NiCo-layered Double Hydroxide Research Articles

In Situ Tracking of Water Oxidation Generated Nanoscale Dynamics in Layered Double Hydroxides Nanosheets.

Layered double hydroxides (LDHs) are potential catalysts for water oxidation, and it is recognized that they undergo dynamic evolution during the operation. However, little is known about the interfacial behaviors at the nanoscale under working conditions nor the underlying effects on electrocatalytic performance. Herein, using electrochemical atomic force microscopy, we in situ visualize the heterogeneous evolution of LDH nanosheets during oxygen evolution reaction (OER). By further combining density functional theory calculations, we elucidate the origin of the heterogeneous dynamics and their impact on the OER efficiency. Our findings demonstrate that NiCo LDHs transform to the catalytically active NiCoOx(OH)2-x phase during OER, and the redox transition between is accompanied by compressive and tensile strain, leading to in-plane contraction and reversible expansion of the nanosheets. Nonisotropic strain and out-of-plane strain relaxation due to defects and interparticle interactions result in cracking and wrinkling in the nanostructure, which is responsible for the partial activation and long-term deterioration of LDH electrocatalysts toward the OER. With this knowledge, we suggest and validate that engineering defects can precisely tune these dynamic behaviors, improving the OER activity and stability among LDH-based electrocatalysts.

Preparation and capacitance performance of NiCo layered double hydroxide by multi-step constant current electrodeposition method

In comparison with single-step electrodeposition, multi-step electrodeposition for electrode preparation is more effective in releasing internal stresses, utilizing the highly efficient deposition time at the beginning of the electrodeposition, improving deposition efficiency, and producing adhesive-free high-performance electrodes with controllable mass. In this paper, NiCo layered double hydroxide (NiCo-LDH) with similar mass was successfully deposited by a two-electrode constant-current electrodeposition method using nickel foam as the substrate through different electrodeposition steps. A comparative study was conducted on the effects of NiCo-LDH deposition steps on the morphology, total deposition time, and electrochemical performance of NiCo-LDH samples. The results show that the mass of NiCo-LDH grown on foam nickel is similar when the number of deposition steps is from 1 to 6 at 12–13 mg, the coating of foam nickel substrate became more uniform. The total deposition time has decreased from 2550 s for 1-step deposition to 1542 s for 6-step deposition, reducing the occupation time of the electrodeposition equipment. As the number of deposition layers increases, the specific capacitance of NiCo-LDH shows a trend of first increasing and then stabilizing. The high mass specific capacitance of NiCo-LDH electrode material deposited in 6 steps is 953 F g−1 at a current density of 3 mA cm−2. The assembled asymmetric supercapacitor device achieved an energy density of 0.309 mWh cm−2 at a power density of 4.25 mW cm−2, and a capacitance retention rate of 94% after 10,000 cycles at a current density of 40 mA cm−2. This indicates that the NiCo-LDH material prepared by multi-step electrodeposition method has good capacitance performance, providing a simple and time-saving method for manufacturing large-scale multi-step electrodeposition of adhesive-free supercapacitor electrodes.

Photoelectrochemical performance of a ternary WO3/BiVO4/NiCo LDH photoanode for high-efficiency water oxidation

Recently, tungsten oxide (WO3) and bismuth vanadate (BiVO4) have been considered as an intriguing combination for constructing a heterojunction for efficient photoelectrochemical (PEC) applications. Herein, we report the preparation of ternary WO3/BiVO4/NiCo layered double hydroxide (LDH) photoanodes for boosting photogenerated carrier transport and promotion of catalytic activity. WO3/BiVO4 heterostructures were synthesized by a hydrothermal process of WO3 nanoplates on a fluorine-doped tin oxide (FTO) glass substrate, followed by spin-coating for BiVO4 materials. We investigated the effect of a NiCo LDH catalyst on PEC performance by controlling the growth temperatures of the NiCo LDH via hydrothermal synthesis. Moreover, the X-ray diffraction (XRD), Fourier‒transform infrared (FTIR) and X‒ray photoelectron spectroscopy (XPS) analyses revealed that the WO3/BiVO4 heterojunction was retained after the NiCo LDH growth process regardless of synthesis temperatures. The PEC results verified that the WO3/BiVO4 heterostructure with the optimized NiCo LDH catalyst (WBN60) possessed the best photocurrent density of 3.2 mA/cm2 at 1.23 V vs. reversible hydrogen electrode (RHE), which created improved charge separation and surface oxidation kinetics of photogenerated carriers. Consequentially, the smallest charge transfer resistance and recombination rate were achieved in the WBN60 electrode compared to others, indicating a much lower photoelectrode‒electrolyte interfacial resistance and the enhancement of photogenerated carrier transport by suppressing recombination.

Ultrafast Microwave-Assisted Synthesis of Porous NiCo Layered Double Hydroxide Nanospheres for High-Performance Supercapacitors.

Currently, new clean energy storage technology must be effective, affordable, and ecologically friendly so as to meet the diverse and sustainable needs of the energy supply. In this work, NiCo-LDH containing intercalated EG was successfully prepared within 210 s using an ultrafast microwave radiation technique. Subsequently, a series of characterization and systematic electrochemical tests were conducted to analyze the composition, structure, and energy storage mechanism of the NiCo-LDH material. The Ni:Co ratio of 5:5 results in the highest capacitance value of 2156 F/g at 1 A/g and an outstanding rate performance of 86.8% capacity retention rate at 10 A/g. The results demonstrated that the unique porous structure of NiCo-LDH and large layer spacing were conducive to more electrochemical reactions. Additionally, an electrochemical test was carried out on the NiCo-LDH as a hybrid supercapacitor electrode material, with NiCo-LDH-5:5 serving as the positive electrode and activated carbon as the negative electrode, the asymmetric supercapacitor can achieve a maximum energy density of 82.5 Wh kg-1 and power density of 8000 W kg-1. The NiCo-LDH-5:5//AC hybrid supercapacitors own 81.5% cycle stability and 100% coulombic efficiency after 6000 cycles at 10 A/g.

Efficient photocatalytic hydrogen production of Ni-Co layered double hydroxides (Ni-Co LDHs) anchored with reduced graphene oxide (rGO) hybrid composite

Using a suitable co-catalyst to boost photocatalytic H2 evolution from water splitting is crucial. Herein, we designed pristine NiCo-LDH and reduced graphene-oxide supported nickel-cobalt layered double hydroxide nanosheets (NiCo-LDH/rGO) as photocatalyst for the first time to evaluate the hydrogen production performance. Adding graphene has the potential to significantly increase electrical conductivity, and the supported NiCo-LDH has the potential to significantly reduce the likelihood of graphene self-aggregation. The effectiveness of its photocatalytic hydrogen generation was analyzed using a set of characterizations. The H2 evolution rates for pure rGO were 345.2 μmolh−1g−1, whereas those for Ni-Co LDH/rGO were 578.2 μmolh−1g−1. Average hydrogen generation per hour for the Ni-Co LDH/rGO composite material was 2032.1 μmolh−1g−1, which was 5.8 and 3.5 times that of rGO and Ni-Co LDH/rGO, respectively, NiCo-LDH@rGO's synergistic impact on the NiCo-LDH boosts the H2 generation pathway by increasing the catalyst's stability as well as performance by exposing active sites and speeding up electron transport. The produced nanocomposite shows excellent spatial charge separation and quicker electron transport across the conductive network of rGO, as shown by the photocurrent response test and photoluminescence (PL) spectra. The results of this study provide a fresh perspective on the practical use and synthesis of the inexpensive and effective NiCo-LDH/rGO, demonstrating the standard deviation of logical planning and preparation of high-performance photocatalysts.

Transparent supercapacitors with networked MXene on NiCo-layered double hydroxide

This study investigates the growth mechanisms of NiCo-layered double hydroxide (LDH) electrodeposition on indium tin oxide (ITO) substrates, aiming to optimize thickness control for transparent supercapacitor applications. Despite the promising energy storage capabilities of NiCo-LDH, long-term cycle stability and transparency degradation due to irreversible redox reactions limit its applicability. To address these challenges, we introduced networked MXene nanosheets into the NiCo-LDH matrix, significantly enhancing electrochemical properties and cycle resilience while maintaining excellent transparency. Under optimized conditions, NiCo-LDH and MXene composites achieved an impressive areal capacitance of 136.9F cm−2 and retained 74.2 % capacitance even after 7000 charge–discharge cycles. Notably, the transparency of the composite remained strong at 80.1 %, outperforming NiCo-LDH without the networked MXene, which retained only 51.4 % transparency after the same cycles, thus indicating that the well-networked MXene nanosheets played a crucial role in improving electrical conductivity and charge-transfer efficiency across the electrode surface. The transparent symmetric supercapacitor developed, utilizing MXene-coated NiCo-LDH, demonstrated outstanding performance with an energy density of 2.23 µWh cm−2 at a power density of 120.00 µW cm−2. Moreover, it showcased an admirable capacitance retention of 85.9 % following 9000 charge–discharge cycles, underlining the robustness of the composites and efficiency for transparent supercapacitor applications. In conclusion, this research highlights the potential of NiCo-LDH/MXene composites for transparent supercapacitors. By carefully controlling thickness and optimizing MXene concentration, we effectively addressed durability and transparency challenges during extended charge–discharge cycles.

Layered double Hydroxides-MXene heterointerfaces with abundant anion vacancies expediting sulfur redox kinetics for High‑Performance Lithium–Sulfur batteries

Lithium-sulfur batteries (LSBs) are increasingly seen as advanced battery systems of great promise, owing to their exceptional energy density and cost-effectiveness. Yet, designing efficient electrocatalysts that can both effectively mitigate the diffusion of soluble lithium polysulfides (LiPSs) and enhance redox kinetics still remains a significant challenge, particularly at high sulfur loadings and lean electrolyte conditions. In this work, we develop NiCo-layered double hydroxides (NiCo-LDHs) nanosheets featuring abundant oxygen vacancies (Vo), anchored on Ti3C2-MXene nanosheets (denoted as Vo-LDHs-MXenes), tailored specifically for high-performance LSBs. The heterointerfaces between MXenes and Vo-LDHs modify the electronic structure and enhance the catalytic activity of the LDHs and MXenes, yielding multifunctional synergistic effects. Our theoretical and electrochemical analyses indicate that the Vo-LDHs-MXenes heterostructures exhibit enhanced affinity for LiPSs and superior catalytic performances compared to individual LDHs. This improvement facilitates the efficient adsorption and conversion of LiPSs, as well as the nucleation and decomposition of Li2S. Consequently, the cell with the Vo-LDHs-MXenes modified separator delivers stable cycling performances with a high initial specific capacity of 938.9 mAh/g over 300cycles at 1.0C and good rate capabilities. Notably, it still achieves a high initial areal capacity of 6.09 mAh cm−2 under a high sulfur loading of 6.7 mg cm−2 and low electrolyte/sulfur (E/S) ratio of 6.0 μL mg−1 over 50cycles.

Sonochemical synthesis of CoNi layered double hydroxide as a cathode material for assembling high performance hybrid supercapacitor

Fabricating battery-type electrode materials with large specific surface area and mesopores is an efficient method for enhancing the electrochemical performance of supercapacitors. This method may provide more active sites for Faradic reactions and shorten the ion-diffusion paths. In this study, the CoNi layered double hydroxides (LDHs) with the morphology of nanoflowers and nanoflakes were prepared in solutions with pH values of 7.5 (CoNi LDH-7.5) and 8.5 (CoNi LDH-8.5) via a simple sonochemical approach. These CoNi LDHs possessed large specific surface areas and favourable electrochemical properties. The CoNi LDH-7.5 delivered a specific capacity of 740.8C/g at a current density of 1 A/g, surpassing CoNi LDH-8.5 with 668.1C/g. The hybrid supercapacitor (HSC) was assembled with activated carbon as the anode and CoNi LDH as the cathode to assess its practical application potential in the field of electrochemical energy storage. The CoNi LDH-7.5//AC HSC achieved the highest energy density of 35.6 W h kg−1 at a power density of 781.1 W kg−1. In addition, both HSCs exhibited little capacity decay over 5,000 cycles at a high current load of 8 A/g. These electrochemical properties of CoNi LDHs make them promising candidates for battery-type electrode materials. The current sonochemical method is simple and can be applied to the preparation of other LDHs-based electrode materials with favourable electrochemical performance.

One-step electrodeposited nickel-cobalt-layered double hydroxide nanosheets with anion intercalation for supercapacitor

NiCo-layered double hydroxide (LDH) is a frequently used materials for electrodes in supercapacitors to achieve high conductivity, large capacity, tunable layered structure and cheap. But its poor rate capability and the lack of active sites requires improvement to release maximum performance. Herein, an electrodeposition method is employed to grow NiCo-LDHs with a series of intercalated anions on carbon paper. It is investigated that the insertion of anions between the layers of LDH augments the quantity of available active sites. These locations enable the diffusion phenomenon and enhance specific capacity. As the current density is set at 1 A·g−1, NiCo-LDH intercalated with PO43− reaches a maximum specific capacity of 287.5 mAh·g−1 (2070 F·g−1). Moreover, the asymmetrical supercapacitor was put together with this material as cathode has a substantial energy density of 49.2 Wh·kg−1 at 375 W·kg−1, exceptional cycle stability with a 92.0 % capacity retention and 99.5 % coulombic efficiency retention after 10,000 cycles. This study offers fresh perspectives on the compositional and structural design of LDH materials for effective and good cyclic stable supercapacitors. In present research, a novel perspective on the composition and structural design of LDH-based electrode materials was provided for outstanding supercapacitors.

Hollow nanocages heterostructured NiCo-LDH/MWCNTs electrocatalyst for highly sensitive and non-invasive detection of saliva glucose

Monitoring salivary glucose has gained increased attention as a non-invasive approach to prevent and diagnose diabetes. Since the glucose concentration in saliva is lower than that in blood, the development of effective electrocatalysts for highly sensitive glucose detection is thus of great significance. In this study, a hollow nanocage from NiCo-layered double hydroxides (LDH) modified with multi-walled carbon nanotubes (MWCNTs) is designed and further employed as the sensing material to construct a novel non-enzymatic glucose electrochemical sensor with high sensitivity. It is synthesized by utilizing pre-synthesized zeolitic imidazolate framework (ZIF-67)/MWCNTs as a sacrificial template and subsequently conducting a simple solvent-thermal reaction with Ni(NO3)2. Such a hollow nanocage preserves the polyhedral framework structure of the used precursor, where the hollow frame-like structure of NiCo-LDH offers accessible catalytic sites, and MWCNTs provides good conductivity. Their combination brings in a bridging effect between MWCNTs and NiCo-LDH, further leading to a large electrochemical active area and excellent catalytic activity of this hollow nanocage. The constructed sensor exhibits a detection limit as low as 0.03 μM for the glucose detection as well as wide linear ranges of 0.1–3000 μM and 3000–9231.8 μM, corresponding to the sensitivity of 2.55 and 1.15 μA mM−1 cm−2, respectively. Moreover, this sensor enables the tracking of glucose concentration change in salivary before and after food intake. This work offers new highly sensitive sensing materials and potentially valuable approaches for non-invasive glucose detection.

Ni foam-supported Cu0.33Co0.67Se2 and modified NiCo-layered double hydroxide nanoarray composites for high-energy-density hybrid supercapacitors

High-performance supercapacitors, valued for their extended operational lifespan and remarkable power density, have garnered significant attention as potential energy storage solutions. Nevertheless, their practical application has been impeded by the limited energy density and unsatisfied rate capability of conventional electrode materials. To address these challenges, we developed an effective approach for crafting a composite material, featuring a core-shell nanostructure comprised of dodecyl sulfate (DS) ions intercalated Cu0.33Co0.67Se2/NiCo-DS-LDH nanostructures. The synergistic inter-component effect between copious active sites of Cu–Co–Se and DS-modified NiCo-LDH readily boosts the high specific capacity as ∼488 mAh g−1 at 1 A g−1 with an enhanced capacity retention of ∼36.3%. In this material system, the Cu0.33Co0.67Se2/NiCo-DS-LDH cathode-integrated hybrid supercapacitor device, with the N, S co-doped porous carbon anode achieves an energy density of ∼54.4 Wh kg−1 at a power density of ∼801 W kg−1. These exceptional electrochemical performances can be attributed to the combinatorial effect of the high conductivity of the Ni network, the high activity of the bimetallic selenide, and the expanded interlayer spacing of the NiCo-LDH. The current work presents a newly developed strategy for the design of promising transition metal-based composites with a rational architecture, offering significant potential for next-generation energy storage systems.

Heterogeneous Fe doped NiCo-layered double hydroxides grown on nickel foam induce spin exchange interactions for magnetization and high-performance supercapacitor applications

Supercapacitors have attained many attentions since their unique features of high power density and excellent cycle life. However, the great challenge for practical applications is that the energy density is much lower than fuel batteries. Herein, we develop a simple strategy to rationally design nanostructured FeNiCo-Layered Double Hydroxides (LDHs) self-assembled on 3D nickel foam (NF) by using a hydrothermal technique and their supercapacitors behaviors are studied in this works. Benefiting from the synergistic modulation of redox-active sites, Faradaic redox reaction and spin exchange interactions, FeNiCo-LDHs/NF displays ferromagnetism at room temperature and shows advanced supercapacitor property with a high specific capacity of 2284.7 F g−1 at 2 A g−1. Furthermore, an asymmetric supercapacitor (ASC) is assembled using FeNiCo-LDHs/NF as the anode and active carbon (AC) as the cathode, exhibiting excellent supercapacitor property. A considerable energy density is up to 133.7 W h kg−1 at a power density of 3.2 kW kg−1 and the capacitance is retained at 97.9% even after 5000 cycles. The results can provide an efficient fabrication for further advancing the energy density of bimetallic LDHs in energy storage applications.

Electronic Modulation in Cu Doped NiCo LDH/NiCo Heterostructure for Highly Efficient Overall Water Splitting.

Layered double hydroxides (LDHs), promising bifunctional electrocatalysts for overall water splitting, are hindered by their poor conductivity and sluggish electrochemical reaction kinetics. Herein, a hierarchical Cu-doped NiCo LDH/NiCo alloy heterostructure with rich oxygen vacancies by electronic modulation is tactfully designed. It extraordinarily effectively drives both the oxygen evolution reaction (151mV@10mAcm-2) and the hydrogen evolution reaction (73mV@10mAcm-2) in an alkaline medium. As bifunctional electrodes for overall water splitting, a low cell voltage of 1.51V at 10mAcm-2 and remarkable long-term stability for 100h are achieved. The experimental and theoretical results reveal that Cu doping and NiCo alloy recombination can improve the conductivity and reaction kinetics of NiCo LDH with surface charge redistribution and reduced Gibbs free energy barriers. This work provides a new inspiration for further design and construction of nonprecious metal-based bifunctional electrocatalysts based on electronic structure modulation strategies.

Fabrication of a novel superaerophobic support structure for NiCo-layered double hydroxide electrocatalysts for the oxygen evolution reaction

In this work, 3D Ni substrate with superaerophobic properties were catalyzed through the deposition of NiCo layered double hydroxide (NiCo-LDH). Deposition of NiCo-LDH was achieved using a mixed solution of Ni and Co nitrate salts as precursors. Precipitation of NiCo-LDH was achieved by the application of a negative current that caused a local raise of the solution pH. NiCo-LDHs were deposited in the form of vertically aligned nanosheets that infiltrate throughout the porous structure of the superaerophobic 3D Ni substrate. Variation of the deposition current changed the composition of the NiCo-LDH. The performance and the mechanisms responsible for the OER were investigated through a series of electrochemical experiments that include electrochemical impedance spectroscopy. As exemplified by a change of the Tafel slope from ca. 60 to 40 mV/decade, the OER mechanism is modified by the deposition the NiCo-LDH. In 1 M KOH at room temperature, the best electrode has overpotential as small as 269 and 340 mV at 10 and 250 mA cm−2, respectively. Longer-term electrolysis test during 56 h at 250 mA cm−2 showed a constant overpotential of 340 mV, without any sign of degradation.

Constructing Hierarchical CoGa2O4-S@NiCo-LDH Core-Shell Heterostructures with Crystalline/Amorphous/Crystalline Heterointerfaces for Flexible Asymmetric Supercapacitors.

The rational design and construction of composite electrodes are crucial for overcoming the issues of poor working stability and slow ionic electron mobility of a single component. Nevertheless, it is a big challenge to construct core-shell heterostructures with crystalline/amorphous/crystalline heterointerfaces in straightforward and efficient methods. Here, we have successfully converted a portion of crystalline CoGa2O4 into the amorphous phase by employing a facile sulfidation process (denoted as CoGa2O4-S), followed by anchoring crystalline NiCo-layered double hydroxide (denoted as NiCo-LDH) nanoarrays onto hexagonal plates and nucleation points of CoGa2O4-S, synthesizing dual-type hexagonal and flower-like 3D CoGa2O4-S@NiCo-LDH core-shell heterostructures with crystalline/amorphous/crystalline heterointerfaces on carbon cloth. Furthermore, we further adjust the Ni/Co ratio in LDH, achieving precise and controllable core-shell heterostructures. Benefiting from the abundant crystalline/amorphous/crystalline heterointerfaces and synergistic effect among various components, the CoGa2O4-S@Ni2Co1-LDH electrode exhibits a specific capacity of 247.8 mAh·g-1 at 1 A·g-1 and good rate performance. A CoGa2O4-S@Ni2Co1-LDH//AC flexible asymmetric supercapacitor provides an energy density of 58.2 Wh·kg-1 at a power density of 850 W·kg-1 and exhibits an impressive capacitance retention of 105.7% after 10,000 cycles at 10 A·g-1. Our research provides profound insights into the design of other similar core-shell heterostructures.

Improving the composite-structured supercapacitor assembled with Ni–Co-layered double hydroxide and polymer cement electrolyte through structural optimization

The optimized nickel–cobalt double hydroxide electrode by electrodeposition has a high specific area capacitance of 10.53 F cm−2. Capacitors assembled using the optimized electrodes have a specific capacitance of up to 1.442 F cm−2.

The Interwoven Structured Two‐Dimensional NiCo Layered Double Hydroxide Tortuous Nanosheet as Performance‐Enhanced Electrode Material toward Battery‐Type Supercapacitor

The Interwoven Structured Two‐Dimensional NiCo Layered Double Hydroxide Tortuous Nanosheet as Performance‐Enhanced Electrode Material toward Battery‐Type Supercapacitor

Alternately electrodeposited mesoporous NiCoSe2@MnO2 nanocomposite-anchored Ni-Co layered double hydroxide nanoneedles for hybrid supercapacitors

A rational strategy for preparing effective electrode materials is crucial for high-performance electrochemical energy storage devices. Herein, a facile route is developed to construct hierarchical composite electrodes (NiCoLDH@NiCoSe2@MnO2) consisting of...

A surface defect strategy of NiCo-layered double hydroxide decorated MXene layers for durable solid-state supercapacitors

The aggregation and self-stacking of MXenes and layered double hydroxides (LDHs) in the electrode preparation process are considered the primary obstacles to their practical applications.

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.