Ni Metal-organic Frameworks Research Articles

Heterostructured Nanocomposites of NiCo–S@Ni(OH)2 on Ni Foam for High-Performance Supercapacitors

The development of composite materials is a key area of research for enhancing the electrochemical performance of electrode materials. In this study, NiCo–S nanostructured hybrid electrode materials were prepared on nickel foam (NF) by using binary metal–organic frameworks (MOFs) as the sacrificial template through a two-step hydrothermal method. Ni–MOF was then deposited on the surface of NiCo–S/NF through the hydrothermal method and subsequently converted into Ni(OH)2 through a subsequent alkalization treatment. The duration of the Ni–MOF hydrothermal process was varied as a parameter. NiCo–S@Ni–MOF/NF was prepared through hydrothermal reaction for 6[Formula: see text]h, 9[Formula: see text]h and 12[Formula: see text]h, followed by heating in a 6[Formula: see text]M KOH solution at 75[Formula: see text]C for 6[Formula: see text]h in a water bath. The electrode materials with the best morphology and electrochemical properties were obtained when the hydrothermal reaction time was 6[Formula: see text]h. The optimized electrode had a specific capacity of 2533.2[Formula: see text]F[Formula: see text]g[Formula: see text] at 1[Formula: see text]A[Formula: see text]g[Formula: see text] and a capacity retention rate of 60.8% at 10[Formula: see text]A[Formula: see text]g[Formula: see text], which indicated good rate performance. Additionally, the electrode material demonstrated excellent cycling stability, with a capacity retention rate of 95.3% after 5000 cycles at 50[Formula: see text]mV[Formula: see text]s[Formula: see text]. The energy density of the hybrid supercapacitor device assembled from this electrode material was 33.5[Formula: see text]Wh[Formula: see text]kg[Formula: see text] when the power density was 849.89[Formula: see text]W[Formula: see text]kg[Formula: see text] at a current density of 1[Formula: see text]A[Formula: see text]g[Formula: see text].

Dual-metal-based (Mo, Ni) MOFs nanoplates for enhanced corrosion resistance and frictional resistance of epoxy resin on magnesium alloy surfaces

Magnesium alloys face severe corrosion issues due to their high electrochemical activity. In recent years, polymer coatings containing metal-organic frameworks (MOFs) have shown great potential in improving the corrosion resistance of metals. In this study, nickel salts and molybdate were used as metal sources, and 4,4′-bipyridine was used as the organic ligand. For the first time, a nickel and molybdenum-based metal-organic framework (Mo-Ni-MOF) was synthesized via hydrothermal method. Mo-Ni-MOFs were then incorporated as nanofillers into epoxy resin and coated on AK61M magnesium alloy to enhance its long-term corrosion resistance. Characterization tests including FT-IR, FE-SEM, EDX, XRD and XPS confirmed the successful reaction between metal ions and organic ligands, indicating successful coordination. TEM analysis revealed that the MOFs consisted of nanosheets with diameters ranging from 20 to 100 nm. BET analysis demonstrated the porous structure of the synthesized nanoparticles, with a high specific surface area ranging from 6 to 44 m2.g−1 and an average pore size ranging from 9 to 32 nm. Salt spray tests demonstrated that MOFs synthesized under different conditions exhibited superior long-term corrosion resistance compared to pure epoxy coatings in artificial scratch coating performance. Electrochemical impedance spectroscopy (EIS) testing revealed a three-order-of-magnitude enhancement in |Z| at 0.01 Hz for the most effective MOF compared to pure epoxy resin. Tafel tests showed a significant decrease in corrosion current, with reductions of 2–3 orders of magnitude. Friction tests revealed a decrease in the coefficient of friction after the addition of MOFs, with reductions ranging from 0.1 to 0.4, indicating improved durability of the coating against friction.

Improved rate capability and energy density of high-mass hybrid supercapacitor realized through long-term cycling stability testing and selective electrode design

To render supercapacitors (SCs) more practical, they must exhibit high cycling stability of at least ten thousand cycles with commercial-level mass loadings, which differentiates them from batteries. Metal-organic framework (MOF)-based electrode materials are promising for use in energy storage systems owing to their excellent electrochemical performance. In this study, we report the electroactivities of bimetallic MOFs (Co, Ni, and Co–Ni) using a single-step, facile, and cost-effective hydro/solvothermal method. To optimize their performances, we develop a general strategy for analyzing various binder-free MOFs. Additionally, the effects of the reaction time, reaction temperature, solvents, and elements (Ni, Co, and H2BDC) on the surface morphology and electrochemical performance are investigated. Based on an analysis of the electrochemical properties of all the synthesized electrode materials, the optimal electrode delivers an ultrahigh areal capacity of 2621 µAh cm−2 (297.1 mAh g−1) at 7 mA cm−2, with a high-rate capability of 82.5 % even at 40 mA cm−2. The optimized Co–Ni MOF electrode is employed as a positive electrode to fabricate an aqueous hybrid SC (HSC) with an activated carbon-coated nickel foam electrode as a negative electrode. The as-fabricated HSC exhibits excellent electrochemical properties with exceptional cycling stability (120k cycles) and improved rate capability (60 %). Additionally, we identify factors that contribute to improved redox reactions in the Co–Ni MOF-based HSC, such as the role of Co–Ni MOFs in the redox reaction and the influences of other structural parameters on charge storage and transfer processes. Our aim is to further understand the underlying mechanisms of the improved redox reactions and thus obtain new insights into the design and optimization of Co–Ni MOF-based HSCs. Finally, the energy storage properties of the HSC are validated by using it to power different electronic devices. The promising outcomes obtained in this work can serve as a basis for the future practical implementation of high-energy-density HSCs with high mass loadings and charging rates. SynopsisTo render the practicability of hybrid supercapacitor (HSC) with enhanced energy storage properties, we investigate the electroactivities of bimetallic metal-organic frameworks (MOFs) (Co, Ni, and Co–Ni) using a single-step, facile, and cost-effective hydro/solvothermal method. To optimize their performances, a general strategy is developed for analyzing various binder-free MOFs. Additionally, the effects of the reaction time, reaction temperature, solvents, and elements (Ni, Co, and H2BDC) on the surface morphology and electrochemical performance are studied. In addition, we validate the energy storage properties of the HSC by using it to power different electronic devices. The promising outcomes obtained in this study can serve as a basis for the future practical implementation of high-energy-density HSCs with high mass loadings and charging rates.

The effect of sulfur atom on the biomedical properties of metal organic frameworks (MOF) prepared from mercaptosuccinic acid (MSA) and dimercaptosuccinic acid (DMSA) with Co(II), Ni(II), and Cu(II) ions

Metal-organic frameworks (MOFs) were prepared at room temperature using natural occurring succinic acid derivatives, mercaptosuccinic acid (MSA), and dimercaptosuccinic acid (DMSA), as organic linker with Co(II), Ni(II), and Cu(II) as metal ions. The porosity, thermal, and structural properties of MSA- and DMSA-based Co(II), Ni(II) and Cu(II) MOFs were characterized and DMSA-Cu(II) MOFs were found to have higher surface area and lower pore size values, 73.7 m2/g, and 12.7 nm, respectively. The metal ion amount in MSA and DMSA-based MOF structures via Atomic Absorption Spectroscopy (AAS) analysis revealed an increased amount of Metal ions with the increasing number of −SH groups in the MOF structures. The antioxidant activities of DMSA-based MOFs were measured higher than MSA-based MOFs by ABTS•+scavenging assay. DMSA-Cu(II) MOFs showed higher antioxidant activity with 4.58 ± 0.13 μmol trolox g−1. Both MSA- and DMSA-MOFs presented hemocompatible behavior at concentrations < 100 µg/mL. Also, against B. subtilis and S. aureus bacteria strains, DMSA-Cu(II) MOFs showed higher antimicrobial activity than all the other prepared MSA- and DMSA-based MOFs with a MIC value of 31 µg/mL and MBC value of 125 µg/mL for both bacteria strains. Moreover, the MSA- and DMSA-MOFs at 250 μg/mL concentration retain about 80 % cell viability for L929 fibroblast cells at 24 incubation time.

Optimizing electrochemical power generation: Harnessing synergies and surface innovation in NiTe-modified MOF nanoarchitectures

Metal-organic frameworks (MOFs) are considered potential electrocatalysts due to their high specific surface area (SSA) and the facilitation of efficient synergistic interactions. In this work, we have implemented a simple and cost-effective surface modification approach to design an efficient electrocatalyst for energy-conversion technologies, specifically water splitting. This work focuses on engineering a novel NiTe functionalized MOF structure wherein NiTe within the MOF channels is the core material, intricately intertwined with highly dispersed Ni particles enveloped by Ni MOF. This fusion of MOFs and NiTe within a designed configuration produces an efficient electrocatalyst with synergistic and surface interface effects and demonstrates bifunctional activity for water splitting. Among the prepared catalysts, one of the resulting catalysts (named Ni MOF/Ni/Ni10Te8) exhibits a low overpotential of 99 mV for the hydrogen evolution reaction (HER) and 180 mV for the oxygen evolution reaction (OER), both benchmarked against RHE @10 mA cm−2. This performance remains steady, with a stability of 99 % after 15 h of continuous operation. Furthermore, the Ni MOF/Ni/Ni10Te8 catalyst also operates in seawater electrocatalysis, requiring a low overpotential of 440 mV at 10 mA cm−2 to produce 70 mL of hydrogen and 34 mL of oxygen. Equally noteworthy are the Faradaic efficiencies achieved, with hydrogen production at 95.7 % and oxygen production at 92.9 %. Developing efficient and economically viable electrocatalysts like the Ni MOF/Ni/NiTe catalyst will advance a cleaner and more sustainable future.

Hierarchical heterostructure Ni2P hollow carbon spheres derived from MOFs for efficient electromagnetic wave absorption

In this study, a hierarchical heterogeneous structure of Ni2P hollow carbon spheres (Ni2P-HCS) was synthesized through a two-step process involving carbonization and phosphorization of Ni-metal organic framework (Ni-MOF) precursors. During the construction of the Ni2P/C nanostructure, heterointerface recombination and secondary graphitization were observed, which contribute to the modulation of interface polarization. Structural analysis revealed that the Ni2P/C nanoparticles are uniformly dispersed, forming stable porous structured microspheres, thereby leveraging dielectric and magnetic losses. The combination of Ni2P with metal-organic frameworks (MOFs) can optimize impedance matching, enhance effective absorption bandwidth, and consequently improve electromagnetic wave absorption performance. The results show that Ni2P-HCS (Ni2P-HCS700) exhibited superior electromagnetic wave (EMW) absorption characteristics when the carbonization temperature is 700 ℃. It achieves a maximum reflection loss (RL) of −46.7 dB at a thickness of 2.9 mm and an effective absorption bandwidth (EAB) of 4.8 GHz at 1.71 mm thickness, almost covering the Ku-band (13.3 GHz−18 GHz). Radar cross-section (RCS) simulations utilizing CST indicated an optimal RCS reduction value of 41 dB m² at theta=0° for Ni2P-HCS700. This work introduces a universal approach to designing high-performance lightweight absorbers derived from MOFs, incorporating transition metal phosphides to form composites for impedance matching control.

Construction of nickel phosphide/iron oxyhydroxide heterostructure nanoparticles for oxygen evolution

Active and stable oxygen evolution electrocatalysts are essential in increasing the efficiency of water electrolyzers. The Ni2P/Fe(O)OH heterostructure nanoparticles are prepared via solvothermal phosphidization of Ni metal-organic frameworks (MOF) followed by immersing in Fe3+ aqueous solution. Characterizations reveal that the Ni2P/Fe(O)OH heterostructure nanoparticles are 12.83 nm in size averagely, and the heterointerface induces electron interactions between the Ni2P and Fe(O)OH phases. When used to catalyze OER in alkaline solutions, the Ni2P/Fe(O)OH-40/nickel foam (NF) is the most active and exhibits 240 mV overpotential to reach 10 mA cm−2 oxygen evolution (OER) current densities, which is significantly better than the Ni2P/NF. Lower apparent activation energy, charge transfer resistance, and Tafel slope, along with higher electron rate constant are observed at Ni2P/Fe(O)OH-40/NF, which suggests that the OER kinetics is more facile at the surface of heterostructure nanoparticles. The OER mechanistic pathways of both Ni2P/Fe(O)OH-40/NF and Ni2P/NF involve decoupled electron and proton transfer processes, and higher degree of lattice oxygen oxidation mechanism (LOM) participation is observed at Ni2P/Fe(O)OH-40/NF, which results from the increased acidity of the Ni sites. Density functional theory calculations prove that the formation of heterostructure with Fe(O)OH alters the band structure and the adsorption energies of OER intermediates, which leads to lower energy barrier in the rate-determining step. The Ni2P/Fe(O)OH-40/NF is also stable towards OER in alkaline solutions.

Synergistic integration of Ni-metal organic framework/SnS2 nanocomposite and nickel foam electrode for ultrasensitive and selective electrochemical detection of albumin in simulated human blood serum

Albumin is a vital blood protein responsible for transporting metabolites and drugs throughout the body and serves as a potential biomarker for various medical conditions, including inflammatory, cardiovascular, and renal issues. This report details the fabrication of Ni-metal organic framework/SnS2 nanocomposite modified nickel foam electrochemical sensor for highly sensitive and selective non enzymatic detection of albumin in simulated human blood serum samples. Ni-metal organic framework/SnS2 nanocomposite was synthesized using solvothermal technique by combining Ni-metal–organic framework (MOF) with conductive SnS2 leading to the formation of a highly porous material with reduced toxicity and excellent electrical conductivity. Detailed surface morphology and chemical bonding of the Ni-MOF/SnS2 nanocomposite was studied using scanning electron microscopy, transmission electron microscopy, Fourier transform infra-red, and Raman analysis. The Ni-MOF/SnS2 nanocomposite coated on Ni foam electrode demonstrated outstanding electrochemical performance, with a low limit of detection (0.44 μM) and high sensitivity (1.3 μA/pM/cm2) throughout a broad linear range (100 pM–10 mM). The remarkable sensor performance is achieved through the synthesis of a Ni-MOF/SnS2 nanocomposite, enhancing electrocatalytic activity for efficient albumin redox reactions. The enhanced performance can be attributed due to the structural porosity of nickel foam and Ni-metal organic framework, which favours increased surface area for albumin interaction. The presence of SnS2 shows stability in acidic and neutral solutions due to high surface to volume ratio which in turn improves sensitivity of the sensing material. The sensor exhibited commendable selectivity, maintaining its performance even when exposed to potential interfering substances like glucose, ascorbic acid, K+, Na+, uric acid, and urea. The sensor effectively demonstrates its accuracy in detecting albumin in real samples, showcasing substantial recovery percentages of 105.1%, 110.28%, and 91.16%.

Two-Dimensional Nickel Porphyrinic Metal-Organic Framework-Modified Electrode for Electrochemical Sensing.

Due to their highly exposed active sites and high aspect ratio caused by their substantial lateral dimension and thin thickness, two-dimensional (2D) metal-organic framework (MOF) nanosheets are currently considered a potential hybrid material for electrochemical sensing. Herein, we present a nickel-based porphyrinic MOF nanosheet as a versatile and robust platform with an enhanced electrochemical detection performance. It is important to note that the nickel porphyrin ligand reacted with Cu(NO3)2·3H2O in a solvothermal process, with polyvinylpyrrolidone (PVP) acting as the surfactant to control the anisotropic development of creating a 2D Cu-TCPP(Ni) MOF nanosheet structure. To realize the exceptional selectivity, sensitivity, and stability of the synthesized 2D Cu-TCPP(Ni) MOF nanosheet, a laser-induced graphene electrode was modified with the MOF nanosheet and employed as a sensor for the detection of p-nitrophenol (p-NP). With a detection range of 0.5-200 μM for differential pulse voltammetry (DPV) and 0.9-300 μM for cyclic voltammetry (CV), the proposed sensor demonstrated enhanced electrochemical performance, with the limit of detection (LOD) for DPV and CV as 0.1 and 0.3 μM, respectively. The outstanding outcome of the sensor is attributed to the 2D Cu-TCPP(Ni) MOF nanosheet's substantial active surface area, innate catalytic activity, and superior adsorption capacity. Furthermore, it is anticipated that the proposed electrode sensor will make it possible to create high-performance electrochemical sensors for environmental point-of-care testing since it successfully detected p-NP in real sample analysis.

Electrochemical performance of M(dca)2pyz (M = Fe, Co and Ni) MOFs as sustainable anodes in lithium-ion batteries

A family of Metal–Organic Frameworks (MOFs) based on the ligands pyrazine (pyz) and dicyanamide (dca) and the metal centers Fe, Co and Ni with the unit formula M(dca)2pyz has been studied as anodes for Li-Ion Batteries (LIBs).

Copper-based bimetallic metal–organic framework in-situ embedded of heterogeneous Cu nanoparticles for enhanced nonenzymatic glucose sensing

Copper-based metal–organic frameworks (MOFs) are recently emerging as encouraging electrocatalysts with high performance and stability for electrochemical detection of glucose. Herein, a simple one-step solvothermal in-situ derivative strategy is proposed to fabricate the novel heterogeneous electrocatalyst of Cu nanoparticles embedded bimetallic Cu@MCu-BDC-NH2 (M = Ni, Co and Zn) MOFs, which can enhance the conductivity via tailor the electronic structure and heterojunction interface. The optimal bimetallic Cu@CoCu-BDC-NH2 heterostructure exposes more active sites, the electronic interaction between metal-O enhanced the reactivity and electrical conductivity, and prominently boost the kinetics of glucose detection. The optimized Cu@CoCu-BDC-NH2 heterojunction structure as modified electrode nanomaterials exhibit the low detection limit (0.27 μM), wide linear range (0.5 μM–2 mM) and the high sensitivity (21157 μA mM−1 cm−2), which are successfully used in human serum and hold great stability and anti-interference. The density functional theory (DFT) calculation demonstrates that the adsorption energies of Cu@CoCu-BDC-NH2 heterostructure for glucose are −0.3 eV, suggesting good adsorption capacity for glucose. This work not only successfully establish Cu nanoparticles heterostructure interface with bimetallic MOFs for high-performance glucose sensors, but also emphasizes the importance of regulate the electronic microstructure of bimetallic MOFs for enhanced reaction kinetics.

Ni-MOF Based Flexible Solid-State Supercapacitors in Aqueous and Non-Aqueous Electrolytes

Supercapacitors are high power density devices which acts a bridge between the batteries and conventional capacitors. Several emerging materials like Metal Organic Frameworks (MOFs) have been developed as electrode material for energy storage. MOFs are highly porous materials containing metal centers and organic moieties called ligands [1].They are widely employed for energy storage applications owing to their structural and morphological tunability [2]. In our recent research work, Ni MOF is synthesized using microwave assisted solvothermal technique at different temperature and metal to ligand ratios. Ni MOF is synthesized by varying metal to ligand ratio (M:L) as 1:1, 2:1, 3:1 and 4:1. The solution is heated by microwave irradiation technique [3] from room temperature to 150, 165, 180 and 200 °C to obtain light green colored samples. It is interesting to observe that different synthesis parameters lead to different morphologies thereby resulting in improved performance of Ni MOF. The structural and electrochemical characterizations reveal “why does a particular morphology exhibits better charge storage capacity?” The three electrode configuration experiments were conducted in aqueous electrolyte to evaluate the charge storage capacity. The results show that globules (∼1360 F g-1) perform better than nanoflower (∼850 F g-1), flakes (∼650 F g-1) and plates (∼450 F g-1) [4] respectively in 2M KOH at 0.5 A g-1. The reason is attributed to the low solution resistance (R sol) for globules, reduced charge transfer resistance (R ct) and the global and local n values of CPE.The synthesized material (Ni MOF) will be used as positive electrode material for flexible asymmetric supercapacitor. Recently, flexible state supercapacitors (FSSCs) have gained popularity due to their formability, flexibility and high energy density. Here, the objective is to increase energy density and power density by extending the operating potential window of the device. Hence, the aqueous electrolyte is substituted with PVDF based ionogels (ionic liquid gel polymer) to impart flexibility, bendability and high power density to FSSC. It is observed that the potential window improved remarkably from ~0.6 V (aqueous electrolytes) to ~5 V (ionic liquid). The reason is attributed to the absence of water, results in thermodynamic stability of the electrolyte. Also, the ionic liquid based FSSCs are non-flammable, non-toxic, thermally stable. In order to improve the conductivity and charge storage capacity some additives are incorporated in the gel polymer matrix. Herein, certain polar solvents are added to enhance the conductivity due to their high dielectric constant giving rise to faster ionic dissociation. MOF based flexible supercapacitors are fabricated and tested for their energy and power densities in conjunction with electrochemical and structural characteristics .

Enhanced thermal storage and photo-thermal conversion composite phase change materials based on MOF-derived carbon for efficient solar energy utilization

Composite phase change materials (PCMs) with high thermal conductivity and photo-thermal conversion performance can be employed for the efficient conversion and utilization of solar energy. In this work, a Ni-doped carbon material derived from a Ni metal-organic framework (Ni-BTC) is prepared and used as the supporting material to encapsulate polyethylene glycol (PEG). The Ni-BTC derived carbon (NBC) obtained retained the intrinsic porous flower-like structure which facilitates the encapsulation of PEG. The doping of Ni metal particles enhances both the thermal conductivity and photo-thermal conversion performance of the composite PCM. Additionally, the thermal conductivity of the composite PCM is further enhanced by the addition of a graphene/Ag composite, resulting in a thermal conductivity that is 3.15 times higher than that of pure PEG. The latent heat of the resulting composite PCM is 125.4 J/g, the photo-thermal conversion efficiency is 91.81 %. Moreover, the composite PCM exhibits excellent thermal stability and reliability, indicating its potential for wide-ranging applications in solar energy storage.

Ruthenium-nickel oxide derived from Ru-coupled Ni metal–organic framework for effective oxygen evolution reaction

Developing Ru-based catalysts with both high activity and stability for the oxygen evolution reaction (OER) is very significant in the water electrolysis technique. Here, a bimetallic metal oxide catalyst (RuO2-NiO) derived from Ru-coupled Ni metal–organic framework (Ni-MOF) by using terephthalic acid as the ligand was successfully synthesized through a facile ultrasonic treatment and subsequent thermal annealing approach; and the effective role of the coupled effect between RuO2 and NiO in stabilizing Ru was found significant in OER catalysis. A relatively small d-band center due to the electronic structure regulation and synergistic effect of the heterostructure was found to cause weakened adsorption of surface oxygen species. Theoretical calculations demonstrated that the electronic modulation between RuO2 and NiO can significantly accelerate the dissociation of water and modulate the chemical adsorption of oxygen intermediates on the catalyst, thereby enhancing the OER activity of the catalyst. The optimized catalyst of RuO2-NiO afforded a current density of 10 mA cm−2 at low overpotentials of 210 mV toward OER, and good catalytic stability, kinetics and efficiency were also discussed. This remarkable catalytic performance can be attributed to the unique sheet-like structure and porous morphology of the catalyst with increased exposure of active sites and the coupling effect between RuO2 and NiO for moderate binding strength to the intermediates. This study showed an effective approach for bimetallic oxide catalyst fabrication and their applications in energy conversion reactions.

Photodegradation of MC-LR using a novel Au-decorated Ni metal-organic framework (Au/Ni-MOF)

Microcystins (MCs) are toxins produced by cyanobacteria commonly found in harmful algal blooms (HAB) occurring in many surface waters. Conventional methods for removing MC-LR such as membrane filtration and activated carbon are only phase change removal methods and are often expensive in operation and maintenance. It is urgent to develop a rapid, easy-to-use, and cost-effective method for the degradation of MC-LR. In this study, a novel Au-decorated Ni-metal-organic framework (Au/Ni-MOF) was newly developed on a hydrophilic carbon fiber paper (2 cm × 2 cm) using an air spraying method. The Au/Ni-MOF was then applied for the photodegradation of MC-LR in water under UV–Vis. The addition of Au onto the surface of the Ni-MOF resulted in a nearly fivefold enhancement in the reaction rate coefficient (k), reaching a value of 0.0599 min−1 for the photodegradation of MC-LR (initial concentration of 20 ppb). It was found that 94.2% of MC-LR removal was attributed to photodegradation, with the remaining 5.8% from adsorption. The rate coefficient of 20 ppb of MC-LR in the surface water sample (pH 6.0) was 0.06 min−1 likely due to the presence of other contaminates including scavenger agents within the sample which inhibits the degradation reaction of the MC-LR. Overall, this study demonstrated the potential for the novel Au/Ni-MOF to effectively reduce the concentration of the MC-LR toxin in the contaminated water.

MOF-derived Ni3S2@C grown in situ on modified cotton textile as self-standing electrodes towards high performance sodium ion batteries

Textile-based electrodes play an important role in realizing the application of wearable electronics. Nevertheless, weak interaction between active material and textile substrate and the volume expansion of nickel sulfides severely restrict the sodium storage performance. Herein, Ni-metal organic frameworks (Ni-MOF) as precursor are in situ grown on three-dimensional porous cotton textile substrate, followed by solution-phase stirring/hydrothermal reaction and pyrolysis, resulting in carbonized cotton textile (CC)/Ni3S2@SC and CC/Ni3S2@HC. Especially, CC/Ni3S2@HC composites present small nanoparticles, high conductivity, facilitated ion diffusion, and structural integrity, enabling excellent rate capabilities and long cycling stability. As anodes for sodium ion batteries, CC/Ni3S2@HC-700 electrode yields 268.2 and 140.6 mAh g−1 after 100 and 1000 cycles at the current density of 0.1 and 1 A g−1, respectively. Moreover, kinetic analysis shows that advantageous surface pseudocapacitive behavior of the CC/Ni3S2@HC-700 composites reaches 75 % at the scan rate of 2 mV s−1. The reported method is versatile and can be extended to fabricate other textile-based transition-metal sulfides.

Accelerated Oxygen Evolution Kinetics by Engineering Heterojunction Coupling of Amorphous NiFe Hydr(oxy)oxide Nanosheet Arrays on Self-Supporting Ni-MOFs.

Designing definite transition metal heterointerfaces is considered an effective strategy for the construction of efficient and robust oxygen evolution reaction (OER) electrocatalysts, but rather challenging. Herein, amorphous NiFe hydr(oxy)oxide nanosheet arrays (A-NiFe HNSAs) are grown in situ on the surface of a self-supporting Ni metal-organic frameworks (SNMs) electrode via a combination strategy of ion exchange and hydrolytic co-deposition for efficient and stable large-current-density water oxidation. The existence of the abundant metal-oxygen bonds on the heterointerfaces can not only be of great significance to alter the electronic structure and accelerate the reaction kinetics, but also enable the redistribution of Ni/Fe charge density to effectively control the adsorption behavior of important intermediates with a close to the optimal d-band center, dramatically narrowing the energy barriers of the OER rate-limiting steps. By optimizing the electrode structure, the A-NiFe HNSAs/SNMs-NF exhibits outstanding OER performance with small overpotentials of 223 and 251mV at 100 and 500mA cm-2 , a low Tafel slope of 36.3mV dec-1 , and excellent durability during 120h at 10mA cm-2 . This work significantly provides an avenue to understand and realize rationally designed heterointerface structures toward effective oxygen evolution in water-splitting applications.

Metal-organic framework-mediated construction of confined ultrafine nickel phosphide immobilized in reduced graphene oxide with excellent cycle stability for asymmetric supercapacitors

Transition metal phosphides (TMPs) with unique metalloid features have been promised great application potential in developing high-efficiency electrode materials for electrochemical energy storage. Nevertheless, sluggish ion transportation and poor cycling stability are the critical hurdles limiting their application prospects. Herein, we presented the metal-organic framework-mediated construction of ultrafine Ni2P immobilized in reduced graphene oxide (rGO). Nano-porous two-dimensional (2D) Ni-metal-organic framework (Ni-MOF) was grown on holey graphene oxide (Ni(BDC)-HGO), followed by MOF-mediated tandem pyrolysis (carbonization and phosphidation; Ni(BDC)-HGO-X-P, X denoted carbonization temperature and P represented phosphidation). Structural analysis revealed that the open-framework structure in Ni(BDC)-HGO-X-Ps had endowed them with excellent ion conductivity. The Ni2P wrapped by carbon shells and the PO bonds linking between Ni2P and rGO ensured the better structural stability of Ni(BDC)-HGO-X-Ps. The resulting Ni(BDC)-HGO-400-P delivered a capacitance of 2333.3 F g−1 at 1 A g−1 in a 6 M KOH aqueous electrolyte. More importantly, Ni(BDC)-HGO-400-P//activated carbon, the assembled asymmetric supercapacitor with an energy density of 64.5 Wh kg−1 and a power density of 31.7 kW kg−1, almost maintained its initial capacitance after 10,000 cycles. Furthermore, in situ electrochemical-Raman measurements were exploited to demonstrate the electrochemical changes of Ni(BDC)-HGO-400-P throughout the charging and discharging processes. This study has further shed light on the design rationality of TMPs for optimizing supercapacitor performance.

From 1D to 2D: Controllable Preparation of 2D Ni-MOFs for Supercapacitors.

Controllable modulation strategies between one-dimensional (1D) and two-dimensional (2D) structures have been rarely reported for metal-organic frameworks (MOFs). Here, 1D, 1D/2D, and 2D Ni-MOFs can be facilely prepared by adjusting the ratio of Ni2+ and the pyromellitic acid linker. A low-dimensional structure can shorten the transmission distance, while MOFs with a high Ni2+ content can supply rich active sites for oxidation-reduction reactions. The 2D structure Ni-MOF with an optimized Ni2+/pyromellitic acid ratio presents a good performance of 1036 F g-1 at a current density of 1 A g-1 with a comparable rate performance of 62% at 20 A g-1. The study may offer a facile design to control the structure of MOFs for employing in electrochemical energy storage.

Metal organic frameworks derived NiSe2 microspheres wrapped with graphene as a high-performance cathode for rechargeable magnesium batteries

Rechargeable magnesium batteries (RMBs) are suitable for large-scale energy storage, but the cathode materials are deficient. Herein, NiSe2 microspheres derived from Ni-metal organic frameworks (Ni-MOFs) and wrapped with reduced graphene oxide (NiSe2/rGO) are fabricated and used as RMB cathodes. The NiSe2 microspheres are composed of tiny nanoparticles and interweaved with conductive graphene network. The NiSe2/rGO cathode exhibits a capacity of 215.5 mAh g−1 at 50 mA g−1, a good rate capability of 66.8 mAh g−1 at 2.0 A g−1 and a stable cycling for 300 cycles. Further kinetic investigation indicates the graphene improves the activity of the tiny NiSe2 nanoparticles, enhancing the interphase charge transfer and the magnesium storage performance.