Ni-MOF Nanosheets Research Articles

Benzoic acid-modified 2D Ni-MOF for high-performance supercapacitors

Designing metal-organic frameworks (MOFs) with large specific surface area, high conductivity and abundant active sites are highly desirable for high-performance supercapacitors. Herein, the microstructure and electronic structure of NiMOF nanosheets were regulated by the partial substitution of dicarboxylic terephthalic acid (PTA) with monocarboxylic benzoic acid (BA), leading to high electronic conductivity and abundant electroactive sites of MOFs. The prepared NiMOF-10 nanosheets with 10 mol% BA substituting PTA exhibit the excellent electrochemical performance with a high specific capacity of 2.38 C cm−2 at 1 mA cm−2, and outstanding cycling stability (88% after 10,000 cycles). The fabricated hybrid supercapacitor (HSCs) demonstrated the maximum energy density of 50.1 Wh kg−1 at a power density of up to 2550 W kg−1. The exceptional electrochemical performance of NiMOF nanosheets is assigned to the improved electronic conductivity and abundant active sites induced by ligand exchange.

Self-supported 2D Fe-doped Ni-MOF nanosheets as highly efficient and stable electrocatalysts for benzylamine oxidation

Electrocatalytic water splitting is a competitive method to produce clean energy hydrogen, but it is largely limited by the slow anodic oxygen evolution reaction (OER). Replacing OER with low-thermodynamic oxidation process of benzylamine oxidation reaction (BOR) will significantly reduce energy consumption and produce economically beneficial chemicals simultaneously. Here we constructed self-supported 2D Fe-doped Ni-MOF nansheets on nickel foam (NiFe-MOF/NF) with precise control over Ni/Fe atomic ratios via a simple solvothermal method. When used as electrocatalysts for BOR, NiFe-MOF/NF shows an optimal performance with ultralow potential of 1.30 and 1.35 V at current densities of 10 and 100 mA cm−2 as well as accelerated electron transfer kinetics with an ultrasmall Tafel slope of 24.3 mV dec-1, which ranks among the top of BOR catalysts reported so far. The benzenitrile yield and Faraday efficiency reaches as high as 0.181 mmol mg−1h−1 and 99% with excellent stability. Such outstanding catalytic performances can be ascribed to the self-supported 2D nanosheets on 3D NF, hierarchical porous structure, abundant surface metallic sites, enhanced electrical conductivity and boosted synergy between metals after Fe doping. Our result suggests that such MOF catalysts are attractive for energy-saving water splitting and benzonitrile production.

Ni2P nanocrystals embedded Ni-MOF nanosheets supported on nickel foam as bifunctional electrocatalyst for urea electrolysis

It’s highly desired but challenging to synthesize self-supporting nanohybrid made of conductive nanoparticles with metal organic framework (MOF) materials for the application in the electrochemical field. In this work, we report the preparation of Ni2P embedded Ni-MOF nanosheets supported on nickel foam through partial phosphidation (Ni2P@Ni-MOF/NF). The self-supporting Ni2P@Ni-MOF/NF was directly tested as electrode for urea electrolysis. When served as anode for urea oxidation reaction (UOR), it only demands 1.41 V (vs RHE) to deliver a current of 100 mA cm−2. And the overpotential of Ni2P@Ni-MOF/NF to reach 10 mA cm−2 for hydrogen evolution reaction HER was only 66 mV, remarkably lower than Ni2P/NF (133 mV). The exceptional electrochemical performance was attributed to the unique structure of Ni2P@Ni-MOF and the well exposed surface of Ni2P. Furthermore, the Ni2P@Ni-MOF/NF demonstrated outstanding longevity for both HER and UOR. The electrolyzer constructed with Ni2P@Ni-MOF/NF as bifunctional electrode can attain a current density of 100 mA cm−2 at a cell voltage as low as 1.65 V. Our work provides new insights for prepare MOF based nanohydrid for electrochemical application.

Anchoring Ni-MOF nanosheet on carbon cloth by zeolite imidazole framework derived ribbonlike Co3O4 as integrated composite cathodes for advanced hybrid supercapacitors

Metal-organic frameworks (MOFs) and their derivatives as electrode materials for energy storage and conversion are intriguing. However, the in-situ uniformly and firmly growing metal-organic framework materials directly on conductive substrates is limited and still challenging. Herein, an effective strategy is presented by constructing a ribbonlike Co3O4 nanoarrays that derived from zeolite imidazole framework (ZIF) on carbon cloth as “fixed piles” for the in-situ solvothermal synthesis of Ni-MOF nanosheets. As a result, the Ni-MOF nanosheets closely distribute on the surface of the carbon cloth with fluffy structure, which favors exposure of more active sites and rapid diffusion of electrolyte ions. The as-fabricated integrated composite electrode (Co3O4@Ni-MOF) delivers a good specific capacitance of 1416 F/g at the current density of 1 A/g, superior to the individual Co3O4 (410 F/g) and Ni-MOF electrode (690 F/g). Moreover, the specific capacitance can be kept at 90% of its original value after 3000 cycles. Based on these advantages, a hybrid supercapacitor fabricated by the Co3O4@Ni-MOF electrode and activated carbon (AC) shows prominent energy density of 68.6 Wh kg−1 at the power density of 510 W kg−1, and excellent cycling stability (about 12% capacitance loss after 5000 charge-discharge cycles).

Hierarchical core-shell 2D MOF nanosheet hybrid arrays for high-performance hybrid supercapacitors.

Two-dimensional (2D) metal-organic frameworks (MOFs) with large surface area, ordered pores and ultrathin thickness have recently emerged as ideal electrode materials for supercapacitors (SCs). However, their straightforward applications are restricted by the drawbacks of self-stacking and unsatisfactory electrical conductivity. Herein, ultrathin Ni-MOF nanosheets have been grafted on zeolite imidazolate framework (ZIF-L)-derived porous Co3O4 nanosheets to form hierarchical core-shell Co3O4@Ni-MOF 2D nanosheet hybrid arrays. The porous Co3O4 "core" acts as a conductive skeleton for anchoring Ni-MOF and provides shortened ion diffusion paths. The Ni-MOF "shell" can expose large active sites. Benefiting from these merits and the synergic effects of the "core and "shell", the Co3O4@Ni-MOF/NF shows a high specific capacity (capacitance) of 225.6 mA h g-1 (1980.7 F g-1) at 1 A g-1 with decent capacitance retention (82.2% after 2000 cycles). The asymmetric two-electrode cell assembled from Co3O4@Ni-MOF/NF exhibits an energy density of 37.05 W h kg-1 at a power density of 800 W kg-1 with good long-term durability (75% capacitance retention after 10 000 cycles). Moreover, two charged cells can power a red light-emitting diode (LED) for up to 16 min, manifesting the great promise of Co3O4@Ni-MOF/NF for real energy storage devices.

Ultrathin Mn Doped Ni‐MOF Nanosheet Array for Highly Capacitive and Stable Asymmetric Supercapacitor

In this study, we demonstrate that an Mn-doped ultrathin Ni-MOF nanosheet array on nickel foam (Mn0.1 -Ni-MOF/NF) serves as a highly capacitive and stable supercapacitor positive electrode. The Mn0.1 -Ni-MOF/NF shows an areal capacity of 6.48 C cm-2 (specific capacity C: 1178 C g-1 ) at 2 mA cm-2 in 6.0 m KOH, outperforming most reported MOF-based materials. More importantly, it possesses excellent cycle stability to maintain 80.6 % capacity after 5000 cycles. An asymmetric supercapacitor device utilizing Mn0.1 -Ni-MOF/NF as the positive electrode and activated carbon as the negative electrode attains a high energy density of 39.6 Wh kg-1 at 143.8 Wkg-1 power density with a capacitance retention of 83.6 % after 5000 cycles.

Stretchable Electrochemical Biosensing Platform Based on Ni-MOF Composite/Au Nanoparticle-Coated Carbon Nanotubes for Real-Time Monitoring of Dopamine Released from Living Cells

Existing electrochemical biosensing platforms, using traditional rigid and unstretchable electrodes, cannot monitor the biological signaling molecules released by cells in a mechanically deformed state in real time. Here, a stretchable and flexible electrochemical sensor was developed based on nickel metal-organic framework composite/Au nanoparticle-coated carbon nanotubes (Ni-MOF composite/AuNPs/CNTs) for sensitive detection of dopamine (DA) released by C6 living cells in real time. A Ni-MOF composite was obtained by introducing Ni, NiO, and a carbon frame onto the surface of two-dimensional (2D) Ni-MOF nanosheets using an efficient one-step calcination method. The hybrid of Ni-MOF composite/AuNPs/CNTs that deposited on the poly(dimethylsiloxane) (PDMS) film endowed the sensor with excellent electrochemical performance with a wide linear range of 50 nM to 15 μM and a high sensitivity of 1250 mA/(cm2 M) and also provided the sensor with desirable stability against mechanical deformation. Furthermore, the stretchable electrode also displayed good cellular compatibility while C6 living cells can be cultured and proliferated on it with strong adhesion. Then, the DA released by C6 living cells with chemical induction in both natural and stretched states was monitored using our stretchable and flexible electrochemical sensor in real time. This indicates that our new design of flexible Ni-MOF composite/AuNPs/CNTs/PDMS (NACP) film electrodes provides more opportunities for the detection of chemical signals released from cells and soft living organisms even under mechanically deformed states.

Synthesis of Ni-MOF/Ti3C2Tx hybrid nanosheets via ultrasonific method for supercapacitor electrodes

Nickel-organic framework (Ni-MOF)/Ti3C2Tx (MXene) hybrid nanosheets as supercapacitor electrode materials are fabricated via a facile ultrasonic method. Ti3C2Tx nansheets are uniformly dispersed on the surface of Ni-MOF, thus enhancing the electronic conductivity and preventing the aggregation of Ni-MOF nanosheets. The as-prepared Ni-MOF/MXene hybrid nanosheets exhibit high specific capacitance of 867.3 F g−1 at 1 A g−1, and excellent rate capacity.

Self-assembled Mo doped Ni-MOF nanosheets based electrode material for high performance battery-supercapacitor hybrid device

The application of MOF materials in supercapacitors has been greatly restricted due to the poor conductivity and structural stability. Given that, this work improves the conductivity and stability of Ni-MOF by self-assembled strategy. We report here the Mo-doped Ni-MOF nanosheets (M-NMN), in which the Mo-based clusters are encapsulated in the holes of the Ni-MOF frame structure by self-assembly. The results show that the M-NMN-1 material with a Mi/Mo molar ratio of 1: 1 exhibits an excellent electrochemical performance. Furthermore, the nanosheet structure of the M-NMN-1 materials acts as a “superhigh way” for charge transport to accelerate charge transfer rate and enhance the conductivity of the electrode materials. As-prepared M-NMN-1 electrode material exhibits high specific capacity of 802 C g−1 at 1 A g−1. Furthermore, assembled battery-supercapacitor hybrid device exhibits an excellent energy density of 59 Wh kg−1 at a power density of 802 W kg−1, and superior cycle retention of 93% after 20,000 cycles.

Ni2P/C nanosheets derived from oriented growth Ni-MOF on nickel foam for enhanced electrocatalytic hydrogen evolution

Tuning the structural features that furnish electrochemically active sites with improved kinetic diffusion can provide an alternative way to achieve high performance of electrocatalysis. Here, we report a nano-structure of Ni2P/C(NPC) nano-sheets supported on nickel foam (NF) that is prepared by sequenced nitrogen pyrolysis and gas phosphatization of Ni-MOF nanosheets. Initially, the passivated surface of nickel foam facilitates the oriented growth of Ni-MOF nanosheets, which is crucial for the maintenance of structure stability during the subsequent pyrolysis and phosphatization treatment. As a result, more catalytic active sites are exposed than the non-oriented NPC catalysts and diffusion kinetics is favorable. Consequently, the obtained composite can exhibit excellent hydrogen evolution catalytic activity in an alkaline electrolyte. For hydrogen evolution reaction, a current density of 10 mA cm−2 is provided at an overpotential of 97 mV and its onset overpotential is only 29 mV. Meanwhile, good morphology and catalytic activity can be maintained after 12 h of stability testing. This excellent performance is believed to be the result of NPC nanosheet structure on NF derived from the facet-oriented control of pristine Ni-MOF, enabling excellent reaction kinetics.

A highly sensitive and stable electrochemiluminescence immunosensor for alpha-fetoprotein detection based on luminol-AgNPs@Co/Ni-MOF nanosheet microflowers

Due to their high catalytic effect on the electrochemiluminescence (ECL) of luminol, noble metal nanoparticles (NPs) have been widely used in luminol-based ECL immunosensors. However the aggregation of NPs often resulted in the decrease of ECL signal and affected the stability and durability of the sensor. In this study, a microflower-like structure made of ultrathin Co/Ni-based metal-organic frameworks (MOF) nanosheets were used as a platform for luminol-functionalized AgNPs to construct an immunosensor for tumor marker alpha-fetoprotein. The nanosheet and microflower-like assembly structure of the Co/Ni-MOF greatly improved the ECL performance of the luminol-AgNPs system, attributed to their large surface area, resistance to particle agglomeration and the high catalytic activity of the Co/Ni-MOF. The ultrathin Co/Ni-MOF was full of atomically dispersed cobalt ions and nickel ions, which can catalyze the ECL reaction of luminol and H2O2. The as-fabricated immunosensor has a good sensitivity with detection limit of 0.417 pg mL−1 (S/N=3), and shows satisfactory performance in practical applications.

A comparative study of electrocatalytic oxidation of glucose on conductive Ni-MOF nanosheet arrays with different ligands

A glucose sensor based on conductive Ni-MOF nanosheet arrays/CC exhibits a fast response time, a low detection limit, a high sensitivity, and it can also be applied for the detection of glucose in human serum samples.

A new promising Ni-MOF superstructure for high-performance supercapacitors.

A new layered structural Ni-MOF nanosheet has been successfully synthesized and used for the first time as an electrode for a supercapacitor and a flexible all-solid-state asymmetric supercapacitor, exhibiting capacitances of 1518.8 F g-1 at 1 A g-1 and 244 mF cm-2 at 0.5 mA cm-2, respectively.

In situ growth of well-aligned Ni-MOF nanosheets on nickel foam for enhanced photocatalytic degradation of typical volatile organic compounds.

Exploitation of highly efficient catalysts for photocatalytic degradation of volatile organic compounds (VOCs) under visible light irradiation is highly desirable yet challenging. Herein, well-aligned 2D Ni-MOF nanosheet arrays vertically grown on porous nickel foam (Ni-MOF/NF) without lateral stacking were successfully prepared via a facile in situ solvothermal strategy. In this process, Ni foam could serve as both a skeleton to vertically support the Ni-MOF nanosheets and a self-sacrificial template to afford Ni ions for MOF growth. The Ni-MOF/NF nanosheet arrays with highly exposed active sites and light harvesting centres as well as fast mass and e- transport channels exhibited excellent photocatalytic oxidation activity and mineralization efficiency to typical VOCs emitted from the paint spray industry, which was almost impossible for their three-dimensional (3D) bulk Ni-MOF counterparts. A mineralization efficiency of 86.6% could be achieved at 98.1% of ethyl acetate removal. The related degradation mechanism and possible reaction pathways were also attempted based on the electron paramagnetic resonance (EPR) and online Time-of-Flight Mass Spectrometer (PTR-ToF-MS) results.

Nickel metal–organic framework nanosheets as novel binder-free cathode for advanced fibrous aqueous rechargeable Ni–Zn battery

Ni-MOF nanosheets prepared via a facial and green hydrothermal method act as a novel binder-free cathode for a fibrous aqueous rechargeable Ni–Zn battery.

The flammability and mechanical properties of poly (lactic acid) composites containing Ni-MOF nanosheets with polyhydroxy groups

This work reports our recent effort on the preparation of α-Phenyl-N-(2-propyl-2-hydroxymethyl-1, 3-dihydroxy)-imine-Nickel (Ⅱ) (Ni-MOF) containing polyhydroxy groups and its application in improving the fire performance of PLA composites in combination with ammonium polyphosphate (APP). The flame retardant evaluation revealed that the presence of 1.7% Ni-MOF and 3.3% APP in PLA increased the LOI value to 31.0%, upgraded the UL-94 level to V-0, decreased the peak heat release rate (pHRR), total heat release (THR) and total smoking production (TSP) by 27%, 19% and 50%, respectively, and substantially delayed the time to ignition (TTI) from 67 to 97 s. It was proposed that the flame retardants take effect in both vapor and condensed phases, and Ni-MOF nanosheets can synergistically improve the flame resistance of PLA with APP. The incorporation of Ni-MOF effectively inhibited the deterioration of mechanical properties for PLA composites caused by the presence of APP.

Ultrathin Ni-MOF nanosheet coated NiCo2O4 nanowire arrays as a high-performance binder-free electrode for flexible hybrid supercapacitors

Metal–organic frameworks (MOFs) as a kind of novel electrode material for energy storage has attracted increasing attention. However, their poor conductivity and difficulties in directly grown on the current collector largely thwart their maximum performance. Herein, an effective strategy was developed to increase the overall electrical conductivity and active surface area of MOFs by implanting conductive NiCo2O4 nanowires on carbon cloth as the interconnected anchors for in situ growth of MOFs nanosheets. The as-synthesized NiCo2O4@Ni-MOF electrode delivers an ultra-high areal capacitance of 7.23 F cm−2 at a current density of 5 mA cm−2, with an exceptional rate capability (5.04 F cm−2 at a very high current density of 30 mA cm−2). Meanwhile, NiCo2O4 NWAs are used as the strain buffer supports for preparing core−shell NiCo2O4@PPy nanorod arrays as a negative electrode. As a result, an HSC is successfully assembled by using the NiCo2O4@Ni-MOF and NiCo2O4@PPy as electrodes, achieving both high volumetric capacitance and energy density. This study presents a versatile strategy for effectively fabricating MOFs based binder-free energy storage materials for future portable and wearable electronic devices.

Ultrathin Ni-MOF nanosheet arrays grown on polyaniline decorated Ni foam as an advanced electrode for asymmetric supercapacitors with high energy density.

Metal-organic frameworks (MOFs) have emerged as promising electrode materials for supercapacitors (SCs), due to their diverse functionalities and high porosity. However, the applications of MOFs in practical SC devices are restricted by their intrinsic low conductivity and poor stability. Herein, a thin layer of conductive polyaniline (PANI) was decorated on Ni foam (NF) before the growth of Ni-MOF to tackle these issues. PANI not only improves the conductivity but also promotes the formation of Ni-MOF nanosheet arrays and ensures good mechanical adhesion. The as-prepared Ni-MOF/PANI/NF exhibits a high areal capacitance (3626.4 mF cm-2 at 2 mA cm-2) and good rate capacity (71.3% at 50 mA cm-2). Moreover, an asymmetric supercapacitor (ASC) device using Ni-MOF/PANI/NF and activated carbon (AC) can deliver a maximum energy density of 45.6 W h kg-1 (850.0 W kg-1) with excellent cycling stability (capacitance retention of 81.6% after 10 000 cycles), outperforming most of the reported pristine MOF-based ASC devices.

Facile synthesis of ultrathin metal-organic framework nanosheets for Lewis acid catalysis

Ultrathin metal-organic framework (MOF) nanosheets are attracting great interest in catalysis due to their unique and intriguing two-dimensional (2D) features. Although many progresses have been achieved, it is still highly desirable to develop novel strategies for controllable synthesis of the well-defined ultrathin MOF nanosheets. Herein we report a polyvinylpyrrolidone (PVP)-assisted route to synthesize the ultrathin Ni-MOF nanosheets characteristic of 1.5 nm in thickness, in which PVP is reacted with 2-aminoterephthalic acid (H2BDC-NH2) via formation of C=N bond, followed by coordination with Ni2+ ions to form the ultrathin MOF nanosheets. Impressively, when used in the Knoevenagel condensation reactions of propane dinitrile with different aldehydes, ultrathin Ni-MOF nanosheets display the significantly enhanced catalytic activity and good stability in respect with the bulk Ni-MOF, mainly owing to the exposed active sites as well as facile mass transfer and diffusion of substrates and products.

Antimicrobial Activities of Green Synthesized Ag Nanoparticles @ Ni-MOF Nanosheets

Nanosheets of Ni-MOF loaded with green synthesized silver nanoparticles (Ag-NPs @ Ni-MOF) were prepared and tested for their antimicrobial potential. The as-prepared materials were characterized using X-ray diffraction (XRD), thermogravimetric analysis (TGA), field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and nitrogen adsorption/desorption at − 196 °C. The antibacterial activity of the prepared samples was tested against four different pathogenic microorganisms: Bacillus subtilis ATCC 6633 (Gram +ve bacteria), Escherichia coli ATCC 23282 (Gram −ve bacteria), Pseudomonas aeruginosa ATCC 10145 (Gram −ve bacteria), and Candida albicans IMRU 3669 (yeast pathogen). Ni-MOF showed antimicrobial activities, which were enhanced by loading green synthesized silver nanoparticles to Ni-MOF. The experimental results indicated 2.5 µg/mL Ag-NPs @ Ni-MOF could completely inhibit the growth of ~ 5 × 107 cfu/mL microbial cells in the culture medium. The results indicated that the disinfection properties of Ni-MOF toward microbes could be enhanced by loading traces of Ag-NPs.