Bimetal Metal-organic Frameworks Research Articles

The reconstruction of equal-mole bimetal organic framework to heterostructure for effective oxygen evolution reaction

Oxygen evolution reaction (OER) is one of the most important issues for hydrogen production from water splitting. During the OER process, electrochemical reconstruction is widely observed for the majority of electrocatalysts, which is strongly related to the formation and evolution of real active species. Herein, bimetal metal-organic framework (MOF) with an equal ratio of Co and Fe sites is screened to exhibit the superior OER property. An obvious reconstruction is observed to transform single MOF phase into the heterostructure composed of active CoOOH and FeOOH. Meanwhile, the generation of Co3+ species is more reliant on the blessing of electricity and electrolyte than that of Fe3+ species. As a result, the optimal electrocatalyst shows the overpotential of 267 mV at 10 mA/cm2 and ultra-low Tafel slope of 24.7 mV/dec with a stable OER performance.

MOFs-derived Co-Fe sulfides as highly efficient and stable catalysts to activate peroxymonosulfate for the degradation of trichlorophenol

Advanced oxidation processes activated by transition metal have attracted much attention for their excellent performance in the removal of organic pollutants, but the development of efficient and environmentally benign catalysts is still a significant challenge. In this work, carbon shell encapsulating Co/Fe sulfide nanoparticles (Co/Fe@SCX) were synthesized by pyrolysis of the resorcinol-formaldehyde (RF) coated MIL-101 @ZIF-67 bimetal Metal-organic frameworks (MOFs). In the degradation of TCP, Co/Fe@SC600 exhibited the highest TCP removal rate (97.33%) and reaction rate constant (kobs) (0.169 min−1), as well as the mineralization rate of up to 60.19%. Compared to other prepared catalysts, Co/Fe@SC600 not only possessed excellent catalytic activity, but also exhibited the lowest Co ion leaching concentration, good stability and high resistance to environmental factors. Further studies showed that the non-radical pathway dominated by 1O2 contributed most to the TCP degradation, and the radicals also played the indispensable role. The potential TCP degradation pathways in the reaction system was also investigated by analyzing the intermediate products during the degradation process. Overall, this study may provide some interesting insights into the design of advanced catalysts.

Fe-Cu bimetal metal-organic framework for efficient decontamination via Fenton-like process: Synthesis, performance and mechanism

Constructing Fe-Cu bimetal catalysts is an efficient strategy to promote Fe(III)/Fe(II) cycle, whereas there is still a long way to go before fully understanding the role of the Cu in the catalysts. Herein, a new Fe-MOF namely BUC-96(Fe) was fabricated from FeSO4·7H2O, 4,4′-bipyridine (bpy) and 2,5-dihydroxyterephthalic acid (H4dhtp) by both hydrothermal reaction and microwave-assisted method. Also, bimetal BUC-96(FeCu-x) were obtained when the CuSO4 was added into the system identical to the synthesis process of BUC-96(Fe). Series BUC-96 MOFs showed good organics elimination performance via Fenton-like process, where 88.1% (k = 0.0672 min−1) of chloroquine phosphate (CQ, 20 mg/L) was decomposed over pristine BUC-96(Fe) within 30 min. Interestingly, nearly 100% CQ was degraded over BUC-96(FeCu-5) as catalyst under the identical conditions within 5 min, whose reaction rate (1.3527 min−1) was 20.1-fold higher than that of BUC-96. Additionally, BUC-96(FeCu-5) exhibited excellent Fenton-like oxidation degradation performance for 10 selected emerging organic pollutants. The reaction mechanism was studied in detail by experiments, and density functional theory (DFT) calculation. The results revealed that the introduced Cu not only accelerated Fe(III)/Fe(II) cycles, hydroxyl radical (·OH) generation, electron transfer, but also lowered H2O2 dissociated energy barrier. This work advanced the bimetal MOFs construction and application in wastewater treatment via Fenton-like process.

Carbon polyhedra encapsulated Si derived from Co-Mo bimetal MOFs as anode materials for lithium-ion batteries

Silicon (Si) holds promise as an anode material for lithium-ion batteries (LIBs) as it is widely available and characterized by high specific capacity and suitable working potential. However, the relatively low electrical conductivity of Si and the significantly high extent of volume expansion realized during lithiation hinder its practical application. We prepared N-doped carbon polyhedral micro cage encapsulated Si nanoparticles derived from Co-Mo bimetal metal-organic framework (MOFs) (denoted as Si/CoMo@NCP) and explored their lithium storage performance as anode materials to address these problems. The Si/CoMo@NCP anode exhibited a high reversible lithium storage capacity (1013 mAh g−1 at 0.5 A g−1 after 100 cycles), stable cycle performance (745 mAh g−1 at 1 A g−1 after 400 cycles), and excellent rate performance (723 mAh g−1 at 2 A g−1). Also, the constructed the full-cell NCM811//Si/CoMo@NCP exhibited well reversible capacity. The excellent electrochemical performances of Si/CoMo@NCP were attributed to two unique properties. The encapsulation of NCP with doped nitrogen and porous structural carbon improves the electrical conductivity and cycling stability of the molecules. The introductions of metallic cobalt and its oxides help to improve the rate capability and lithiation capacity of the materials following multi-electron reaction mechanisms.

Modification of bimetal Zn/ Mg MOF with nanoparticles Fe3O4 and Fe3O4@SiO2, investigation of the peroxidase-like activity of these compounds by calorimetry and fluorimetry methods

In this article; the bimetal metal-organic framework Zn/Mg (Zn/Mg MOF) is synthesized.Then Zn/Mg MOF bimetal was combined with Fe3O4 and Fe3O4@SiO2, and composites of Fe3O4@ SiO2/MOF/Dextrin, Fe3O4@SiO2/MOF, Fe3O4@MOF/Dextrin and Fe3O4@MOF made. The peroxidase-like activity of these compounds was investigated and compared by calorimetric Resazurin (Rz) and O-phenylenediamine (OPD); (Rz-H2O2, OPD-H2O2) and fluorimetric Rz and terephtalic acid (TA); (Rz-H2O2, TA-H2O2). The Fe3O4@ MOF/Dextrin composite has the highest peroxidase-like activity. The effect factors (amount of pH (6), the values of TA (1.37 mM), H2O2 (0.025 mM), reaction time (8.15 min), and amount of Composite (116.67 mg)) to increase the catalytic activity of Fe3O4@ MOF/Dextrin measured by chemometrics method. The most suitable linear range of the calibration curve by the TA-H2O2 -Composite fluorimetric method is 1–600 μg L−1, and the detection limit is 2.27 μg L−1. The relative standard deviation (RSD%) for measuring concentration atropine 1 μg L−1 (n = 6) is 1.18%. Finally, from this system for measuring atropine extracted by the Liquid-liquid extraction (LLE) method in two types of plants, D. Innoxia north and west and D. stramonium north and west of Iran (118.25 μg L−1, 79.80 μg L−1) and (18.477 μg L−1, 9.27 μg L−1) used, respectively.

Trade-Off of Metal Sites in Fe-Ni Bimetal Metal-Organic Frameworks for Efficient CO2 Photoreduction with Nearly 100% CO Selectivity.

This work disclosed the trade-off effect of two metal sites, which display distinct, key functionalities in naturally occurring and artificial catalysts for developing an advanced CO2 reduction system. To exploit the metal-organic frameworks (MOFs) as advanced catalysts, we prepared a series of Prussian blue analogues (FeNix PBAs) of tunable Ni/Fe molar ratio without changing the oxidation state of Fe and Ni for use as a photocatalyst in the CO2 reduction reaction (CRR). The FeNi0.66 PBA gives a superior CO yield rate (14.28 mmol·g-1·h-1) with nearly 100% CO selectivity, but the PBA would be basically CRR-inactive without either Ni or Fe. Experimental and calculation studies demonstrate that Fe and Ni display distinct functionalities. Specifically, Fe is an efficient mediator that boosts the electron transfer both from the photosensitizer to FeNix PBA and from FeNix PBA to CO2, and Ni serves as the active site for CO2 adsorption and reduction. Intriguingly, when there is already sufficient Ni in the catalyst, further increase of the Ni content gives marginal gains in the CO2 adsorption affinity that cannot offset the weakened electron transfer due to the Ni excess. The findings can help advance the design of bimetallic MOF catalysts that mimic naturally occurring bimetallic catalysts.

Novel stylophora coral-like furan-based Ni/Co bimetallic metal organic framework for high-performance capacitive storage and non-enzymatic glucose electrochemical sensing

With the development of power supplies for wearable devices, electrode materials with dual functions have received extensive attention. Herein, we report a strategy of preparing stylophora coral-like Ni/Co bimetal metal organic framework (MOF) with furan-based derivatives as ligands through the simple solvothermal method, which can be utilized as a dual-function electrode material to build supercapacitors and non-enzymatic glucose sensing. It can be found that the high molecular stacking properties of the rigid furan ring skeleton combined with the unique stylophora coral-like morphology can greatly improve the charge transfer efficiency of the electrode reaction process, and the structure of the bimetallic node can effectively adjust the three-dimensional electronic structure, making high capacitive performance during charge storage. The specific capacitance of the furan-based bimetallic MOF material is as high as 531 C g−1 at a current density of 1 A g−1 with a high capacitance retention rate of 83.4% after 5000 cycles. In addition, the glucose sensing performance is analyzed and an outstanding sensitivity value of 366 µA mM−1 cm−2 is achieved with a low limit of detection (2 μM). The as-synthesized furan-based bimetallic MOF material is a promising candidate for electrochemical supercapacitors and efficient glucose detection.

Design of Pd-Zn Bimetal MOF Nanosheets and MOF-Derived Pd3.9Zn6.1/CNS Catalyst for Selective Hydrogenation of Acetylene under Simulated Front-End Conditions.

Novel zinc–palladium–porphyrin bimetal metal–organic framework (MOF) nanosheets were directly synthesized by coordination chelation between Zn(II) and Pd(II) tetra(4-carboxyphenyl)porphin (TCPP(Pd)) using a solvothermal method. Furthermore, a serial of carbon nanosheets supported Pd–Zn intermetallics (Pd–Zn-ins/CNS) with different Pd: Zn atomic ratios were obtained by one-step carbonization under different temperature using the prepared Zn-TCPP(Pd) MOF nanosheets as precursor. In the carbonization process, Pd–Zn-ins went through the transformation from PdZn (650 °C) to Pd3.9Zn6.1 (~950 °C) then to Pd3.9Zn6.1/Pd (1000 °C) with the temperature increasing. The synthesized Pd–Zn-ins/CNS were further employed as catalysts for selective hydrogenation of acetylene. Pd3.9Zn6.1 showed the best catalytic performance compared with other Pd–Zn intermetallic forms.

Morphology Control Strategy of Bimetallic MOF Nanosheets for Upgrading the Sensitivity of Noninvasive Glucose Detection.

The precise measurement of glucose level is significant for the health management of the human body. However, the existing sensitive materials and detection methods for glucose are less satisfying for practical applications. Herein, an ultrathin reticular two-dimensional nanosheets array composed of trimesic acid (H3BTC)-based bimetal metal-organic frameworks (MOFs) and carbon cloth (CC), which is constructed through a morphology control strategy, is reported for glucose sensing. Meanwhile, this nonmoving sweat glucose sensor based on a NiCo-BTC/CC electrode has been successfully prepared by a screen printing method. Benefiting from the regular and ultrathin nanosheets array, the NiCo-BTC/CC electrode has an excellent sensitivity of 2701.29 μA mM-1 cm-2, which is about 2.4 times that of its unregulated counterpart (1127.85 μA mM-1 cm-2) in the linear range 5-205 μM. In addition, an ultralow detection limit (0.09 μM, S/N = 3) and good selectivity of NiCo-BTC/CC were also obtained. The high sensitivity of the glucose sensor based on NiCo-BTC/CC electrode is 0.174 μA μM-1 (50-1000 μM). Remarkably, the preciously designed sensor is used to detect glucose concentration in sweat with a noninvasive mode, and the results are basically consistent with those of a commercial glucose device with an invasive mode. This research exhibits potential methodology for the morphology design of bimetallic MOFs nanosheets to achieve a high accuracy rate and noninvasive and timeless measurement of a glucose sensor.

Enhancing Hydrogen Adsorption Capacity of Metal Organic Frameworks M(BDC)TED0.5 through Constructing a Bimetallic Structure.

Metal organic frameworks (MOFs) have promising application prospects in the field of hydrogen storage. However, the successful application of MOFs in the field is still limited by their hydrogen storage capacity. Herein, a series of MxM1–x(BDC)TED0.5 (M = Zn, Cu, Co, or Ni) with a bimetallic structure was constructed by introducing two metal ions in the synthesis process. The results of X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma showed that the bimetallic structure with different content ratios can be stably constructed by a hydrothermal method. Among them, the Cu-based bimetal MOFs Cu0.625Ni0.375(BDC)TED0.5 exhibited the best hydrogen storage capacity of 2.04 wt% at 77 K and 1 bar, which was 22% higher than that of monometallic Ni(BDC)TED0.5. The enhanced hydrogen storage capacity can be attributed to the improved specific surface area and micropore volume of bimetal MOFs by introducing an appropriate amount of bimetallic atoms.

Cellular scaffolds based on multiwalled carbon nanotubes interpenetrating conductive metal-organic frameworks as efficient eelectrocatalysts in microbial fuel cells

Sluggish kinetics of the cathodic oxygen reduction reaction (ORR) is one of the major challenges hindering the development of microbial fuel cells (MFCs). In this work, a three-dimensional (3D) cellular scaffolds structure is fabricated by in-situ growth of conductive Ni/Co-catecholate bimetal metal-organic frameworks (MOFs) on multiwalled carbon nanotubes (NiCo-CAT/MWCNTs). Such specific structure successfully achieves favorable electronic channels and fast charge-transfer capacity and displays an ultra-low ohmic internal resistance of 7.27 Ω. Meanwhile, NiCo-CAT/MWCNTs exhibit a superior ORR half-wave potential (−0.442V vs. Hg/HgCl2), onset potential (−0.064V vs. Hg/HgCl2) and high limiting current density (8.25 mA cm−2), which exceed that of commercial Pt/C. In the MFC with the NiCo-CAT/MWCNTs cathode, the maximum power density is 130% higher than Pt/C cathode. The outstanding performance of MFC is mainly due to the optimized electronic structure and fully exposure of the Ni, Co synergistic catalytic active sites. In addition, oxygen permeability is greatly improved by electrospun polyvinylidene fluoride (PVDF) air diffusion layer replacing the traditional carbon cloth cathode. This study provides a new perspective for MFCs performance improvement by ORR conductive MOFs catalysts.

MOF-derived porous NiO/NiFe2O4 nanocubes for improving the acetone detection

Exploring sensing materials with superior catalytic properties is of paramount importance for acetone detection. In this work, NiO/NiFe2O4 nanocubes derived from Ni/Fe bimetal metal-organic frameworks (MOFs) precursors are synthesized by one-step impregnation method and subsequent annealing process. The microstructure and morphology of the synthesized samples are investigated by a series of characterization. The results indicate that uniform and porous NiO/NiFe2O4 nanocubes are formed. The gas sensing properties of NiO/NiFe2O4 composites are systematically evaluated. Benefitting from the synergistic effect of abundant sites, p-p junction and high surface area, the optimal sensors based on NiO/NiFe2O4 (Ni/Fe=1.5 at) exhibit the best sensing performance. The sensors show the highest response (19.9–100 pm acetone), short response/recovery times (2.4 s/19.6 s), low detection limit (200 ppb) and a good humidity tolerance ((S35% RH-S95% RH)/S35% RH= 0.095) to acetone at 200 °C. The results offer us a promising alternative to develop an ideal platform for acetone detection.

A facility synthesis of bismuth-iron bimetal MOF composite silver vanadate applied to visible light photocatalysis

The metal-organic framework (MOF)-based photocatalytic technology has received widespread attention due to its excellent properties (such as adjustable aperture structure and unique optical response). A facile sheet-like sliver vanadate/Bi–Fe MOF (AGV/HBF) heterojunction composite is successfully synthesized by introducing in situ precipitation AgVO3/Ag4V2O7 (AGV) nano-particles on the interface of Bi–Fe MOF. Herein, HBF is used as a template, and the morphology of the layer cake provides a suitable environment for the growth of nano-silver vanadate particles. The composite photocatalyst is characterized using XRD, FTIR, SEM, EDS, and XPS. HBF and AGV/0.25HBF worked well in the photocatalytic decomposition of rhodamine B (RhB) under visible light. The degradation efficiency reached 77.1% and 99.4% under visible light irradiation for 2 h, separately. The enhanced photocatalytic performance of the AGV/0.25HBF nanocomposite can be attributed to the strong visible-light absorption, unique nanostructures, and low recombination of electron-hole pairs due to the as-formed heterojunctions. In addition, the stability and photoelectric properties of HBF and AGV/0.25HBF are also discussed. Hope these studies can assist with the research and wide application of MOF-based photocatalysts.

Facile synthesis of ternary transition metal-organic framework and its stable lithium storage properties

Metal-organic frameworks (MOFs) are considered as promising electrode materials due to their high controllability and regular pore structure. Nevertheless, limited by the low ionic conductivity of organic frameworks and the huge volume change caused by the conversion reaction of metal ions with Li+, their long-term stability and rate performance are not satisfactory. In this paper, a regular micron rod-shaped nickel, iron and manganese benzene-1,2,4,5-tetracarboxylate trimetallic organic framework (NiFeMn-pma) was synthesized by a one-pot method. It belongs to monoclinic symmetry and P21/n space group, in which metal ions are coordinated with different oxygen atoms on the carboxyl group of pyromellitic acid to form a three-dimensional structure. Remarkably, thanks to the change of the lithium storage form from a conversion reaction to an intercalation reaction based on a carboxyl group and a benzene ring, NiFeMn-pma exhibits a high capacity of 802.1 mAh g-1 and excellent cycle stability (624 mAh g-1 at 100 ​mA ​g-1 over 100 cycles) as an anode material for lithium ion batteries (LIBs). Compared with single metal MOF (Ni-pma) and bimetal MOF (NiFe-pma), tri-metal MOF (NiFeMn-pma) exhibits enhanced rate performance, which is attributed to the synergistic effect of multi-metal mixing sites. Meanwhile, the surface of NiFeMn-pma electrode is porous after 100 cycles, which can significantly improve the penetration of electrolyte and promote the migration of lithium ions. The research paved the way for the potential application of MOF materials in lithium-ion batteries.

Design of hydrangea-type Co/Mo bimetal MOFs and MOF-derived Co/Mo2C embedded carbon composites for highly efficient oxygen evolution reaction

Transition metal organic framework (MOF)-derived catalysts are considered as promising electrocatalysts for the oxygen evolution reactions (OER) owing to their large surface area and abundant catalytic sites. However, to overcome the remaining limitations of their catalytic performance, it is imperative to develop catalysts with more efficient structure and sufficient intrinsic activity. Herein, we report a creative strategy for preparing efficient OER catalysts based on the Co/Mo MOFs with a two-dimensional (2D) hydrangea-type structure by employing molecular binders. In addition, these MOFs were successfully converted into hydrangea-type 2D Co/Mo2C heterostructure nanoparticles embedded in a N-doped carbon composite (H-2D Co/Mo2C@NC). Remarkably, H-2D Co/Mo2C@NC exhibited excellent OER performance with a low overpotential of 256 mV@η10 and a low Tafel slope of 48 mVdec−1. This can be attributed to the large accessible surface area of the nanoparticles owing to their hydrangea-type structure with open active sites and the modulation of the electronic structure of Co by Mo2C. This strategy will provide useful insights into the design of MOF-derived bimetal catalyst and heterojunction catalysts.

Bimetal metal-organic framework domino micro-reactor for synergistic antibacterial starvation/chemodynamic therapy and robust wound healing.

Antibacterial chemodynamic therapy (aCDT) has captured considerable attention in the treatment of pathogen-induced infections due to its potential to inactivate bacteria through germicidal reactive oxygen species (ROS). However, the lifespan of ROS generated by CDT is too short to achieve the efficacy of complete sterilization; thus, residual bacteria inevitably reproduce and cause super-infections. To address this concern, we devise an innovative bimetal, metal-organic framework (BMOF) domino micro-reactor (BMOF-DMR), consisting of Cu/Zn-rich BMOF and glucose oxidase (GOx), via electrostatic self-assembly. GOx catalyzes conversion of glucose into H2O2, and the Cu2+ ions then convert H2O2 into ˙OH to kill bacteria, thereby showing a domino effect. Accordingly, the BMOF-DMR not only blocks the nutrient/energy supply for bacteria, but also triggers a Fenton(-like) reaction and glutathione (GSH) depletion in a self-generating H2O2 microenvironment, all leading to high-efficiency bactericidal performance through synergistic starvation/chemodynamic therapy. Remarkably, in vitro and in vivo assessments demonstrate that the BMOF-DMR has superior cytocompatibility and exhibits robust ability to accelerate infectious full-thickness cutaneous regeneration through eradicating bacteria, promoting epithelialization of the wound beds and facilitating angiogenesis from the antibacterial activity and delivery of bimetal elements. The advantage of this antibacterial platform is that it suppresses bacterial metabolism by blocking the energy supply, which might prevent secondary infections from residual bacteria. As envisaged, the use of such a micro-reactor with starvation/chemodynamic therapy is a promising approach for combating bacterial skin wounds.

Bimetal NiCo-MOF-74 for highly selective NO capture from flue gas under ambient conditions.

The mixed bimetal metal-organic framework Ni0.37Co0.63-MOF-74 has been constructed by the solvothermal method for NO adsorption. The results showed that bimetal Ni0.37Co0.63-MOF-74 takes up NO with a capacity of up to 174.3 cc g-1 under ambient conditions, which is 16.3% higher than that of the best single metal Co-MOF-74. The IAST adsorption selectivity for a NO/CO2 binary mixture can reach a maximum of 710 at low adsorption partial pressure, while the regeneration performance can be retained even after five cyclic adsorption-desorption experiments. Its separation performance was further confirmed by breakthrough experiments, indicating this new bimetal Ni0.37Co0.63-MOF-74 as one of the best materials for NO adsorption and separation in flue gas.

Constructing 3D hierarchical MOFs nanospheres for oxygen evolution from high-throughput calculations

In order to realize outstanding electrochemical performance in oxygen evolution reactions (OER), it is important to construct 3D hierarchical nanospheres consisting of 2D bimetal metal–organic framework (MOF) nanosheets. Based on high-throughput density-functional theory (DFT) calculations, we chose Ni and V as central ions and prepared Ni-V bimetal MOFs nanospheres (NiV-MNs) assembled from ultrathin 2D MOFs nanosheets through a simple one-step solvothermal method. So far, V-based ultrathin 2D MOFs have been firstly reported. Gradient experiments demonstrated that NiV-MNs shows the best catalytic activity when the amount of Ni is equal to that of V (denoted as Ni1V1-MNs). The Ni1V1-MNs can deliver a high current density of 50 mA·cm−2 at a low over-potential of 370 mV in alkaline condition even after 10000 s continuous catalytic testing. Coincidentally, the DFT calculations further confirmed that the ΔG of Ni1V1-MNs is much lower compared with Ni1V2-MNs and Ni2V1-MNs. Based upon the experimental results and DFT calculations, we propose that the better performance of Ni1V1-MNs should be attributed to the grater intrinsic activity of Ni and the coupling effect between Ni and V, as they are crucial for tuning the electrochemical activity.

Hierarchical CuCo2O4@CoS-Cu/Co-MOF core-shell nanoflower derived from copper/cobalt bimetallic metal–organic frameworks for supercapacitors

Rational design of composite materials with unique core-shell nanoflower structures is an important strategy for improving the electrochemical properties of supercapacitors such as capacitance and cycle stability. Herein, a two-step electrodeposition technique is used to orderly synthesize CuCo2O4 and CoS on Ni foam coated with Cu/Co bimetal metal organic framework (Cu/Co-MOF) to fabricate a hierarchical core-shell nanoflower material (CuCo2O4@CoS-Cu/Co-MOF). This unique structure can increase the electrochemically active site of the composite, promoting the Faradaic redox reaction and enhancing its electrochemical properties. CuCo2O4@CoS-Cu/Co-MOF shows a prominent specific capacitance of 3150 F g−1 at 1 A g−1, marvelous rate performance of 81.82% (2577.3 F g−1 at 30 A g−1) and long cycle life (maintaining 96.74% after 10,000 cycles). What is more, the assembled CuCo2O4@CoS-Cu/Co-MOF//CNTs device has an energy density of 73.19 Wh kg−1 when the power density is 849.94 W kg−1. It has unexpected application prospects.

Novel ZIF67/Mn/MWCNTs decorated with layer double hydroxide supercapacitor electrodes

Nanoflakes of bimetal metal-organic framework (MOF) with different multiwall carbon nanotubes (MWCNTs) contents decorated by layer double hydroxide (LDH) (Ni-ZIF670.75(1-X%)/Mn0.25(1-X%)/MWCNTX%-LDH) were synthesized using solvothermal technique as supercapacitor electrodes. The structural properties, adsorption/desorption of surface area, porosity, morphology and elemental analysis of these nanocomposites were investigated by Fourier transforms infrared spectrum (FTIR), X-ray diffractometer (XRD), Brunauere-Emmett-Teller (BET) test, Barrett-Joyner-Halenda (BJH) test, scanning electronic microscope (SEM), and energy dispersive X-ray analysis (EDX), respectively. SEM image of Ni-ZIF6772.75%/Mn24.25%/MWCNT3%-LDH nanocomposite electrode showed an agglomeration of hollow nanoflakes shape of LDH with high porous structure and an average diameter of 1.15 µm. The electrochemical performance of the fabricated nanocomposites was assessed by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrical impedance spectroscopy (EIS). It was found that the Ni-ZIF6772.75%/Mn24.25%/MWCNT3%-LDH electrode provided a superior specific capacitance of 2395 Fg−1(1077 C/g) at 1 Ag−1 and 2732 Fg−1 (1639 C/g) at 5 mV/s. The stability of this electrode had capacitance retention of 92% after 1000 cycles with energy density of 70 Wh/kg and power density of 244 W/kg.