234.1, 354.5, and 402.2 μg ml−1 were reported for ascorbic-LDH, salicylic-LDH, and citric-LDH respectively. The hybrid LDH material incorporated electrospun mats showed the best antibacterial activity against the tested bacteria and clearly evidenced the synergistic activity of the combination of the nanohybrids. It has showed a minimal bacterial growth compared to the other control samples (∼2.41 log CFU/ml). The shelf life of cherry tomatoes was studied at different physiochemical parameters with and without hybrid LDH material incorporated electrospun mats. The fabricated mat showed an extended shelf life of 42 days for cherry tomatoes, whereas the control sample showed a shelf life of 17 days. It is concluded that hybrid LDH material exhibited synergistic performance and the best antioxidant activity when comparing with mono LDH materials.

Enhancing the Performance of 2D Ni-Fe Layered Double Hydroxides by Cabbage-Inspired Carbon Conjunction for Oxygen Evolution Reactions.

Layered double hydroxide (LDH) nanosheets as one type of two-dimensional materials have garnered increasing attention in the field of oxygen evolution reaction (OER) in recent decades. To address the challenges associated with poor conductivity and limited electron and charge transfer capability in LDH materials, we have developed a straightforward one-pot synthesis method to successfully fabricate a composite material with a microstructure resembling cabbage, which encompasses NiFe-LDH and nanocarbon (referred as NiFe-LDH@C). Atomic force microscopy (AFM) and high-resolution transmission electron microscopy (HRTEM) revealed that the monolayer NiFe-LDH with a height of ~0.5-0.8 nm is uniformly distributed and closely bonded to the carbon support, leading to a significant enhancement in conductivity and facilitating faster electron and charge transfer. Moreover, the NiFe-LDH@C exhibits a substantial number of surface defect sites, which enhances the interaction with oxygen species. This dual enhancement in charge transfer and oxygen species-mediated transfer greatly improves the catalytic OER performance, which is further corroborated by theoretical calculations. Notably, the Ni10Fe6-LDH@C with the highest concentration of surface oxygen vacancies demonstrated superior water oxidation performance, surpassing commercially available RuO2 catalysts; an OER overpotential of 231 mV@10 mA cm-2 with a Tafel slope of 71 mV dec-1 was achieved.

Insights of the La promotion in CoFe-LDH as particle electrodes on degradation process of N-nitrosopyrrolidine in electrocatalytic continuous-flow system

Layered double hydroxides (LDH), as a green, easy to prepare and modify material, has been widely concerned in the field of electrochemical catalytic degradation of difficult to remove pollutants in water. In our work, modified LDH material is synthesized by doping La into the lattice of CoFe-LDH based on its unique electronic structure and large ionic radius, which is used to build the particle electrode to degrade the N-nitrosopyrrolidine (NPYR) in a three-dimensional continuous flow aerated electrocatalytic reactor. The LaCoFe-LDH particle electrodes can generate more active free radicals under electric field, which are beneficial to the degradation of pollutants. The degradation effect of NPYR in the system is satisfactory, and the removal rate reached 83.3% within 90 min. According to the results of characterization analysis, radical quenching experiment, and EPR test, La doping improves the electron transfer ability of the catalyst, which effectively accelerates the redox cycle of Fe2+/Fe3+ and Co2+/Co3+ to achieve sustainable catalysis of particle electrodes to form free radicals, thus enhancing the degradation of NPYR. The DFT calculation results of CoFeLa-LDH show that the energy required for oxygen adsorption by CoFeLa-LDH (-6.79 eV) is lower than that of CoFe-LDH (-6.08 eV), illustrating the improved adsorption properties of the material after La doping. According to the detection results of GC-MS and LC-MS, the possible degradation path of NPYR is proposed. Moreover, the toxicity of the products after degradation of NPYR is generally reduced, indicating that the system is environmentally friendly. The study provides new insights into the design of electrocatalytic materials in water treatment.

Influence of morphology and composition of spherical layered double hydroxide particles and derived mixed oxides on photocatalytic CO2 reduction

Considering the flexibility in the synthesis that allows the formation of materials with more than two metals, the present study reports the preparation of trimetallic layered double hydroxides (LDHs) having Al as structural tri-positive cation, Ti as photocatalytically active d0 transition metal and either Ni or Co as dipositive cation. In addition, these LDHs were used as precursors of the corresponding trimetallic mixed oxides (MO). LDH and MO materials in combination with Ru(bpy)3Cl2 as photosensitizer and triethanolamine as sacrificial electron donor were used as catalysts for CO2 reduction under solar light irradiation. A different product selectivity, either CH4 for Ni-LDH or CO and H2 for Co-MO, was observed with production rates for CH4 or CO that are among the highest reported for these systems. The role of the inorganic materials in the photocatalytic process was supported by transient absorption spectroscopy that revealed the quenching of the Ru(bpy)3Cl2 triplet excited state by Ni-LDH or Co-MO. An important finding was that the trimetallic Co-Ti-Al oxide with cobaltite structure is able to perform CO2 reduction in spite that the reduction potential of its conduction band is not sufficient to perform the process, evidence by photoluminescence revealing the existence of an upper electronic state responsible for the reduction. These results show the interest in screening multimetallic materials in photocatalysis due to their improved performance and diverse properties.

In Situ Fabrication of Hierarchical CuO@CoNi-LDH Composite Structures for High-Performance Supercapacitors.

Layered double hydroxide (LDH) materials, despite their high theoretical capacity, exhibit significant performance degradation with increasing load due to their low conductivity. Simultaneously achieving both high capacity and high rate performance is challenging. Herein, we fabricated vertically aligned CuO nanowires in situ on the copper foam (CF) substrate by alkali-etching combined with the annealing process. Using this as a skeleton, electrochemical deposition technology was used to grow the amorphous α-phase CoNi-LDH nanosheets on its surface. Thanks to the high specific surface area of the CuO skeleton, ultrahigh loading (̃16.36 mg cm-2) was obtained in the fabricated CF/CuO@CoNi-LDH electrode with the cactus-like hierarchical structure, which enhanced the charge transfer and ion diffusion dynamics. The CF/CuO@CoNi-LDH electrode achieved a good combination of high areal capacitance (33.5 F cm-2) and high rate performance (61% capacitance retention as the current density increases 50 times). The assembled asymmetric supercapacitor device demonstrated a maximum potential window of 0-1.6 V and an energy density of 1.7 mWh cm-2 at a power density of 4 mW cm-2. This work provides a feasible strategy for the design and fabrication of high-mass-loading LDH composites for electrochemical energy storage applications.

Effective visible light-driven binary ZnO catalyst decorated on layered double hydroxides for simultaneous photocatalytic degradation of Ciprofloxacin and Ampicillin

BackgroundThe direct use of clean solar energy to convert organic pollutants in industrial wastewater into harmful products is a viable tactic and a hot topic to save water bodies and avoid water pollution. Pharmaceutical wastewater is complicated and contains a variety of contaminants, making its treatment difficult. MethodThis study focuses on the simultaneous degradation of an aqueous solution containing a combination of contaminants, Ampicillin (AMP) and Ciprofloxacin (CIP). Using hydrothermal process, we successfully fabricated a ZnO-NiCoMn layered double hydroxide (LDH) sheet. The prepared catalyst was examined using a range of surface analytical optical techniques. Significant findingsThe ZnO-NiCoMn LDH demonstrates exceptional photocatalytic performance, as demonstrated by the maximal CIP and AMP degradation rates of 96 % and 94 % in 100 min under visible light, respectively, according to the data. ZnO-adorned NiCoMn LDH sheets exhibited a rod-like structure, as demonstrated by FE-SEM and HR-TEM. Because of the highest charge separation and superior electron (e−) transport between ZnO and NiCoMn LDH material, the binary catalyst degraded CIP and AMP by 96 % and 94 % in 100 min, respectively, more than the bare catalyst. The binary ZnO-NiCoMn LDH catalyst could withstand up to five CIP and AMP degradation cycles.

In Situ Synthesis of an Epoxy Resin Microwave Absorption Coating with Anti-Ultraviolet Aging Effects

A nanoparticle-anchored three-dimensional microsphere flower-structured layered double hydroxide (LDH) material with Fe3O4 particles was successfully prepared using simple hydrothermal and hot solvent methods. Micro-nanostructured Fe3O4@LDHs (SLF) composites balance microwave absorption, corrosion protection, and UV aging resistance. The minimum reflection loss value of SLF is −35.75 dB at 14.16 GHz, when the absorber thickness is 8 mm, and the absorption bandwidth at this frequency is up to 2.56 GHz for RL values less than −10 dB, while the LL is only 1 GHz. The SLF /EP coating has not only excellent microwave absorption performance but also excellent corrosion and UV aging resistance performance. The coating still has some anti-corrosion effect after 10 d of immersion. This work is intended as a reference for the development of new coatings with excellent microwave absorption properties as well as corrosion and UV aging resistance for wind turbine tower barrels (seaside wind power generation equipment) surfaces.

Layered Double Hydroxides Reduce the Availability of Cadmium and Lead in Soil and the Content of Cadmium and Lead in Grain

ABSTRACT Layered double hydroxides (LDHs) have excellent immobilization effects on heavy metals (HMs) in water and soil. For the first time in Hunan province, the immobilization effect of Ca-Al LDH (SR-02-02) and Mg-Al LDH (SR-02-03) for the remediation of Cd and Pb was examined in contaminated soils. With treatments of SR-02-02 at 3000 kg/ha(L2–3), the immobilization effect of available Cd and Pb was 54.74% and 20.85%; with treatments of SR-02-03 at 3000 kg/ha(L3–3), the immobilization effect of available Cd and Pb was 68.02% and 26.70%, which showed that Cd, and Pb were gradually solidified into stable oxidizable and residual state. Less HMs were absorbed by rice as a result of the immobilization effect of SR-02-02 and SR-02-03, and the concentration of Cd and Pb in the root, stem, husk, and grain of rice were also significantly reduced. In particular, under the treatment of L2–3, the content of Cd and Pb in grain decreased by 69.13% and 72.67%, respectively; under the treatment of L3–3, the content of Cd and Pb in grain decreased by 80.76% and 100%, respectively. This was because LDHs materials reacted with HMs to form Cd-OH, Pb-OH, CdAl-LDH, and Ca/Mg-O-Pb etc. which reduced the availability of HMs. In conclusion, LDHs material is a promising material for the synergistic remediation of Cd and Pb contaminated soil.

Efficient Adsorption of Methylene Blue Using a Hierarchically Structured Metal-Organic Framework Derived from Layered Double Hydroxide.

The growing concerns about environmental pollution, particularly water pollution, are causing an increasing alarm in modern society. One promising approach to address this issue involves engineering existing materials to enhance their effectiveness. A one-step solvothermal reconstruction approach was used to build an eco-friendly two-dimensional (2D) AlNiZn-LDH/BDC MOF composite. The characterizations confirm the formation of a metal-organic framework (MOF) at the layered double hydroxide (LDH) surface. The resulting synthesized material, 2D AlNiZn-LDH/BDC MOF, demonstrated remarkable efficacy in decontaminating methylene blue (MB), a model cationic dye found in water systems. The removal performance of 2D AlNiZn-LDH/BDC MOF was significantly higher than that of pristine 2D AlNiZn-LDH. This improvement shows the potential to increase the adsorption capabilities of nanoporous LDH materials by incorporating organic ligands and integrating meso-/microporosity through MOF formation on their surfaces. Furthermore, their kinetic, isothermal, and thermodynamic studies elucidated the adsorption behavior of this composite material. The results of synthesized MOF showed excellent removal efficiency (92.27%) of 10 ppm of MB aqueous solution as compared to pristine LDH. Additionally, the as-synthesized adsorbent could be regenerated for six successive cycles. This method holds promise for the synthesis of novel and highly effective materials to combat water pollution, laying the groundwork for potential advancements in diverse applications.

Thermal Evolution of NiFe-NO3 LDH and Its Application in Energy Storage Systems

In this work, the performances of nickel iron layered double hydroxides (LDH) with the nitrate anion at the interlayer (NiFe-NO3) for the manufacture of anodes for lithium-ion batteries have been tested before and after its sintering at different temperatures. After synthesis, the material was thermally analyzed in a range 30–1250 °C, showing a mass loss occurring in three different consecutive steps leading to a total mass decrease of ~30 mass%. Following thermogravimetric analysis (TGA), four samples were prepared by annealing at four different temperatures: one of the four did not undergo a thermal treatment (NiFe-0), while the remaining three were annealed at 250 °C, 360 °C, and 560 °C for 6 h (NiFe-250, NiFe-360, and NiFe-560). All materials where completely characterized via FE-SEM, PXRD, and FT-IR. The pristine LDH material showed some structural and compositional changes for growing temperatures, starting from the typical turbostratic hexagonal structure through a mixture of amorphous metal oxides and finally to the stoichiometric oxides FeNi2O4 and NiO. The as-obtained materials were mixed with carbon black (C65) and sodium alginate and tested as electrodes in Swagelok half cells in LP30 vs. metallic Li to perform CV and GCPL analysis. The electrochemical tests showed that the performances of NiFe-0, both in terms of stability and specific capacity, are not so different from the one of the NiFe-560, even if the Ni mass% in the former is lower than in the NiFe-560. This phenomenon could be explained by assuming a combined mechanism of reaction involving both intercalation and conversion.

Construction of Ni2P@NiCo-BLDH nanocomposite with hierarchical porous structure on nickel foam as advanced oxygen evolution electrocatalyst

The fabrication of two-dimensional layered double hydroxides (LDHs) materials still faces great challenges, particularly in achieving precise modulation of lamellar metals and interlayer anions for electrocatalytic oxygen evolution reaction (OER). Herein, a hierarchical porous nanocomposite assembled by foam nickel (NF) supported borate anions incorporated bimetallic NiCo hydrotalcite (NiCo-BLDH) on the surface of nickel phosphide sheets (NF/Ni2P @ NiCo-BLDH) is prepared through the NF in-situ phosphating and electrodeposition approach as an electrocatalyst for achieving superior OER catalysis. In this design, introducing multi-phase and incorporated borate anions into LDHs can regulate their structure and properties, creating unique active sites and enhancing the adsorption efficiency of OH- to effectively improve the OER activity. Remarkably, the NF/Ni2P @ NiCo-BLDH electrode shows a low overpotential of 293 mV at 100 mA cm−2 for OER and a Tafel slope of 108.3 mV dec−1 in a 1.0 M KOH medium, surpassing most previously reported NiCo-based catalysts. Nevertheless, the NF/Ni2P electrode exhibits a lower overpotential for the hydrogen evolution reaction (HER) in a 1.0 M KOH medium compared to the NF/Ni2P @ NiCo-BLDH electrode. This work not only advances the catalytic activity of the NiCo-LDH-based materials in OER but also provides a new idea for large-scale electrocatalytic water splitting applications.

Acetaminophen Removal in Aqueous Solutions via Enhanced Fenton-Like Degradation by Copper-Nickel Based Layered Double Hydroxides

Layered double hydroxides (LDH) exhibit macromolecular behavior due to their layered structure, providing unique properties that make them suitable for various applications. Their crystal structure allows for intercalation of various species, demonstrating excellent thermal stability and mechanical strength. Synthesis methods, such as co-precipitation, ion exchange, and hydrothermal techniques, enable the preparation of well-defined LDH macromolecules with tailored characteristics. These materials find applications in catalysis, drug delivery systems, environmental remediation processes, and energy storage devices. Our research described here an LDH material based on nickel, copper, and aluminum was synthesized, characterized and used as a catalyst for the oxidation of Acetaminophen (Ac) using H2O2. Our materials were created using the co-precipitation process at a constant pH. Fourier Transform infrared spectroscopy (FTIR), Raman spectroscopy (RAMAN), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy-Dispersive X-ray Spectroscopy (EDS) were used to characterize the synthesized material. The material was crystalline and devoid of contaminants, according to the characterization. The CuNiAl-CO3 material was used to catalyze the elimination of the Ac (1 g.L−1) from an aqueous solution. The amount of the LDH, the molar ratio (oxidant/pollutant), the temperature, and the pH were among the experimental factors that were modified to get superior results. The kinetic analysis revealed that using 3 g L−1 of LDH with a molar ratio (oxidant/pollutant) of 2.5 for 3 h at room temperature and without modification of the pH of the solution resulted in a complete degradation of the Ac, and that our LDH performed best in acidic conditions.

In Situ Construction of NiCoMn-LDH Derived from Zeolitic Imidazolate Framework on Eggshell-Like Carbon Skeleton for High-Performance Flexible Supercapacitors.

Active compounds based on LDH (ternary layered double hydroxide) are considered the perfect supercapacitor electrode materials on account of their superior electrochemical qualities and distinct structural characteristics, and flexible supercapacitors are an ideal option as an energy source for wearable electronics. However, the prevalent aggregation effect of LDH materials results in significantly compromised actual specific capacitance, which limits its broad practical applications. In this research, a 3D eggshell-like interconnected porous carbon (IPC) framework with confinement and isolation capability is designed and synthesized by using glucose as the carbon source to disperse the LDH active material and enhance the conductivity of the composite material. Second, by constructing NiCoMn-LDH nanocage structure based on ZIF-67 (zeolitic imidazolate framework-67) at the nanometer scale the obtained IPC/NiCoMn-LDH electrode material can expose more active sites, which allows to achieve excellent specific capacitance (2236 F g-1/ 310.6 mAh g-1 at 1 A g-1), good rate as well as the desired cycle stability (85.9% of the initial capacitance upon 5000 cycles test). The constructed IPC/NiCoMn-LDH//IPC ASC (asymmetric supercapacitor) exhibits superior capacitive property (135 F g-1/60.1 mAh g-1 at 0.5 A g-1) as well as desired energy density (40Wh kg-1 at 800W kg-1).

Intercalated Redox-Active Anions in Layered Double Hydroxides: Toward New Electrode Designs

Layered Double Hydroxides (LDHs) are a versatile class of 2D materials, which consist of layered di- and trivalent metal cation hydroxides with intercalated anions (1). They are used in many applications including energy storage electrodes, water purification or drug delivery (2, 3).In this new study, Anthraquinone-2-sulfonate (AQS) intercalated in the LDH structure of Mg2Al(OH)6, has been investigated and a charge capacity of 100 mAh g-1 has been measured. However, the dissolution of reduced AQS into the aqueous electrolyte occurs from the first reduction leading to a drastic capacity fade upon cycling.To get around the dissolution issue, we synthesize a new intercalated LDH using ferrocene as the redox active moiety. Electrodes with this new LDH material Mg2Al(OH)6-Fc (Figure 1A) showed more stable cycling when used in combination with aqueous or organic electrolytes. However, the most significant increase in cycle life was achieved by operating this electrode in highly concentrated, highly viscous ionic liquid based electrolytes such as Pyr13TFSI. Over 97 % capacity retention was achieved after 200 cycles with a coulombic efficiency close to 100 % (Figure 1B). The higher stability of redox active anions working at positive redox potentials like ferrocene in the LDH structure is a key parameter to improve cycling ability. Moreover, the limited solubility of the intercalated redox anions into the high concentrated ionic liquid electrolyte is also a key factor for improving cycle life of this new electrode.Figure 1: A) Schematic structure of Mg2Al(OH)6-Fc, C) Improved cycling stability of Mg2Al(OH)6-Fc based electrodes in ionic liquid electrolyte Pyr13TFSI. Figure 1

Influence of alkaline sources for the electrochemical performance of NiCo layered double hydroxide nanostructures

The morphology and composition of nanostructures play important role in their electrochemical properties. Herein, NiCo layered double hydroxide (LDH) nanostructures were prepared by hydrothermal method with NaOH, urea and ammonia as alkaline sources, respectively. The types of alkaline can affect the morphology of the obtained NiCo LDH nanostructures. Compared with the NaOH as alkaline source, NiCo LDHs with urea and ammonia as alkaline sources exhibit obvious nanoflower structure. And the electrode corresponding to ammonia has the highest specific capacity (1498.98 F/g) at a current density of 1 A/g. And the dosage of ammonia was also influenced the composition of the obtained NiCo LDH nanostructures. Moderate ammonia dosage (0.9 mL) would ensure the purity of NiCo LDH, and achieve high specific capacity and high retention rate (82.9 %) at high current density (10 A/g). These obtained results can provide a new idea and sight for the promotion of the related electrochemical devices based on NiCo LDH materials.

"On-The-Fly" Synthesis of Self-Supported LDH Hollow Structures Through Controlled Microfluidic Reaction-Diffusion Conditions.

Layered double hydroxides (LDHs) are a class of functional materials that exhibit exceptional properties for diverse applications in areas such as heterogeneous catalysis, energy storage and conversion, and bio-medical applications, among others. Efforts have been devoted to produce millimeter-scale LDH structures for direct integration into functional devices. However, the controlled synthesis of self-supported continuous LDH materials with hierarchical structuring up to the millimeter scale through a straightforward one-pot reaction method remains unaddressed. Herein, it is shown that millimeter-scale self-supported LDH structures can be produced by means of a continuous flow microfluidic device in a rapid and reproducible one-pot process. Additionally, the microfluidic approach not only allows for an "on-the-fly" formation of unprecedented LDH composite structures, but also for the seamless integration of millimeter-scale LDH structures into functional devices. This method holds the potential to unlock the integrability of these materials, maintaining their performance and functionality, while diverging from conventional techniques like pelletization and densification that often compromise these aspects. This strategy will enable exciting advancements in LDH performance and functionality.

Enhanced Ion Transport Through Mesopores Engineered with Additional Adsorption of Layered Double Hydroxides Array in Alkaline Flow Batteries.

Efficient mass transfer in electrodes is essential for the electrochemical processes of battery charge and discharge, especially at high rates and capacities. This study introduces a 3D electrode design featuring layered double hydroxides (LDHs) nanosheets array grown in situ on a carbon felt surface for flow batteries. The mesoporous structure and surface characteristic of LDH nanosheets, especially, the hydroxyl groups forming a unique "H-bonding-like" geometry with ferrous cyanide ions, facilitate efficient adsorption and ion transport. Thus, the designed LDHs electrode enables the alkaline zinc-iron flow battery to maintain a voltage efficiency of 81.6% at an ultra-high current density of 320mA cm-2, surpassing the values reported in previous studies. The energy efficiency remains above 84% after 375 cycles at a current density of 240mA cm-2. Molecular dynamics simulations verify the enhanced adsorption effect of LDH materials on active ions, thus facilitating ion transport in the battery. This study provides a novel approach to improve mass transport in electrodes for alkaline flow batteries and other energy storage devices.

Magnesium-induced evolution of micromorphology on layered double hydroxides for enhanced hybrid supercapacitors

Layered double hydroxide (LDH) materials have demonstrated great potential in the application of supercapacitors by virtue of high theoretical specific capacity, large specific surface area, ease of fabrication and environmentally benign nature. Nevertheless, the issue of worse electrical conductivity and terrible structural stability severely constrains the practical application of LDH materials in the next-generation high-performance energy supply systems. Morphology regulation and element doping have been proved to be two effective pathways to boost the electrochemical performance of materials. In this work, a novel magnesium-doped nickel cobalt layered double hydroxides (NiCoMg-LDH) has been feasibly synthesized on flexible carbon cloth after introducing small amounts of magnesium ions into NiCo-LDH, which contributes to the evolution of micromorphology from pure nanosheets of NiCo-LDH to 3D nanosphere clusters of NiCoMg-LDH. Although magnesium ions make no direct and great capacity contribution unlike nickel ions and cobalt ions possessing mixed valence states, their successful introduction does play a vital role in regulating and controlling the micro-morphology of the as-fabricated NiCoMg-LDH material, and thus the electrochemical characteristics of the NiCoMg-LDH electrode can be successfully improved in an indirect pattern. Compared with NiCo-LDH electrode, NiCoMg-LDH electrode demonstrates much more remarkable electrochemical properties in the respect of specific capacity, rate performance and cycle life. Additionally, the aqueous hybrid supercapacitor (AHSC) NiCoMg-LDH//AC demonstrates a high gravimetric specific energy of 29.3 Wh kg−1 at 750 W kg−1 as well as a satisfactory cyclic lifespan of enduring 5000 CV scans without capacity decay. The facile fabrication and remarkable electrical performance enable this AHSC device to be an appropriate candidate with enormous potential for practical applications.

Facile synthesis of N-doped NiCo-LDH nanowire with rich oxygen vacancies by nonthermal plasma for high-performance asymmetric capacitor electrode

Layered double hydroxides (LDHs) have been served as potential pseudo-capacitive materials, especially for high-performance supercapacitors. However, the characteristics like limited capacitance, poor conductivity, and stability of LDHs severely confine their extensive applications for future energy-storage devices. It is urgent to seek a new and simple method to modify LDH materials, to improve its electrochemical performance and apply it to supercapacitors. Herein, a facile in-situ non-thermal plasma (NTP) treatment is conducted to modify NiCo-LDH nanowires for better electrochemical performance, resulting from the introduction of N-doping and oxygen vacancies by N2 NTP. All these instructive synergies provide the optimum electrode (P-NiCoNW/CC-150) after the NTP treatment under the power of 150 W with outstanding capacitance performance of 4320 mF/cm2 at 2 mA/cm2, and superior cycling stability along with capacitance retention of 117.3 %. Most importantly, an asymmetric supercapacitor device is assembled, employing P-NiCoNW/CC-150 and oxidized carbon cloth as cathode and anode electrodes respectively, exhibiting a particularly high energy density of 364 μWh/cm2 when the power density is 4505 μW/cm2. This work confirms a feasible and green NTP method to synthesize high-performance electrodes for practical applications in future energy-storage devices but not limited to supercapacitors.

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.