Nickel-cobalt Layered Double Hydroxide Research Articles

Plasma-assisted synthesis of nickel-cobalt nitride–oxide hybrids for high-efficiency electrochemical hydrogen evolution

The rational design of high-performance electrocatalysts based on nonprecious metals is a key for the development of water-splitting technology. In this work, porous nickel-cobalt nitride–oxide (NiCo–N–O) nanosheet hybrids in a networked configuration are synthesized on carbon cloth through in situ plasma treatment of nickel-cobalt layered double hydroxide (LDH) precursors. The self-supported NiCo–N–O electrodes exhibit the outstanding catalytic activity of hydrogen evolution reaction (HER) with a low overpotential of 50 mV at 10 mA cm−2 in alkaline conditions. The synergistic effects of the morphology, microstructure, and electron transfer between nickel-cobalt nitride and oxide and the favorable role of introducing bimetallic Ni and Co sites on the enhanced electrocatalytic activities are discussed. This work provides a simple and feasible pathway to prepare porous bimetal nitride–oxide hybrid HER electrocatalysts with high efficiency and stability.

Synthesis of NiCo-LDH/MXene hybrids with abundant heterojunction surfaces as a lightweight electromagnetic wave absorber

In this research, a flower-like nickel/cobalt layered double hydroxide (NiCo-LDH) was synthesized and mixed with flaky MXene to obtain a series of NiCo-LDH/MXene hybrids. The NiCo-LDH/MXene hybrids with excellent electromagnetic wave (EMW) absorption performance were obtained by adjusting the load of MXene in the mixture. For a NiCo-LDH/MXene hybrid, its excellent EMW performance comes from the synergistic effect of dielectric loss and magnetic loss as well as the excellent attenuation ability and impedance matching characteristics of the material. The results showed that only with a thickness of 2.18 mm at 12.0 GHz, a minimum reflection loss (RLmin) of −64.24 dB was obtained when the MXene content is 75 wt%. For the same sample, a maximum effective absorption bandwidth (EAB, RL <−10 dB) of 4.48 GHz (11.04 ~15.52 GHz) was obtained only with a thickness of 2.00 mm. This research proved the effect of the structure and composition of EMW absorber on its performance, and developed ideas for the design and development of high-performance EMW absorption materials.

Effect of soft template on nickel-cobalt layered double hydroxides grown on nickel foam as battery-type electrodes for hybrid supercapacitors

Nickel-cobalt layered double hydroxides (NiCo-LDHs) are successfully synthesized on nickel foam by the simple hydrothermal process, with polyvinylpyrrolidone (PVP), cetyltrimethyl ammonium bromide (CTAB), polyvinyl alcohol (PVA), and sodium dodecyl sulfate (SDS) as template agents, respectively. The prepared NiCo-LDHs present different morphology and outstanding electrochemical performances. Particularly, the NiCo-LDHs samples with CTAB as template agents (NC-C) exhibit high specific capacity (869.48 C g−1 at 1 A g−1) and excellent durability (88.23% capacity retention after 2000 cycles). Furthermore, the hybrid supercapacitors (HSCs) device based on NC-C and activated carbon electrodes deliver an energy density of 48.34 Wh kg−1 at a power density of 799.84 W kg−1 and satisfactory cycle stability (90.83% capacity retention after 2000 cycles). These properties indicate that the prepared materials could become ideal electrode materials for asymmetric supercapacitors.

Designing nanofibrous membrane with biomimetic caterpillar-like structured for highly-efficient and simultaneous removal of insoluble emulsified oils and soluble dyes towards sewage remediation

Purification of insoluble emulsified oils and soluble organic pollutants from sewage has attracted tremendous attention in today's society. Herein, a stable and environmentally friendly nanofibrous membrane with hierarchical caterpillar-like structure was fabricated via in-situ hydrothermal growing the nickel-cobalt layered double hydroxides (NiCo-LDHs) on tche polyacrylonitrile (PAN) electrospun nanofibers. The wrapped hydrophilic NiCo-LDHs constructed the hierarchical structure and endowed the membrane attractive superhydrophilicity (≈ 0°)/underwater superoleophobicity (≈ 161°) and enhanced oil-repellency performance. Meanwhile, the NiCo-LDH@PANI/oPAN NFMs can display the ultra-fast flux of SSEs (xylene/water emulsion, 4175 L m−2 h−1) and satisfactory separation efficiency (99.07%). Moreover, the introduction of positively charged NiCo-LDHs increased plentiful adsorption active sites for membranes, which is beneficial to demulsify ionic SSEs and adsorb organic pollutants. Finally, for simultaneous purification of complex sewage by the dead-end and cross-flow filtration experiment, the composite membrane both displayed splendid removal rate of oil (> 99.0%) and dyes (> 99.0%), robust regeneration recycle-ability and no secondary pollution. Hence, it is expected that such strategy of combining electrospun and chelating-assisted in-situ hydrothermal can provide a low energy consumption and high decontamination technology for severe environmental crisis.

3D NiCo-Layered double Hydroxide@Ni nanotube networks as integrated free-standing electrodes for nonenzymatic glucose sensing

Nickel cobalt layered double hydroxide (NiCo-LDH)-based materials have recently emerged as catalysts for important electrochemical applications. However, they frequently suffer from low electrical conductivity and agglomeration, which in turn impairs their performance. Herein, we present a catalyst design based on integrated, self-supported nickel nanotube networks (Ni-NTNWs) loaded with NiCo-LDH nanosheets, which represents a binder-free, hierarchically nanostructured electrode architecture combining continuous conduction paths and openly accessible macropores of low tortuosity with an ultrahigh density of active sites. Similar to macroscale metallic foams, the NTNWs serve as three-dimensionally interconnected, robust frameworks for the deposition of active material, but are structured in the submicron range. Our synthesis is solely based on scalable approaches, namely templating with commercial track-etched membranes, electroless plating, and electrodeposition. Morphological and compositional characterization proved the successful decoration of the inner and outer nanotube surfaces with a conformal NiCo-LDH layer. Ni-NTNW electrodes and hydroxide-decorated variants showed excellent performance in glucose sensing. The highest activity was achieved for the catalyst augmented with NiCo-LDH nanosheets, which surpassed the modification with pure Ni(OH)2. Despite its low thickness of 20 µm, the optimized catalyst layer provided an outstanding sensitivity of 4.6 mA mM−1 cm−2, a low detection limit of 0.2 µM, a fast response time of 5.3 s, high selectivity and stability, and two linear ranges covering four orders of magnitude, up to 2.5 mM analyte. As such, derivatized interconnected metal nano-networks represent a promising design paradigm for highly miniaturized yet effective catalyst electrodes and electrochemical sensors.

Synergy effect of Ag plasmonic resonance and heterostructure construction enhanced visible-light photoelectrochemical sensing for quercetin

A novel heterojunction, on the basis of Ag doped zinc oxide nanorods (Ag–ZnO NRs) coupled with nickel cobalt layered double hydroxides (NiCo-LDHs), has been designed and prepared via a hydrothermal method followed by electrodeposition technique on F-doped SnO2 conducting glass (FTO) substrates. The morphology, compositions, optical and photoelectrochemical (PEC) performance were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, UV–vis spectroscopy, infrared spectroscopy, photoluminescence spectroscopy and PEC technique. The prepared NiCo-LDHs/Ag-ZnO NRs/FTO electrode exhibited a significantly enhanced PEC activity owing to the synergy effect of the surface plasmonic resonance of Ag nanoparticles and the heterostructure construction. The as-prepared electrode showed enhanced PEC quercetin (Qu) sensing performance under visible light irradiation. A broad linear range for Qu was obtained in the range of 1.0 × 10−10~5.0 × 10−6 mol/L and the detection limit was lowered to 0.075 nmol/L. Additionally, the PEC sensing platform for Qu exhibited advanced performances with high selectivity, good reproducibility and stability. The present work provides a new approach for the design of a PEC sensor for the detection of Qu in the practical applications.

Three dimensional hierarchical porous nickel cobalt layered double hydroxides (LDHs) and nitrogen doped activated biocarbon composites for high-performance asymmetric supercapacitor

Nitrogen-doped activated biocarbon (AC) and nickel-cobalt layered double hydroxides (LDHs) composites (NixCo1−x LDH/AC) are prepared by solvothermal method at various Ni/Co molar ratios. 3D nanoflowers composed of LDH nanosheets are spontaneously grown on the surface of AC from bio-waste, providing a suitable structure for the diffusion and transport of electrolyte ions. Ni0.5Co0.5LDH/AC composite electrode has high specific capacitance of 947 F g−1 at the current density of 1 A g−1, which could be explained by the synergistic effect of LDHs and AC. Furthermore, symmetric coin-cell AC//Ni0.5Co0.5 LDH/AC supercapacitor is assembled using Ni0.5Co0.5 LDH/AC composite as the cathode, and the pristine AC as the anode. Within 1.6 V voltage range, the supercapacitor device shows a maximum capacitance values (Csc) of 112 F g−1 at 1 A g−1. The developed asymmetric supercapacitor exhibits excellent rate performance and good cycle stability reflected through the maintenance of 80% of the initial Csc after 5000 consecutive cycles. Moreover, high energy density (39.7 Wh kg−1) is observed at low power density of 0.8 kW kg−1, and maintained at relatively high value (22.2 Wh kg−1) at high power density (16 kW kg−1). All these data indicate the potential applicability of AC//Ni0.5Co0.5 LDH/AC asymmetric supercapacitor for energy storage.

3D self-supporting heterostructure NiCo-LDH/ZnO/CC electrode for flexible high-performance supercapacitor

Two kinds of nanostructured ZnO, namely nanorods (ZnO NR) and nanoflakes (ZnO NF) were first prepared on conductive flexible carbon cloth (CC) by a hydrothermal route. Then nickel cobalt layered double hydroxide (NiCo-LDH) nanoflakes were directly hydrothermally deposited on them to construct three-dimensional (3D) self-supporting heterostructure NiCo-LDH/ZnO NR/CC and NiCo-LDH/ZnO NF/CC flexible electrodes. The effects of different nanostructured ZnO on morphology, structure and electrochemical performance of NiCo-LDH/ZnO/CC composite materials were investigated. It is found that NiCo-LDH nanoflakes grown on ZnO NF/CC substrate are more compact and uniform than those on ZnO NR/CC substrate. Moreover, NiCo-LDH/ZnO NF/CC electrode presents better electrochemical properties than NiCo-LDH/ZnO NR/CC electrode with 2.6 times higher specific capacitance (1577.6 F g−1 at 1 A g−1), 2.2 times better rate capability, and 1.5 time greater cycle stability, which may be attributed to the larger contact area and more redox-active sites provided by the NiCo-LDH NFs grown on ZnO NFs. Furthermore, the as-assembled solid-state flexible NiCo-LDH/ZnO NF//AC (active carbon) asymmetric supercapacitor (ASC) delivers a maximal energy density of 51.39 Wh kg−1 (800 W kg−1) with a high operating window of 1.6 V, and exhibits great cyclic stability with 87.3% capacitance retaining after 1000 cycles, which is higher than many reported ASCs. Finally, two packaged ASCs in series successfully lighted a red light-emitting diode (LED, 2.2 V/20 mA), evincing the potentiality of practical application.

Synthesis of reduced graphene oxide supported nickel-cobalt-layered double hydroxide nanosheets for supercapacitors

Supercapacitors are deemed as reliable power sources for portable devices and electric vehicles. Electrode materials with high energy and power densities are greatly needed. Herein, we designed reduced-graphene-oxide supported nickel-cobalt layered double hydroxide nanosheets (NiCo-LDH/rGO) as electrode materials. The introduction of graphene could largely enhance the conductivity, and the supported NiCo-LDH could effectively prevent graphene from self-aggregation. Thanks to the synergistic effect of conductive graphene and electro-active LDH, the nanocomposites delivered a capacitance of 1675 F g−1 at 1 A g−1 and decent rate performance (capacitance retention of 83.8% at 10 A g−1); while NiCo-LDH could only exhibited a capacitance of 920 F g−1 at 1 A g−1 and 81.5% of the capacitance remained at 10 A g−1. The asymmetric supercapacitors assembled with NiCo-LDH/rGO and activated carbon (AC) delivered high energy density and power density, up to 49.9 Wh kg−1 and 3747.9 W kg−1, respectively. The appealing electrochemical performance indicates its huge application potential in supercapacitors.

One-step hydrothermal synthesis of flower-like MnO2–NixCo1−x(OH)2@carbon felt positive electrodes with 3D open porous structure for high-performance asymmetric supercapacitors

In this study, nickel–cobalt-layered double hydroxides nanosheets combined with manganese dioxide directly coated on the carbon felt (MnO2–NixCo1−x(OH)2@CF) are prepared by a facile and novel one‐step hydrothermal process with the help of potassium permanganate (KMnO4). The CF not only plays the role of 3D open porous skeleton and current collector, but also serves as the reducing agent and anchor sites to generate OH− and MnO2 coated on the surface of CF by in situ reacting with KMnO4. The morphology and electrochemical performance of the as-prepared MnO2–NixCo1−x(OH)2@CF electrodes with different feeding molar ratio of Ni–Co are investigated and the optimum feeding molar ratio of Ni–Co is confirmed to be 8:2. The resulted MnO2–Ni0.8Co0.2(OH)2@CF electrode with a 3D open porous structure contains a large number of interconnected MnO2–Ni0.8Co0.2(OH)2 nanosheets and well-defined flower-like aggregations, which exhibits a high areal specific capacitance of 1018.6 mF cm−2 at 4 mA cm−2. Furthermore, the asymmetric supercapacitor based on the MnO2–Ni0.8Co0.2(OH)2@CF as the positive electrode and activated carbon-coated CF as the negative electrode has a maximum energy density of 49.5 μWh cm−2 and remarkable cycling stability (70.2% retention after 10,000 cycles at 20 mA cm−2).

Sulfur-Doped Nickel–Cobalt Double Hydroxide Electrodes for High-Performance Asymmetric Supercapacitors

In this work, an effective strategy was proposed to improve the electrochemical performance of nickel–cobalt layered double hydroxide (NiCo-LDH) by controlling the sulfur doping. The prepared NiCo-...

Advanced core-shell nanostructures based on porous NiCo-P nanodiscs shelled with NiCo-LDH nanosheets as a high-performance electrochemical sensing platform

The development of robust and efficient earth-abundant electrocatalysts based on complex core-shell arrays with ordered two-dimensional nano-architectures for different electrochemical technologies is an ongoing challenge. In this matter, the fabrication of core-shell arrays with a core of bimetallic phosphides nanodisc-like building blocks has not been reported yet. Herein, advanced core-shell nanostructures consisting of porous nickel-cobalt phosphide nanodiscs (NiCo-P NDs) shelled with nickel-cobalt layered double hydroxide nanosheets (NiCo-LDH NSs) were rationally designed (NiCo-P@NiCo-LDH). The NiCo-P@NiCo-LDH core-shell nanodiscs/nanosheets have unique features such as high conductivity, large specific surface area, more contact area between nanomaterials and analyte, and numerous active sites for enhancing electrochemical performance. The electrocatalytic performance of fabricated core-shell arrays was evaluated toward electrochemical sensing of isoprenaline (IPN) as a templet. Some competencies of glassy carbon electrode coated with NiCo-P@NiCo-LDH core-shell arrays (NiCo-P@NiCo-LDH/GCE) to IPN determination are including speedy response time (∆t <1s), low detection limit (0.17 µM), wide linear range (0.5–2110 µM), long-term stability, good reproducibility, low cost, and portability. This report is promising for application in other electrochemical technologies and it will pave the way for the development of new core-shell nanostructures based on multi-metallic phosphide nanodiscs.

Efficient degradation of organic dye using Ni-MOF derived NiCo-LDH as peroxymonosulfate activator

Nickel-based metal-organic framework (Ni-MOF) was employed as a sacrificial template for the preparation of nickel-cobalt layered double hydroxide (NiCo-LDH) under different hydrolysis time. The template etching rate varied at different hydrolysis time, resulting in variations of the structural and morphology of NiCo-LDHs. The NiCo-LDH/10 sample showed a large specific surface area and the well-oriented larger dimension of thinner sheets due to the sufficient in-situ etching of the Ni-MOF template. The NiCo-LDH/10 was an excellent heterogeneous catalyst to activate peroxymonosulfate (PMS) for highly efficient Reactive Red-120 dye degradation. The results exhibited that the degradation efficiency of the NiCo-LDH/10-PMS catalyst was 89% for RR-120 dye within 10 min in the presence of the PMS system, which is higher than other NiCo-LDHs. Moreover, the other influencing factors such as PMS concentration, catalyst dosage, initial pH were also investigated towards degradation. The radical quenching measurement proved that the sulfate (SO4•−) and hydroxyl (OH•) had been indicated as the primary radicals. Besides, the NiCo-LDH/10-PMS catalyst showed excellent reusability even after five consecutive cycles (83.6% of the degradation efficiency). This work offer insight study on the construction of controlled morphology NiCo-LDH heterogeneous structure for high-efficiency PMS activation.

Hierarchical molybdenum disulfide nanosheet arrays stemmed from nickel-cobalt layered double hydroxide/carbon cloth for highly-efficient hydrogen evolution reaction

The hierarchical molybdenum disulfide nanosheet arrays on carbon cloth are synthesized using layered double hydroxides as a growth template for highly efficient hydrogen evolution reaction. The hierarchical structure of molybdenum disulfide (MoS 2 ) nanosheet arrays stemmed from nickel-cobalt layered double hydroxide (NiCo-LDH)/carbon cloth was prepared by growing the MoS 2 nanosheet arrays onto the NiCo-LDH template which was pre-deposited onto the carbon cloth substrate. In this electrode configuration, carbon cloth is the three dimensional and conductive skeleton; NiCo-LDH nanosheets, as the template, ensure the oriented growth of MoS 2 nanosheet arrays. Therefore, more MoS 2 active sites are exposed and the catalyst exhibits good hydrogen evolution reaction activity.

Highly sensitive nonenzymetic glucose sensing based on multicomponent hierarchical NiCo-LDH/CCCH/CuF nanostructures

A highly sensitive nonenzymetic electrochemical glucose sensor was developed by using a multicomponent sensing electrode made of nickel cobalt layered double hydroxide (NiCo-LDH) and cobalt copper carbonate hydroxide (CCCH) hierarchical nanostructure on Cu foam (NiCo-LDH/CCCH/CuF). The results of electrochemical measurements show that both the large accessible surface area of hierarchical nanostructure and the good conductivity of Cu foam are in favor of electrocatalysis so that the glucose detection. We have systematically evaluated the catalytic performance of NiCo-LDH/CCCH/CuF systems by changing the Ni:Co mole ratio and the synthesis time based on both cyclic voltammetry and amperometry techniques. Our results indicate that the optimization NiCo-LDH/CCCH/CuF system exhibits high sensitivity (10.78 μA/μM/cm2), large linear concentration range (0.0011.5 mM) and fast response-recovery times (2.4 s and 2.0 s) for glucose analyses. By integrating the NiCo-LDH/CCCH/CuF glucose sensing electrode with the custom-printed circuit board (PCB), we also demonstrate the feasibility of glucose detection at micromole level. Therefore, the NiCo-LDH/CCCH/CuF hierarchical nanostructure is applicable to the high sensitivity glucose determination.

Rational construction of MOF derived hollow leaf-like Ni/Co(VO3)x(OH)2-x for enhanced supercapacitor performance

It is well known that the elements doping and morphology adjusting strategy are an effective ways to enhance the performance of supercapacitor electrode materials. In this work, using a Co-MOF as a precursor, a series of hollow-porous leaf-like V-doped nickel-cobalt layered double hydroxides (Ni-Co/V) nanosheets are successfully fabricated through a step-to-step etching process. The optimized Ni-Co/V-12-2 hollow leaf-like structure presents a typical hierarchical structure constructed by ultra-thin nanosheets and a hybrid pore of micro-/meso-porous with a BET surface area of 126.3 m2 g−1, which will provide the more active site and rich diffusion channels for enhanced energy storage performance. Therefore, the Ni-Co/V-12-2 electrode exhibits a high capacity of 161.4 mAh g−1 at 1 A g−1 and excellent cycle stability of maintaining 93.14% after 5600 cycles. Moreover, a hybrid supercapacitor with the Ni-Co/V-12-2 as the positive electrode and reduced graphene oxide (PPD/rGO) as the negative electrode, performs a high energy density of 55.22 Wh kg−1 at the power density of 0.375 kW kg−1.

Hydrolysis of metal-organic framework towards three-dimensional nickel cobalt-layered double hydroxide for high performance supercapacitors

Layered double hydroxide (LDH) is commonly employed as supercapacitor electrode due to its high theoretical and experimental capacitance, but limited by its easily agglomerated structure. Herein, a three-dimensional nickel cobalt-layered double hydroxide on carbon fiber cloth (NiCo-LDH/CFC) is synthesized via an in-situ hydrolysis of Co-based metal organic framework array (Co-MOF) for supercapacitors. Both the metal sites and overall morphology of Co-MOF are well maintained inner NiCo-LDH/CFC, providing sufficient active sites and rapid diffusion kinetics for charge storage. Consequently, an optimal specific capacitance of 2685 F g−1 (1074 C g−1) is achieved for NiCo-LDH/CFC electrode, higher than that of powdered NiCo-LDH (1352 F g−1 or 540.8 C g−1). Moreover, a hybrid supercapacitor is assembled with NiCo-LDH/CFC as positive electrode and active carbon as negative electrode. The hybrid device exhibits a high energy density of 64.9 Wh kg−1, a maximum power density of 16.9 kW kg−1, and long cycling stability (82.7% capacitance retention after 3000 cycles). These results indicate the great potential of in-situ hydrolysis of MOFs for high performance energy storage electrode materials.

Construction of polypyrrole nanotubes interconnected ZIFs-templated nickel-cobalt layered double hydroxide via varying the mass of ZIF-67 for supercapacitors with tunable performance

Reasonable construction of electrodes materials with heterostructures is a very effective way to enhance the electrochemical performance. Herein, a series of hybrid electrodes materials (PPy/Ni–Co LDH) based on nickel-cobalt layered double hydroxide (Ni–Co LDH) with zeolitic imidazolate framework-67 (ZIF-67) as the template and polypyrrole (PPy) nanotubes have been synthesized. Various precursors PPy/ZIF-67 based on polypyrrole nanotubes with the same amount have been prepared, where the mass ratio of polypyrrole nanotubes to ZIF-67 are varied in the process of crystallization. As-synthesized precursors PPy/ZIF-67 serve as sacrificial templates and give birth to various hybrid electrodes materials PPy/Ni–Co LDH with the core-shell structure, where Ni–Co LDH is closely coated on the external surface of polypyrrole nanotubes. The experimental findings reveal the electrochemical performance of PPy/Ni–Co LDH becomes better and better with increasing masses of Ni–Co LDH. Benefiting from their core-shell structure and the synergy effect between polypyrrole nanotubes and Ni–Co LDH, the optimized sample displays a specific capacitance of 13.0 F cm−2 (1858.3 F g−1) at 1 mA cm−2 and a favorable rate capability. Furthermore, a symmetric coin-type hybrid supercapacitor based on the optimized sample has also been fabricated, and exhibits an energy density of 10.425 mWh·cm−2 at the power density of 0.25 mW cm−2.

Hierarchical dense Ni−Co layered double hydroxide supported carbon nanofibers for the electrochemical determination of metronidazole in biological samples

Scientific research reports have shown that long-term use of chemical and biological drugs such as Metronidazole (MNZ) can lead to certain human health issues due to its genotoxic, genotypic, carcinogenic and mutagenic type side effects in the biological samples. Therefore, the rapid exploration and rational design of electrocatalyst materials, reliable electrochemical techniques, and essential strategies to fabricate novel electrochemical sensing devices for the detection of drugs in the biological samples are of utmost interest. Herein, we developed a facile strategy to fabricate a novel electrode material consisting of conductive hierarchical dense nickel-cobalt layered double hydroxide material grown on electrospun carbon nanofibers (CNF–NiCo-LDH), which was synthesized via a simple hydrothermal method. Because of their hierarchical dense unique interconnected architecture, the CNF–NiCo-LDH deposited onto a glassy carbon electrode (GCE) exhibited improved electrocatalytic response toward metronidazole (MNZ). The fabricated electrode delivered a higher cathodic peak current for MNZ at a low peak potential of −0.54 V in the presence of 20 μM MNZ in 0.05 M phosphate-buffered solution ((PBS; pH 7). The fabricated electrode showed a wide linear response for the reduction of MNZ at concentrations from 3 to 57 nM, an extremely lower detection limit (LOD) of 0.13 nM, and a high sensitivity of 1.294 μA nM−1 cm−2. The developed electrode also showed interference-free sensing performance and excellent long-term stability. Because of its electrochemical performance, the CNF–NiCo-LDH-GCE provides a simple, fast, and effective electrochemical sensor for the detection of MNZ at the ultra-trace level in industrial and pharmaceutical applications.

3D flower-like NiCo-LDH composites for a high-performance NO2 gas sensor at room temperature

Excellent response with a fast response/recovery time, as well as good repeatability and longtime stability, are considered to be advantageous features of an ideal gas sensor. To this purpose, in this paper, uniform 3D flower-like layered nickel-cobalt layered double hydroxide (NiCo-LDH) composites were prepared by a simple hydrothermal method. The gas sensing performance of the NiCo-LDH NO2 gas sensors was investigated at room temperature (RT). Among the composites, Ni1Co1 (Ni/Co molar ratio = 1:1) shows a high response of 31.22 at 100 ppm with fast response and recovery times equal to 1.6 s and 11.6 s, respectively. Similarly, the Ni1Co1 sensor indicates a low detection limit of only 0.01 ppm (10 ppb) and shows excellent stability (60 days) and high selectivity to NO2. The NiCo-LDH sensor has excellent NO2 gas sensitivity performance due to its a high specific surface area or Co(OH)2 and Ni(OH)2 synergy. Therefore, we believe that Ni/Co-LDH sensors can be widely used in the field at RT and have good development prospects.