NiCo-layered Double Hydroxide Research Articles

Template-directed strategy synthesis of CoNi-layered double hydroxide nanosheet coated with polypyrrole for enhanced capacitive deionization

Recently, faradic material layered double hydroxide (LDH) has been widely used as an anode for capacitive desalination (CDI), due to its reversible ion insertion/deintercalation process and high anion storage capacity. Unfortunately, the issues of poor conductivity and self-stacking of LDH limit its application in the CDI. Herein, CoNi-LDH coated with polypyrrole (PPy@CoNi-LDH) was meticulously designed and synthesized using ZIF-67 as the precursor by template-directed strategy and in-situ polymerization. The CoNi-LDH has large interlayer distance of 0.91 nm, which is beneficial for ion insertion. Introduced PPy conductive layer improved the interface transfer rate of charges and increased the ion storage capacity of composite. The experimental test results indicate that PPy@CoNi-LDH1:1 electrode has a higher specific capacitance of 223.1 F g−1 and lower resistivity of 62.33 Ω·cm compared to CoNi-LDH electrode (35.2 F g−1 and 3.39 × 104 Ω·cm). Obtained PPy@CoNi-LDH1:1 also has abundant mesoporous and excellent hydrophilicity, which can promote ions transfer. Meanwhile, the specific surface area of PPy@CoNi-LDH1:1 with the coating structure is 1.78 times that of CoNi-LDH, effectively suppressing the self-stacking of CoNi-LDH and exposing more active sites. When employed PPy@CoNi-LDH1:1 as an anode and the activated carbon as a cathode, the PPy@CoNi-LDH1:1//AC cell exhibited a high Cl− removal capacity (60.20 mg g−1), a swift Cl− removal rate (11.45 mg g−1 min−1) and good cycling stability (the retention rate is 89.67 % after 50 cycles) in NaCl solution of 500 mg L−1 and 1.4 V applied voltage. Additionally, the adsorption mechanism indicated that surface charge attraction, ligand exchange, and ion insertion jointly promote the Cl− removal. This study provides a feasible solution about successful design of high adsorption capacity anode materials for CDI.

Ce-doped NiCo-layered double hydroxide based self-supporting tremella-shaped nanoflower heterostructure as efficient electrocatalyst for the oxygen evolution reaction

NiCo-layered double hydroxide (NiCo-LDH) catalysts, which indicate a profound prospect of oxygen evolution reaction (OER) under alkaline conditions, are facing great challenges in terms of low electrical conductivity, restricted by poor conductivity, limited electrochemical reaction sites, and low-density of edge sites. The authors developed a simple and convenient in-situ one-pot self-assembly method. The Ce-doped defective NiCo-LDH hexagonal nanosheets and nitrogen-doped graphene fabricated the NiCoCe-LDH/RNF electrocatalyst on the nickel foam (NF) substrate, which demonstrated excellent OER activity under alkaline conditions, only needed 299 mV overvoltage to achieve 50 mA cm−2 current intensity, could last for 6 hours at 20 mA cm−2. The highly active OER benefited from the structural advantages of the novelty three-dimensional array structure. The novel geometric structure of tremella-shaped nanoflower integrated with curved nanosheets and curled edges loaded on NF provides more electrochemical reaction sites for intermediate coordination. The nitrogen-doped reduced graphene oxide accommodated better interaction between active materials and charge carriers, enhancing the conductivity and electron transfer performance of nanostructures. The effective synergistic between the heterostructures promoted the excellent OER electrocatalytic activity of NiFeCe-LDH/RNF nanocomposites. DFT calculations at the atomic level of pristine and Ce-doped NiCo-LDH exhibited that Ce-doping can reduce the Gibbs free energy of the potential-determining step and improve the catalytic activity of OER. This work has broadened the horizons for developing simple and highly available OER electrocatalysts.

CoNi-layered double hydroxide derived CoS2/NiS2 dodecahedron decorated with ReS2 Z-scheme heterojunction for efficient hydrogen evolution

The high efficient utilization of light absorption and the effective separation of photogenerated carriers are critical factors in enhancing the performance of photocatalysts. In this study, CoNi-layered double hydroxide was synthesized using zeolitic imidazolate frameworks-67 as a template, followed by calcination to form CoS2/NiS2. Subsequently, ReS2 was deposited onto the surface of CoS2/NiS2, resulting in the ReS2/CoS2/NiS2 photocatalyst demonstrated notable hydrogen evolution activity under visible light, achieving a maximum hydrogen production rate of 40111.8 μmol/g. The construction of the Z-scheme heterojunction was found to facilitate the transfer and separation of photogenerated carriers while extending the lifetime of photogenerated electrons, thereby contributing to the enhancement of photocatalytic activity. This study provides a new approach for the development of sulfide heterojunctions aimed at improving photocatalytic hydrogen production efficiency.

A mild, configurable, flexible CoNi-LDH(v)/Zn battery based on H-vacancy-induced reversible Zn2+ intercalation

Flexible Zn-based batteries have attracted increasing research interest as essential components of wearable energy storage devices. However, the advancement of flexible aqueous Zn-based batteries based on Co-Ni layered double hydroxide (CoNi-LDH) as the cathode material is hampered by their poor cycling stability and the corrosiveness of alkaline electrolytes. Herein, CoNi-LDH nanosheets enriched with H vacancies (CoNi-LDH(v)) were constructed on a flexible carbon cloth (CC) substrate via electrochemical deposition and activation. The Zn-based battery comprising CoNi-LDH(v)@CC as the cathode exhibited highly reversible conversion reactions and stable operation in 3 M ZnSO4 electrolyte (pH = 4). The battery delivered an excellent specific capacity (225 mA h g−1, 0.26 mA h cm−2), acceptable cycling stability (53.9%, 900 cycles), and high discharging voltage. The abundant H vacancies served as active sites for the reversible intercalation of Zn2+ and the extravasation of NO3− generated channels and space for Zn2+ transport and storage, together enabling an excellent Zn2+ storage capacity. Furthermore, a sandwich-structured solid-state CoNi-LDH(v)@CC//Zn@CC battery was fabricated and was found to exhibit a noteworthy electrochemical performance and mechanical durability. As a proof of concept, the unencapsulated battery powered a digital watch under various deformation conditions and operated stably for 80 h. Additionally, the flexible battery displayed outstanding customizability, maintaining an open-circuit voltage of 1.42 V even after being cut twice. The proposed engineering strategy contributes to the realization of textiles with truly wearable energy-storage devices.

MXene Supported Electrodeposition Engineering of Layer Double Hydroxide for Alkaline Zinc Batteries

AbstractThe main challenges faced by aqueous rechargeable nickel‐zinc batteries are their comparatively low energy density and poor cycling stability, mainly due to the limited capacity and reversibility of existing Ni‐based cathodes. Moreover, the preparation procedures of these cathodes are complex and not easily scalable, which makes them less promising for large‐scale energy storage. Herein, we utilized MXene as a functional additive to effectively improve the electrodeposition preparation of NiCo layered double hydroxides (LDH). Benefiting from the improved interfacial contact between nickel foam (NF) and platting solution and the enhanced ionic conductivity of platting product based on MXene additives, the resulting binder‐free NiCo LDH electrode can achieve ultrahigh areal loading (~65 mg cm−2) with abundant active surface for redox reactions and maintained short transport pathway for ion diffusion and charge transfer. Furthermore, the as‐fabricated alkaline NiCo LDH‐based battery delivers high discharge capacity, up to 20.2 mAh cm−2 (311 mAh g−1), accompanied by remarkable rate performance (9.6 mAh cm−2 or 148 mAh g−1 at 120 mA cm−2). Due to the high structural and chemical stability of MXenes/LDH‐based electrode, excellent cycling life can also be achieved with 88.6 % capacity retention after 10000 cycles. In addition, ultrahigh areal energy density (31.2 mWh cm−2) and gravimetric energy density (465 Wh kg−1) can be simultaneously achieved. This work has inspired the design of advanced cathode materials to develop high‐performance aqueous zinc batteries.

An electrochemical sensor based on porous heterojunction hollow NiCo-LDH/Ti3C2Tx MXenes composites for the detection of quercetin in natural plants.

Cubic hollow-structured NiCo-LDH was synthesized using a solvothermal method. Subsequently, clay-like Ti3C2Tx MXenes were electrostatically self-assembled with NiCo layered double hydroxides (NiCo-LDH) to form composites featuring three-dimensional porous heterostructures. The composites were characterized using SEM, TEM, XRD, XPS, and FT-IR spectroscopy. Ti3C2Tx MXenes exhibit excellent electrical conductivity and hydrophilicity, providing abundant binding sites for NiCo-LDH, thereby promoting an increase in ion diffusion channels. The formation of three-dimensional porous heterostructural composites enhances charge transport, significantly improving sensor sensitivity and response speed. Consequently, the sensor demonstrates excellent electrochemical detection capabilityfor quercetin (Qu), with a detection range of 0.1-20 µM and a detection limit of 23 nM. Additionally, it has been applied to the detection of Qu in natural plants such as onion, golden cypress, and chrysanthemum. The recovery ranged from 97.6 to 102.28%.

Lattice Strain-Induced D-Band Modulation in Nanosheets of CuxNiCo-Layered Double Hydroxides for Enhanced Water Electrolysis

Lattice Strain-Induced D-Band Modulation in Nanosheets of Cu_<i>x</i>NiCo-Layered Double Hydroxides for Enhanced Water Electrolysis

N/O-bridge stimulated robust binding energy and fast charge transfer between carbon nanofiber and NiCo LDH for advanced supercapacitors

Layered double hydroxide (LDH)-carbon composites effectively mitigate the inherent issues of agglomeration and poor conductivity in LDH. However, the weak binding energy and insufficient charge transfer capability between LDH and carbon substrate significantly compromise the active substance loading, cyclic stability and practical capacity of the composites. Herein, N/O co-doping porous carbon nanofibers (NOPCNFs) are first prepared by blending diminutive zinc imidazolate framework-8 nanoparticles with polyacrylonitrile for electrospinning, and then densely packed NiCo LDH nanosheets are homogeneously anchored on NOPCNFs to form NiCo LDH@NOPCNFs heterostructure via a hydrothermal method. The experimental findings and density functional theory calculation results indicate that N/O atoms exhibit robust binding forces with metal atoms through enhanced electrostatic adsorption and p-d covalent hybridization, which facilitates the nucleation and development of NiCo LDH on carbon nanofibers. Meanwhile, these heteroatoms also serve as the bridge for electron transfer from NiCo LDH to NOPCNF, leading to a strong interfacial electric field, thus accelerating charge transfer behaviors. Benefitting from the synergistic interaction between NiCo LDH and NOPCNF, the obtained NiCo LDH@NOPCNFs demonstrate an elevated mass loading of active substance (55 wt%), an impressive specific capacitance of 1340 F/g at 1 A/g (based on the mass of NiCo LDH, 2463 F/g), and good cyclic durability for 5000 cycles. Moreover, an all-solid-state asymmetric supercapacitor using NOPCNFs and NiCo LDH@NOPCNFs shows promising practical application prospects. This work gives insights into the important influence of heteroatom doping in carbon, and provides a feasible approach for the efficient integration of electroactive and carbon material.

Influence of metal ion doping for the electrochemical performance of NiCo layered double hydroxide nanostructures

Layered double hydroxide (LDH) is considered to be a potential energy storage material due to its high theoretical specific capacitance and microstructure. However, poor conductivity restricts their application and development in energy storage devices. Considering metal cations doping as an effective way to improve conductivity of semiconductors, metal cations doping can also be used to improve the conductivity of LDH. In the study, metal ions with different valence states are selected and doped into the NiCo LDH nanostructures. Indeed, metal cations doping can improve the conductivity of NiCo LDH, which can be confirmed by the results of EIS analysis. But the corresponding changes in electrode capacity are different. Compared with the Ag+ and Zn2+, Al3+ ion doped in NiCo LDH can achieve significant improvement of capacity. The capacity can reach 2130 F/g at a current density of 2 A/g when the doping concentration of Al3+ is 0.02, which has 48 % improvement compared to the original NiCo LDH (1435 F/g). The improvement of conductivity dose not determine the increase of capacity, the type and valence states of elements are also key factors affecting material capacity. Therefore, this study provides an idea for the subsequent doping of metal cations in LDH materials.

Fabrication of Platinum-Decorated NiCo-Layered Double Hydroxide Nanoflowers for Electrocatalytic Ammonia Oxidation Reaction

The complete anodic oxidation of ammonia is an important part of direct ammonia fuel cells. Fabricating a high-performance electrocatalyst for ammonia oxidation reaction is meaningful for developing a direct ammonia fuel cell. Herein, we designed one platinum-decorated NiCo-layered double hydroxide nanoflower on Ni foam (Pt-NiCo-LDH-Ni foam) and measured the electrocatalytic performance via the cyclic voltammetry (CV) technique. The experimental results demonstrated that the optimized Pt-NiCo-LDH-Ni foam showed great electrocatalytic performance, with a low overpotential with a value of −0.573 V, a high current density of 17.75 mA cm−2 for the ammonia oxidation reaction, and good stability.

A Systematic Study of NiCo Layered Double Hydroxides Grown on Porous Carbon for Hybrid Battery-like Supercapacitor Electrodes: Growth Method, Morphology, and Composition

A Systematic Study of NiCo Layered Double Hydroxides Grown on Porous Carbon for Hybrid Battery-like Supercapacitor Electrodes: Growth Method, Morphology, and Composition

NiCo layered double hydroxides/carbon dots composites with S-doing for high-performance asymmetric supercapacitors

The pursuit of high-performance electrode materials for supercapacitors has led to the exploration of transition metal layered double hydroxides (LDH), which boast an impressive theoretical specific capacitance. However, their intrinsic limitations, such as poor electronic conductivity and slow diffusion kinetics, have posed significant challenges for their practical implementation. In this work, a NiCo LDH/carbon dots (CDs) composite with S-doping has been meticulously designed to overcome the aforementioned limitations through a synergistic combination of heteroatom doping and carbon incorporation. Utilizing a one-pot hydrothermal method, the composite electrode for the application of asymmetric supercapacitors have been in-situ growth on Ni foam substrate, which not only serves as a robust support but also contributes to the formation of NiCo LDH by providing a uniform Ni source, thereby ensuring strong adhesion and structural integrity. The morphology and microstructures of composites could be finely modulated by adjusting CDs amount. With moderate CDs contents, the optimum electrode S-LDH/CDs-2 exhibits distinctive 3D needle-like spherical morphology, coupled with the ample space for ion diffusion. Consequently, the electrode demonstrates outstanding electrochemical performance, featuring a high areal capacitance of 5157 mF cm−2 at a current density of 2 mA cm−2. Additionally, it exhibits noteworthy rate performance and maintains excellent cycling stability. Integrating the innovative electrode into asymmetric supercapacitors configuration, superior energy density (0.24–0.45 mWh cm−2) and power density (4–20 mW cm−2) as well as good stability have been achieved for the S-LDH/CDs-2//AC device. These results indicate that S-doped NiCo LDH/CDs composite electrode has the desirable potential to be a candidate for energy storage devices.

Ag/Nico LDH Heterogeneous Structure for Efficient Alkaline Oxygen Evolution

Hydrogen is regarded as an ideal energy carrier owing to the highest energy density, presenting the possibility of substituting for traditional fossil fuels. Nowadays, water splitting is significant in producing large-scale hydrogen. However, the sluggish reaction kinetics during anodic OER, caused by the four-electron transfer, has hindered this energy conversion strategy. Although IrO2 and RuO2 are currently the representative OER electrocatalysts, their high cost and unsatisfactory performance limit their commercial application.Numerous electrocatalysts, including oxides, hydroxides, high-entropy alloy, metal organic frameworks, and their hybrids, have been developed to address this issue. Among them, layered double hydroxides (LDH) have demonstrated outstanding performance due to their highly adjustable structure, powerful host-guest interaction, and single-atomic-like active sites. NiCo LDH has attracted significant attention because of its appropriate atomic and electronic structure, intrinsic active sites and defects, compared with single-type Ni-based or Co-based catalysts. However, to meet the requirements of industrial production, a simple and scalable method to synthesize electrocatalysts with favorable OER activity and stability is imperative.We propose a facile and scalable strategy to synthesize Ag-decorated NiCo LDH (Ag/NiCo LDH) by electrodeposition and subsequent spontaneous redox reaction. A spontaneous redox reaction driven by the difference in standard redox potential of reactants can be applied to prepare heterogeneous catalysts in consequence of the facile process, tight combination between substrate and decorated materials, and no supplementary energy input. Silver metal, with its appropriate standard redox potential, good conductivity, and low cost compared to Iridium and Ruthenium, serves as a suitable decorated material. This strategy provides several advantages, for example, Ⅰ) optimizing the electronic structure of Ni and Co by the charge transfer from Ni, Co to Ag; Ⅱ) exposing more active surface area because of the heterogeneous structure, Ⅲ) improving the charge transfer capacity owing to the excellent conductivity of Ag nanoparticles, Ⅳ) increasing the stability of NiCo LDH due to the tight combination of Ag and NiCo LDH, Ⅴ) lowering the catalysts' price compared with Iridium and Ruthenium.The synthesized Ag/NiCo LDH exhibits enhanced OER performance in 1M KOH electrolyte, achieving an overpotential of 440 mV at a current density of 1000 mA cm-2 geo, surpassing that of NiCo LDH (722 mV at 1000 mA cm-2 geo). Surprisingly, Ag/NiCo LDH demonstrates exceptional durability, lasting over 425 h at 1000 mA cm-2 geo, an improvement of nearly eight-fold compared to NiCo LDH (50 h). This study provides a promising approach for developing efficient and stable electrocatalysts for alkaline oxygen evolution.

Kinetics of Temperature-Modulated Water Splitting: Enhancing Efficiency for Hydrogen Generation Using Cu-Doped Nico-Layered Double Hydroxides

Ensuring the efficiency of an electrocatalyst under non-ambient conditions especially at high temperature, is crucial for their facile integration in industrial electrolysers. Varying temperatures governs the thermodynamic and kinetics aspects of water electrolysis by altering reactions rates, conductivity, and adsorption-desorption mechanism. This directly impacts the extent of hydrogen/oxygen evolution reactions (HER/OER). This study demonstrates that the Cu-doped trimetallic NiCoLDHs nanocatalysts shows significant improvement in overpotential ~20% and 10% for OER, and HER, respectively, compared to room temperature electrolysis. Further, to evaluate the effect of elevated temperatures on the kinetics of HER/OER, activation energies were calculated. For HER, the activation energy was found to be 14.4 kJ mol-1, while for OER, it was ~23 kJ mol-1. Density functional theory calculations were carried out to determine the electronic and band structure of the electrocatalysts. The results explains the reasons of increase in their electronic conductivity and electrocatalytic activity for HER/OER at elevated temperatures.

Construction of 3D hollow NiCo-layered double hydroxide nanostructures for high-performance industrial overall seawater electrolysis

Construction of 3D hollow NiCo-layered double hydroxide nanostructures for high-performance industrial overall seawater electrolysis

MXene Supported Electrodeposition Engineering of Layer Double Hydroxide for Alkaline Zinc Batteries.

The main challenges faced by aqueous rechargeable nickel-zinc batteries are their comparatively low energy density and poor cycling stability, mainly due to the limited capacity and reversibility of existing Ni-based cathodes. Moreover, the preparation procedures of these cathodes are complex and not easily scalable, which makes them less promising for large-scale energy storage. Herein, we utilized MXene as a functional additive to effectively improve the electrodeposition preparation of NiCo layered double hydroxides (LDH). Benefiting from the improved interfacial contact between nickel foam (NF) and platting solution and the enhanced ionic conductivity of platting product based on MXene additives, the resulting binder-free NiCo LDH electrode can achieve ultrahigh areal loading (~65 mg cm-2) with abundant active surface for redox reactions and maintained short transport pathway for ion diffusion and charge transfer. Furthermore, the as-fabricated alkaline NiCo LDH-based battery delivers high discharge capacity, up to 20.2 mAh cm-2 (311 mAh g-1), accompanied by remarkable rate performance (9.6 mAh cm-2 or 148 mAh g-1 at 120 mA cm-2). Due to the high structural and chemical stability of MXenes/LDH-based electrode, excellent cycling life can also be achieved with 88.6 % capacity retention after 10000 cycles. In addition, ultrahigh areal energy density (31.2 mWh cm-2) and gravimetric energy density (465 Wh kg-1) can be simultaneously achieved. This work has inspired the design of advanced cathode materials to develop high-performance aqueous zinc batteries.

Multifunctional electromagnetic wave absorbing carbon fiber/Ti3C2TX MXene fabric with superior near-infrared laser dependent photothermal antibacterial behaviors

Developing multifunctional materials which could simultaneously possess anti-bacterial ability and electromagnetic (EM) absorption ability during medical care is quite essential since the EM waves radiation and antibiotic-resistant bacteria are threatening people’s health. In this work, the multifunctional carbon fiber/Ti3C2Tx MXene (CM) were synthesized through repeated dip-coating and following in-situ growth method. The as-fabricated CF/MXene displayed outstanding EM wave absorption and highly efficient photothermal converting ability. The minimum reflection loss (RL) of −57.07 dB and ultra-broad absorption of 7.74 GHz could be achieved for CM composites. By growth of CoNi-layered double hydroxides (LDHs) sheets onto MXene, the absorption bandwidth for carbon fiber/Ti3C2Tx MXene layered double hydroxides (CML) could be reach 5.44 GHz, which could cover the whole Ku band. The excellent photothermal effect endow the CM composites with excellent antibacterial performance. The antibacterials tests indicated that nearly 100 % bactericidal efficiency against E. acoil and S. aureus was obtained for the CM composite after exposure to near-infrared region (NIR) irradiation. This work provides a promising candidate to combat medical device-related infections and EM pollution.

Confinement and interface engineering boosting the capacitive performance by constructing NiCo-LDH@CoSe core-shell structure for supercapacitor

The strategic design of heterostructures in multicomponent composites is a promising approach for enhancing the properties of energy storage materials. While NiCo layered double hydroxide (NiCo-LDH) exhibits favorable ion exchange and redox capabilities, its nanostructure suffers from poor conductivity, leading to aggregation during charge and discharge cycles and compromising its electrochemical stability. This study presents the novel synthesis of NiCo-LDH@CoSe core-shell heterostructure using a two-step electrodeposition technique. The NiCo-LDH@CoSe heterojunction has remarkable electrochemical characteristics, boasting a high specific capacitance of 1965.4 F·g−1 at 1 A·g−1. It also exhibits an impressive rate performance of 74.4 % at 20 A·g−1, and retains 83.3 % of its capacitance after enduring 10,000 cycles at 30 A·g−1. The confinement and interface engineering of the heterojunction facilitate enhanced charge transfer from CoSe to NiCo-LDH, leading to exceptional performance and effectively addressing challenges such as poor conductivity, structural degradation, and nanoparticle clustering. The assembled NiCo-LDH@CoSe//AC hybrid supercapacitor also shows excellent performance. This research underscores the effectiveness of core-shell structure confinement and interface engineering in enhancing electrochemical performance.

Interfacial Super‐Assembly of Vacancy Engineered Ultrathin‐Nanosheets Toward Nanochannels for Smart Ion Transport and Salinity Gradient Power Conversion

AbstractIon‐selective nanochannel membranes assembled from two‐dimensional (2D) nanosheets hold immense promise for power conversion using salinity gradient. However, they face challenges stemming from insufficient surface charge density, which impairs both permselectivity and durability. Herein, we present a novel vacancy‐engineered, oxygen‐deficient NiCo layered double hydroxide (NiCoLDH)/cellulose nanofibers‐wrapped carbon nanotubes (VOLDH/CNF‐CNT) composite membrane. This membrane, featuring abundant angstrom‐scale, cation‐selective nanochannels, is designed and fabricated through a synergistic combination of vacancy engineering and interfacial super‐assembly. The composite membrane shows interlayer free‐spacing of ~3.62 Å, which validates the membrane size exclusion selectivity. This strategy, validated by DFT calculations and experimental data, improves hydrophilicity and surface charge density, leading to the strong interaction with K+ ions to benefit the low ion transport resistance and exceptional charge selectivity. When employed in an artificial river water|seawater salinity gradient power generator, it delivers a high‐power density of 5.35 W/m2 with long‐term durability (20,000s), which is almost 400 % higher than that of the pristine NiCoLDH membrane. Furthermore, it displays both pH‐ and temperature‐sensitive ion transport behavior, offering additional opportunities for optimization. This work establishes a basis for high‐performance salinity gradient power conversion and underscores the potential of vacancy engineering and super‐assembly in customizing 2D nanomaterials for diverse advanced nanofluidic energy devices.

Interfacial Super-Assembly of Vacancy Engineered Ultrathin-Nanosheets Toward Nanochannels for Smart Ion Transport and Salinity Gradient Power Conversion.

Ion-selective nanochannel membranes assembled from two-dimensional (2D) nanosheets hold immense promise for power conversion using salinity gradient. However, they face challenges stemming from insufficient surface charge density, which impairs both permselectivity and durability. Herein, we present a novel vacancy-engineered, oxygen-deficient NiCo layered double hydroxide (NiCoLDH)/cellulose nanofibers-wrapped carbon nanotubes (VOLDH/CNF-CNT) composite membrane. This membrane, featuring abundant angstrom-scale, cation-selective nanochannels, is designed and fabricated through a synergistic combination of vacancy engineering and interfacial super-assembly. The composite membrane shows interlayer free-spacing of ~3.62 Å, which validates the membrane size exclusion selectivity. This strategy, validated by DFT calculations and experimental data, improves hydrophilicity and surface charge density, leading to the strong interaction with K+ ions to benefit the low ion transport resistance and exceptional charge selectivity. When employed in an artificial river water|seawater salinity gradient power generator, it delivers a high-power density of 5.35 W/m2 with long-term durability (20,000s), which is almost 400 % higher than that of the pristine NiCoLDH membrane. Furthermore, it displays both pH- and temperature-sensitive ion transport behavior, offering additional opportunities for optimization. This work establishes a basis for high-performance salinity gradient power conversion and underscores the potential of vacancy engineering and super-assembly in customizing 2D nanomaterials for diverse advanced nanofluidic energy devices.