Ni-based Metal-organic Framework Research Articles

Boron-doping induced electron redistribution of carbon-coated nickel nanoparticles towards efficient alkaline hydrogen evolution

Metal nickel (Ni) has been developed as hydrogen evolution reaction (HER) catalyst for water-alkali electrolyzers for almost a century. However, the catalytic efficiency and durability of metallic Ni is still far from satisfactory due to its inappropriate electronic structure and non-corrosion-resistant property. Herein, we report a facile strategy to fabricate the carbon-coated boron-doping nickel nanoparticles (Ni-B@C) via a convenient boronization and a subsequent carbonization treatment of the Ni-based metal organic framework (Ni2(OH)2(C8H4O4)). Such process also ensured the catalyst with high electrochemically active surface area. Particularly, the B-doping would induce the electron redistribution of Ni, resulting in optimized H2O dissociation and H* association, thereby significantly improving the alkaline HER kinetics. Benefiting from the contribution of these favourable properties, the as-prepared Ni-B@C catalyst exhibits remarkable alkaline HER activity with an overpotential of only 26 mV to reach a current density of 10 mA cm−2 and, more impressively, with superior durability in the constant-current test of 50 h at the different current densities of 10, 50 and 100 mA cm–2. The combination of these excellent characteristics clearly makes Ni-B@C catalyst stand out from existing competitors towards alkaline HER.

Facile prepared 2D Ni-based metal-organic framework nanosheets for boosting one-pot catalytic synthesis of cyclic carbonates

Two isostructural Ni-based MOF 2D nanosheets (NiBDC NS and NiBDC-NH2 NS) were facilely constructed by reflux method, which exhibited excellent activity for one-pot epoxidation-CO2 cycloaddition catalysis. Combining our activity evaluations, detailed kinetics and molecular simulation results, we revealed that the amino groups of these materials played a positive role in CO2 cycloaddition step but a negative role in epoxidation step. By using NiBDC NS, the conversion and yield of the targeted products under mild condition (80 °C, 1 bar and 12 h) could achieve 95% and 87%, respectively. The calculated Thiele modulus and effectiveness factor indicated that NiBDC NS exhibited a higher catalyst utilization degree with negligible diffusion constraint. We further confirmed the stability of these catalysts by repeatedly running the catalysis six times without observing significant loss of activity. Finally, the reaction mechanism was proposed by combining the results from experiment and simulations.

Synergy of charge capture and transfer by Ni-MOF nanosheets for enhancing energy storage performance of polyetherimide-based dielectric nanocomposites

Polymer-based dielectric nanocomposites with excellent energy storage performance and good thermal stability are essential to meet the demand for dielectric capacitors operating under high-temperature environments. However, there is still a challenge to high-temperature breakdown strength and energy density due to the increase in leakage current with temperature and applied electric field. In this work, Ni-based metal-organic framework nanosheets (Ni-MOFs) are synthesized by a sonication-assisted solution method and introduced into polyetherimide (PEI) to fabricate Ni-MOFs/PEI dielectric nanocomposites. As a result, the nanocomposites containing 2 wt. % Ni-MOFs exhibit a significantly enhanced breakdown strength of 640 kV/mm and a discharged energy density of 6.37 J/cm3 at 150 °C, which are 48% and 228% higher than those of pure PEI, respectively. This enhancement could be attributed to the synergistic effect of charge capture and transfer induced by wider bandgap and π–d conjugation of Ni-MOFs, which not only act as deep traps to capture charges at the interface but also transfer the charges along the in-plane direction to uniform the local electric field, thus reducing the leakage current and conduction loss. This work provides an effective strategy for the design of high-performance dielectric nanocomposites based on polymer.

Fire-safe epoxy composite realized by MXenes based nanostructure with vertically arrayed MOFs derived from interfacial assembly strategy

In this contribution, Ni-based metal organic frameworks (Ni-MOF) nanosheets with high specific surface area are grown on transition metals carbides (MXenes, denoted as MX) surface via vertical alignment, gestating the flame retardant of MX@MOF-B. With the addition of 2.0 wt% MX@MOF-B, the peak heat release rate, peak smoke production rate, peak CO production rate, peak CO2 production rate are reduced by 42.5 %, 26.7 %, 37.8 %, 54.9 %, while the peak concentrations of C2H6, CH4, HCN, NO, N2O are impaired by 91.3 %, 94.3 %, 89.6 %, 90.3 %, 60.9 %, suggesting the enhanced fire safety. Meantime, the fire performance index is elevated by 83.0 % and fire growth index is reduced by 37.2 %, demonstrating the promoted fire safety. Of note, the using of MX@MOF-B induces the promotion of 787.1 % in char yield after combustion, which shows higher graphitized degree and thus enables better protection for basal matrix. Flame retardation contrast with previous works also manifests the strength of MX@MOF-B in hindering the heat release and toxicants emission. This work offers a new paradigm for forging fire-safe polymer composites with low toxicity.

Ni(II)-Pyrazolate Framework Bearing a Metalated Schiff-Base Moiety for Electrocatalytic Hydrogen Evolution.

A robust and porous Ni-based metal-organic framework (MOF), NiL1, was assembled from Ni(II) ions and a dipyrazolate linker (L12-). A Ni(II)-anchored MOF catalyst Ni@NiL1-Sal has been successfully prepared by post-synthetic modification (PSM) condensation between NiL1 with salicylaldehyde, followed by chelation of Ni(II) ions by salicylaldimine as a secondary active site. Ni@NiL1-Sal with carbon black was found to exhibit enhanced electrocatalytic hydrogen evolution reaction (HER) performance (the smallest overpotential, 384 mV, and Tafel slope, 87 mV dec-1) when compared with primitive NiL1 and NiL1-Sal. Such improvement in HER highlights the creation of unambiguous secondary active sites as an avenue to the rational design of a functional MOF-based electrocatalyst.

Metal-organic framework derived r-Ni3S2 nanoparticles with enriched sulfur vacancies for supercapacitor application

Metal sulfides derived from metal-organic framework (MOF) have high porosity and easily changed morphology, so they are widely used in supercapacitors. However, they still have a few shortcomings such as poor cycle performance and low specific capacitance. The experiment shows that the generation of sulfur vacancy can optimize its electrochemical performance. Therefore, this work focuses on preparing porous nickel sulfide derived from Ni-based MOF and introducing sulfur vacancies at room temperature. Pleated nanoparticles of r-Ni3S2 that are composed of petal-like flakes were prepared with rich sulfur vacancies. This morphology has a larger specific surface area and sulfur vacancies also exposes more active sites, increases free charge carriers and reduces Gibbs free energy of surface reaction, which will enhance electrochemical performance. It is demonstrated that the specific capacitance increased significantly after the sodium borohydride reduction treatment, and the capacitance retention rate increased by 32 % after 5000 cycles. In addition, the asymmetric supercapacitor of r-Ni3S2//AC was assembled, which yielded a specific energy density of 33.7 Wh kg−1 at the power density of 1167.8 W kg−1. This research shows great potential in adjusting the crystal structure of compounds to optimize the advanced electrode materials of storage devices.

Hollow Ni/NiO/C composite derived from metal-organic frameworks as a high-efficiency electrocatalyst for the hydrogen evolution reaction

Metal-organic frameworks (MOFs) constitute a class of crystalline porous materials employed in storage and energy conversion applications. MOFs possess characteristics that render them ideal in the preparation of electrocatalysts, and exhibit excellent performance for the hydrogen evolution reaction (HER). Herein, H–Ni/NiO/C catalysts were synthesized from a Ni-based MOF hollow structure via a two-step process involving carbonization and oxidation. Interestingly, the performance of the H–Ni/NiO/C catalyst was superior to those of H–Ni/C, H–NiO/C, and NH–Ni/NiO/C catalysts for the HER. Notably, H–Ni/NiO/C exhibited the best electrocatalytic activity for the HER, with a low overpotential of 87 mV for 10 mA cm−2 and a Tafel slope of 91.7 mV dec−1. The high performance is ascribed to the synergistic effect of the metal/metal oxide and hollow architecture, which is favorable for breaking the H–OH bond, forming hydrogen atoms, and enabling charge transport. These results indicate that the employed approach is promising for fabricating cost-effective catalysts for hydrogen production in alkaline media.

A novel spectroscopic technique for studying metal-organic frameworks based on Mie scattering.

Metal-organic frameworks (MOFs) are promising candidates for a wide range of applications, and spectroscopic techniques are important tools for analyzing their structures and properties. Here, we propose a novel and general scattering spectroscopic approach to study various MOFs such as zeolitic imidazolate frameworks (ZIF-67 and ZIF-8), HKUST-1, Co-based MOF (Co-MOF), and Ni-based MOF (Ni-MOF) based on their inherent Mie scattering properties. We show that by using a dark-field microscope, the inherent scattering colors and spectra can be obtained, which are mainly from the high-order magnetic and electric resonant modes. The scattering capacities are dependent on the chemical structures for producing polarized charges and internal circular displacement currents. Additionally, all the MOFs are capable of responding to solvent guests due to their high porosity, and the scattering peaks are in a linear correlation with solvent refractive indices, displaying scattering solvatochromic behaviors. Our results open up a powerful and universal avenue for visually studying the host-guest interactions in MOFs.

Reticular Coordination Induced Interfacial Interstitial Carbon Atoms on Ni Nanocatalysts for Highly Selective Hydrogenation of Bio-Based Furfural under Facile Conditions.

A rational design of transition metal catalysts to achieve selective hydrogenation of furfural (FFR) to tetrahydrofurfuryl alcohol (THFA) under facile conditions is a promising option. In this work, a series of Ni catalysts were synthesized by controlled thermal treatment of Ni-based metal-organic frameworks (MOFs), with the purpose of modulating the interface of nickel nanoparticles by the reticular coordination in MOF precursors. The catalytic performance indicates that Ni/C catalyst obtained at 400 °C exhibits efficient conversion of FFR (>99%) and high selectivity to THFA (96.1%), under facile conditions (80 °C, 3 MPa H2, 4.0 h). The decomposition of MOF at low temperatures results in highly dispersed Ni0 particles and interfacial charge transfer from metal to interstitial carbon atoms induced by coordination in MOF. The electron-deficient Ni species on the Ni surface results in an electropositive surface of Ni nanoparticles in Ni/C-400, which ameliorates furfural adsorption and enhances the hydrogen heterolysis process, finally achieving facile hydrogenation of FFR to THFA.

Regulating Exposed Facets of Metal-Organic Frameworks for High-rate Alkaline Aqueous Zinc Batteries.

Metal-organic frameworks (MOFs) have drawn growing attention as promising electrode candidates for rechargeable batteries. However, most studies focus on the direct use of MOF electrodes without any modification. Post-synthetic modification, a judicious tool to modify targeted properties of MOFs, has been long-neglected in the field of batteries. Herein, crystal-facet engineering is proposed to design MOF-based electrodes with high capacity and fast electrochemical kinetics. We found that a thermally-modified strategy can regulate the dominant exposed facet of Ni-based MOF (PFC-8). With the optimally exposed facets, the battery exhibited admirable rate capability (139.4 mAh g-1 at 2.5 A g-1 and 110.0 mAh g-1 at 30 A g-1 ) and long-term stability. Furthermore, density functional theory calculations demonstrate that stronger OH- adsorption behaviors and optimized electronic structures induced by the regulated exposed facets boost the electrochemical performance.

Photoinduced acceleration of Fe3+/Fe2+ cycle in heterogeneous FeNi-MOFs to boost peroxodisulfate activation for organic pollutant degradation

The sluggish regeneration rate of Fe2+ in Fe-based heterogeneous catalysts restricts their wider application in persulfate-based advanced oxidation process (PS-AOPs). To conquer such challenge, Fe-embedded Ni-based metal-organic frameworks (FeNi-MOFs) with heteroatomic metal nodes were prepared and employed for persulfate activation to construct highly efficient PS-AOPs. Spectral analyses and density functional theory (DFT) calculations elucidated that the ligand-to-metal charge transfer and polarization of adjacent Ni centers endowed accelerated Fe3+/Fe2+ redox cycle in the resultant FeNi-MOFs under light irradiation and thus promoted the Fe2+ recovery with Fe3+/Fe2+ cycling efficiency > 58%. Consequently, the FeNi-MOFs delivered remarkable performance in peroxodisulfate activation and higher specific activity than that of the control Ni-MOFs/Fe3+ and state-of-the-art catalysts reported to date. This study provides new avenue of the accelerating Fe3+/Fe2+ circulation in entirely heterogeneous systems for persulfate activation and also highlights the great potential of MOFs in design of high-performance Fe-based catalysts for PS-AOPs.

Nickel and oxygen-containing functional groups co-decorated graphene-like shells as catalytic sites with excellent selective hydrogenation activity and robust stability

Encapsulation of metal nanoparticles is one of the promising strategies to overcome the instability of supported metal catalysts. However, improving the hydrogenation activity of multilayer graphene-like encapsulationremains a critical challenge. To address this issue, multilayer graphene-like shells (MGSs) doped with oxygen-containing functional groups (OFGs) encapsulated Ni nanoparticles catalysts (Ni@OC) were synthesized via calcining the calcination of Ni-based metal-organic framework. The Ni@OC catalysts exhibited 100 % nitroaromatics conversion, excellent product selectivity, and superior stability in harsh conditions. Experimental results indicate that the dissociation of H2 and the activation of nitrobenzene compounds can be achieved with the OFGs doped MGSs as the catalytic site in Ni@OC catalysts. In addition, OFGs promote the electron transfer from Ni core to graphene-like shells and result in structural defects of the MGSs to adsorb hydrogenation substrates. Thus, a reasonable design concept was provided to improve the hydrogenation activity of MGSs encapsulated catalysts with the stable existence of metal.

Amino-Functionalized Microporous MOFs for Capturing Greenhouse Gases CF4 and NF3 with Record Selectivity

The capture and separation of fluorinated gases (F-gases) from N2 has the potential to not only reduce greenhouse gas emissions but also provide economic benefits for the semiconductor industry. In this work, two Ni-based metal-organic frameworks (MOFs), Ni-MOF (Ni(ina)2, ina = isonicotinic acid) and amine-functionalized NH2-Ni-MOF (Ni(3-ain)2, 3-ain = 3-aminoisonicotinic acid), were constructed for capturing F-gases (CF4 and NF3). At ambient conditions, both materials exhibit very high CF4 sorption capacities (2.92 mmol g-1 for Ni-MOF and 2.69 mmol g-1 for NH2-Ni-MOF). In addition, NH2-Ni-MOF exhibited a record selectivity of 46.3 for the CF4/N2 mixture at 298 K and 100 kPa, surpassing all benchmark adsorbents, including Ni-MOF (34.7). The kinetic adsorption tests demonstrated that Ni-MOF and NH2-Ni-MOF performed well for CF4/N2 and NF3/N2 mixtures. According to grand canonical Monte Carlo (GCMC) simulations, CF4 or NF3 interacts with NH2-Ni-MOF by multiple van der Waals interactions, resulting in stronger interaction than N2. More importantly, dynamic breakthrough experiments verified the practical separation potential of the two materials for CF4/N2 and NF3/N2 mixtures.

In-situ growth of NiAl layered double hydroxides on Ni-based metal-organic framework derived hierarchical carbon as high performance material for Zn-ion batteries

The development of advanced active materials with high capacity, low-cost, and safety has become a requirement to meet future energy storage systems for electric vehicles. Herein, we report a rational in-situ synthesis of NiAl layered double hydroxides (LDHs) on Ni-based metal-organic framework (MOF)-derived porous carbons (PCs) material (NiAl-LDH/Ni@C) with cross-linking nanosheet structure and high electrical conductivity by a hydrothermal method. This unique structure design improves electrical conductivity, reduces internal resistance, and enables more electrochemically active sites to participate in chemical reactions through the strong interaction and synergy between the hierarchical structure of two-dimensional nanosheets and PCs. The results exhibit that NiAl-LDH/Ni@C composite possesses a large specific capacity (391.7 mAh g−1), high rate capability, and outstanding capacity retention stability (97.6%@10 A g−1 after 10,000 cycles). Furthermore, the as-assembled Zn-ion battery based on a NiAl-LDH/Ni@C cathode displays a remarkable capacity (345 mAh g−1@1 A g−1), excellent energy/power density (604.6 Wh kg−1/1.77 kW kg−1), and superb cycle durability (95.3%@2 A g−1). The proposed approach provides an unprecedented direction for designing advanced energy storage devices with high electrochemical performance.

Carboxyferrocene modulated Ni/Co bimetallic metal-organic framework for highly efficient electrocatalysis of urea oxidation reaction

Metal-organic frameworks (MOFs) have shown unique advantages and huge potential in heterogeneous catalysis such as photocatalysis due to their impressive physicochemical properties. However, the direct application in electrocatalysis are usually limited by their poor electrocatalysis performance. Herein, we present the synthesis of Ni/Co bimetallic organic framework with missing linkers of carboxyferrocene (NiCoMOF-Fc) on nickel foam (NF) by a facile protocol of one-step solvothermal method for the urea oxidation reaction (UOR) electrocatalysis. The integration of defect tailoring and bimetallic coupling effect changes the coordination environment of Ni active sites and optimizes the electronic structure, which significantly improves the electrocatalytic activity of the Ni-based MOF. The NiCoMOF-Fc modified NF exhibits excellent electrocatalytic performance towards UOR with high current density at low potential (140 mA cm−2 at 1.299 V vs. RHE and 782 mA cm−2 at 1.5 V vs. RHE), a small Tafel slope of 46.2 mV dec−1 and good durability. In addition, a two-electrode electrolyser with NiCoMOF-Fc as the bifunctional catalyst for UOR and hydrogen evolution reaction (HER) has also been successfully constructed, which shows bright prospect of practical use.

Stable Nickel-Based Metal–Organic Framework Containing Thiophene/Diimidazole Units for Effective Near-Infrared Photothermal Conversion

Herein, a new Ni-based metal–organic framework (MOF, 1) bearing highly structural stability is synthesized by the reaction of utilizing a rigid and functionalized linker, 2,6-bis(pyridin-4-yl)-1,7-dihydrobenzo[1,2-d:4,5-d′]diimidazole (BBI4PY), in combination with Ni(NO3)2·6H2O and dibenzo[b,d]thiophene-3,7-dicarboxylic acid 5,5-dioxide (L1) under solvothermal conditions. The crystal structure of complex 1 is determined by single-crystal X-ray diffraction and is demonstrated to be a two-dimensional layered structure. In addition, PXRD, IR, TGA and UV/Vis-NIR spectra are also tested carefully to explore the solid structure of this complex. Remarkably, although no significant accumulation effect could be observed between the two-dimensional layers, a stacking interaction between DMF solvent molecules and ligand L1 could be found, which might promote non-radiative transitions and trigger obvious near-infrared photothermal conversion. Under 660 nm laser (0.6 W cm−2) illumination, the temperature of complex 1 increased rapidly from room temperature to 45.2 °C, with good thermal stability and cycle durability. Its photothermal conversion efficiency could reach 10.75%. This work provides an efficient way for assessing the promise of materials in the field of photothermal therapy.

In Situ Synthesis of MOF‐74 Family for High Areal Energy Density of Aqueous Nickel–Zinc Batteries

Limited by single metal active sites and low electrical conductivity, designing nickel-based metal-organic framework (MOF) materials with high capacity and high energy density remains a challenge. Herein, a series of bi/multimetallic MOF-74 family materials in situ grown on carbon cloth (CC) by doping Mx+ ions in Ni-MOF-74 is fabricated: NiM-MOF@CC (M = Mn2+ , Co2+ , Cu2+ , Zn2+ , Al3+ , Fe3+ ), and NiCoM-MOF@CC (M = Mn2+ , Zn2+ , Al3+ , Fe3+ ). The type and ratio of doping metal ions can be adjusted while the original topology is preserved. Different metal ions are confirmed by X-ray absorption fine structure (XAFS). Furthermore, these Ni-based MOF electrodes are directly utilized as cathodes for aqueous nickel-zinc batteries (NZBs). Among all the as-prepared electrodes, NiCo-MOF@CC-3 (NCM@CC-3), with an optimized Co/Ni ratio of 1:1, exhibits the best electrical conductivity, which is according to the density functional theory (DFT) theoretical calculations. The NCM@CC-3//Zn@CC battery achieves a high specific capacity of 1.77 mAh cm-2 , a high areal energy density of 2.97 mWh cm-2 , and high cycling stability of 83% capacity retention rate after 6000 cycles. The synthetic strategy based on the coordination effect of metal ions and the concept of binder-free electrodes provide a new direction for the synthesis of high-performance materials in the energy-storage field.

Potential Applications of Nickel-Based Metal-Organic Frameworks and their Derivatives.

Metal-Organic Frameworks (MOFs), a novel class of porous extended crystalline structures, are favored in different fields of heterogeneous catalysis, CO2 separation and conversion, and energy storage (supercapacitors) due to their convenience of synthesis, structural tailor-ability, tunable pore size, high porosity, large specific surface area, devisable structures, and adjustable compositions. Nickel (Ni) is a ubiquitous element extensively applied in various fields of catalysis and energy storage due to its low cost, high abundance, thermal and chemical stability, and environmentally benign nature. Ni-based MOFs and their derivatives provide us with the opportunity to modify different properties of the Ni center to improve their potential as heterogeneous catalysts or energy storage materials. The recent achievements of Ni-MOFs and their derivatives as catalysts, membrane materials for CO2 separation and conversion, electrode materials and their respective performance have been discussed in this review.

The nickel phosphate rods derived from Ni-MOF with enhanced electrochemical activity for non-enzymatic glucose sensing

In this work, spherical Ni-based metal-organic frameworks (Ni-MOFs) were used as precursors for preparing nanorod-like nickel phosphate (r-NiPO) with enhanced electro-catalytic properties in detection of glucose. It was found that the addition of nickel ion has a profound effect on construction of nickel phosphate with flower-like, rod-like, and ribbon-like structure in presence of H2PO2−. The r-NiPO consisted of multiple phases of nickel phosphate showed porous, interconnected structure and abundant active Ni(II)/Ni(III) pairs, which was beneficial to facilitate glucose oxidation. In comparison with Ni-MOF, r-NiPO exhibited the superior electrocatalytic property on oxidation of glucose because of the exposing more active Ni sites in r-NiPO than that of Ni-MOF precursor. r-NiPO modified glassy carbon electrode (r-NiPO/GCE) showed a good linear response to glucose from 1.0 μM to 3.0 mM with a high sensitivity of 3169 μA mM−1 cm−2. In addition, r-NiPO/GCE can be used to detect glucose in human serum with satisfactory recoveries (90–97%).

MOF-derived NiSe2 nanoparticles grown on carbon fiber as a binder-free and efficient catalyst for hydrogen evolution reaction

It is challenging to grow inexpensive cathode material with superior catalytic properties for hydrogen evolution reaction (HER). Metal-organic frameworks (MOFs) have emerged as powerful platforms to synthesize efficient and ultrastable catalysts for hydrogen production. In this research, NiSe2 nanoparticles were derived from Ni-based MOF, which grown in situ on carbon fiber (NiSe2/C/CF) through pyrolysis and selenization processes. NiSe2/C/CF displays a higher HER performance than that of Ni/C/CF and Ni-MOF-74/CF. Notably, the NiSe2/C/CF electrode gives a low overpotential of 209 mV, a Tafel slope of 74.1 mV/dec, and outstanding stability with slight decay after operating for 12 h. The high HER catalytic activity of NiSe2/C/CF is mainly ascribed to the emerging effects of NiSe2 nanoparticles and three-dimensional conductive substrate CF, facilitating active moieties exposure and electron transfer during the electrocatalytic process. Therefore, this work illustrates a novel approach for the preparation of transition metal chalcogenides as low-cost and stable catalysts for HER.