Nickel-based Metal-organic Framework Research Articles

A Dual-Responsive Magnetoactive and Electro-Ionic Soft Actuator Derived from a Nickel-Based Metal-Organic Framework.

There is growing demand for multiresponsive soft actuators for the realization of natural, safe, and complex motions in robotic interactions. In particular, soft actuators simultaneously stimulated by electrical and magnetic fields are always under development owing to their simple controllability and reliability during operation. Herein, magnetically and electrically driven dual-responsive soft actuators (MESAs) derived from novel nickel-based metal-organic frameworks (Ni-MOFs-700C), are reported. Nanoscale Ni-MOFs-700C has excellent electrochemical and magnetic properties that allow it to be used as a multifunctional material under both magnetoactive and electro-ionic actuations. The dual-responsive MESA exhibits a bending displacement of 30mm and an ultrafast rising time of 1.5 s under a very low input voltage of 1V and also exerts a bending deflection of 12.5mm at 50 mT under a high excitation frequency of 5Hz. By utilizing a dual-responsive MESA, the hovering motion of a hummingbird robot is demonstrated under magnetic and electrical stimuli.

Enhancing Electrochemiluminescence Efficiency through Introducing Atomically Dispersed Ruthenium in Nickel-Based Metal-Organic Frameworks.

The successful application of electrochemiluminescence (ECL) in various fields required continuous exploration of novel ECL signal emitters. In this work, we have proposed a pristine ECL luminophor named NiRu MOFs, which owned extremely high and stable ECL transmission efficiency and was synthesized via a straightforward two-step hydrothermal pathway. The foundation framework of pure Ni-MOFs with the initial structure was layered-pillared constructed by the coordinated octahedrally divalent between nickel and terephthalic acid (BDC). The terephthalates were coordinated and pillared directly to the nickel hydroxide layers and the three-dimensional framework was formed, which had a weak ECL response strength. Then, the ruthenium pyridine complex was recombined with pure Ni-MOFs to produce NiRu MOFs and part of the introduced ruthenium was atomically dispersed in the layered-pillared structure through an ion-exchange method, which led to the ECL luminous efficiency being significantly boosted more than pure Ni-MOFs. In order to verify the superiority of this newly synthesized illuminant, an ECL immunoassay model has been designed, and the results demonstrated that it had extremely strong and steady signal output in practical application. This study realized an efficient platform in ECL immunoassay application with the limit of detection of 0.32 pg mL-1 for neuron-specific enolase (NSE). Therefore, the approach which combined the pristine pure Ni-MOFs and the star-illuminant ruthenium pyridine complex would provide a convenient and meaningful solution for exploring the next-generation ECL emitters.

Hydrothermal synthesis of Ni(II) or Co(II)-based MOF for electrocatalytic hydrogen evolution

Electrocatalytic hydrogen evolution reactions (HER) can produce clean hydrogen energy. Precious metal electrocatalysts had excellent electrocatalytic activity. However, its limited resources and high price limited its large-scale application. Therefore, the design of efficient, stable and low-cost non-precious metal electrocatalysts has become the key to improving HER efficiency. Herein, we synthesized two cobalt and nickel-based Metal-Organic Frameworks (MOFs), [Ni(bib)2(SO4)]n (Ni-MOF) and [Co(bib)2(SO4)]n (Co-MOF) using bib as a ligand (bib = 1,4-bis(1-imidazolyl)benzene). Ni-MOF-T or Co-MOF-T was obtained by high-temperature calcination under the nitrogen atmosphere. Ni-MOF-800 or Co-MOF-800 exhibited high electrocatalytic hydrogen evolution activity. Besides, the electrocatalytic performance of Co-MOF@Zn-800 obtained by doping zinc ions in Co-MOF was improved.

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.

Facile Synthesis of 4,4'-biphenyl Dicarboxylic Acid-Based Nickel Metal Organic Frameworks with a Tunable Pore Size towards High-Performance Supercapacitors.

Metal-organic frameworks (MOFs) have attracted significant research interest for supercapacitor applications due to their high-tunable conductivity and their structure’s pore size. In this work, we report a facile one-step hydrothermal method to synthesize nickel-based metal-organic frameworks (MOF) using organic linker 4,4′-biphenyl dicarboxylic acid (BPDC) for high-performance supercapacitors. The pore size of the Ni-BPDC-MOF nanostructure is tuned through different synthesization temperatures. Among them, the sample synthesized at 180 °C exhibits a nanoplate morphology with a specific surface area of 311.99 m2·g−1, a pore size distribution of 1–40 nm and an average diameter of ~29.2 nm. A high specific capacitance of 488 F·g−1 has been obtained at a current density of 1.0 A·g−1 in a 3 M KOH aqueous electrolyte. The electrode shows reliable cycling stability, with 85% retention after 2000 cycles. The hydrothermal process Ni-BPDC-MOF may provide a simple and efficient method to synthesize high-performance hybrid MOF composites for future electrochemical energy storage applications.

A nickel-based metal-organic framework for efficient SF6/N2 separation with record SF6 uptake and SF6/N2 selectivity

Seeking top-performing adsorbents with salient structural stability and renewability to realize efficient adsorption and enrichment of sulfur hexafluoride (SF6) from the gaseous blend is of great importance. Here, an ultramicroporous nickel-based metal-organic framework (MOF), termed Ni(NDC)(TED)0.5 with multiple naphthalene rings-functionalized pore environment, was synthesized to efficiently separate SF6/N2 mixture. Equilibrium adsorption results show that Ni(NDC)(TED)0.5 possesses a record IAST SF6/N2 selectivity (750) and SF6 uptake (61.86 cm3 cm−3), higher than all adsorbents reported so far, and resolves the trade-off phenomenon between SF6 adsorption capacity and SF6/N2 selectivity. In particular, the selectivity is 2.3 times that of the current highest material (SBMOF-1). Furthermore, theoretical calculations reveal that the pore centers of material are the most energetically-favorable preferential adsorption sites. Meanwhile, the stronger affinity between SF6 and framework is attributed to the shorter interaction distance between F atom on SF6 and pore wall. Breakthrough tests confirm this MOF can completely separate SF6/N2 mixture. The breakthrough uptake (56.60 cm3 cm−3) and dimensionless time (τ: 281.8) of this material for SF6 are separately 1.6 and 2.5 times that of the currently reported benchmark (Cu-MOF-NH2). In combination of excellent structural stability and recyclability, this material may be an ideal material for the recovery of SF6 from SF6/N2 mixture.

Ultrathin two-dimensional nickel-organic framework nanosheets for efficient electrocatalytic urea oxidation

Synthesis of highly-efficiency electrocatalysts with controllable morphology, enriched active sites, and low cost is of great significance for urea oxidation reaction (UOR) applications. In this work, novel two-dimensional (2D) nickel-based metal-organic framework (Ni-MOF) nanosheets comprising Ni2+ and an organic ligand of 4-Dimethylaminopyridine (Ni-DMAP-t, where t is the synthesis time) are firstly synthesized by a facile one-pot solvothermal method. By thickness regulation of Ni-DMAP-t nanosheets, the self-supported Ni-DMAP-2 with the smallest thickness on Ni foam (Ni-DMAP-2/NF) exhibits high electrocatalytic activity toward UOR with a low potential of 1.45 V at a current density of 100 mA cm−2. Moreover, by further coupling with the cathodic hydrogen evolution reaction, the urea-assisted electrolytic hydrogen production system using Ni-DMAP-2/NF as anode displays a dramatic voltage reduction by 290 mV at a current density of 50 mA cm−2 as compared with that of conventional water electrolysis using the same electrodes. Such a superior UOR electrocatalytic activity of Ni-DMAP-2/NF is ascribed to the abundant Ni active sites exposed on the surface of Ni-DMAP-2, as well as the accelerated electron/ion transfer properties endowed by its ultrathin 2D nanosheets structure. This work offers some new ideas into the design and development of ultrathin 2D Ni-based MOF electrocatalysts for urea-related energy storage devices.

Turning coordination environment of 2D nickel-based metal-organic frameworks by π-conjugated molecule for enhancing glucose electrochemical sensor performance

The design and synthesis of the high-efficiency electrochemical sensor is the key to electrochemical conversion technology. This work synthesized Ni-based metal-organic framework (Ni-MOF) nanosheets by a competitive double ligands hybridization strategy. They were used as precursors to construct Ni-MOF@Ni-2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) core@shell structures by introducing π - conjugated molecule, HHTP. EXAFS further confirmed the interaction between Ni atoms and hexahydroxytriphenylene molecules. This process helps to promote more exposure of its active sites and enhance its electrochemical performance to become a high-performance enzyme glucose sensor. After coating, glucose detection sensitivity increased from 139.82 to 2124.90 μA/(mM cm2). These findings lay the foundation for preparing two-dimension hybrid functional MOF materials.

Preconcentration of Hemoglobin by a Nickel-Based Metal–Organic Framework (MOF) with Biphenyl Ligands

Adsorbents for protein enrichment underline the most important foundations in proteomic application. The construction of tunable metal-organic framework (MOF) through rational selection of metal nodes and organic linkers with designed properties has attracted special interest in the field of protein enrichment. In this work, a nickel-based MOF (NiBPDC) composed of biphenyl-based organic ligand and Ni clusters was prepared which exhibits attractive adsorption efficiency and selectivity for hemoglobin (Hb) by taking advantage of the strong metal affinity and π stacking interaction between Hb and MOF. The adsorption maximum capacity of NiBPDC for Hb is 400.2 mg g−1, and the adsorbed Hb is easily recovered by 0.5% (m/v) sodium dodecyl sulfate achieving a recovery of 98.2%. An enrichment factor up to 79.8 for Hb from an extremely 300:1 mass ratio of a human serum albumin/Hb mixture was achieved. Circular dichroism (CD) spectra reveal that the recovered Hb maintained its original structure following the enrichment. The practicability of NiBPDC is confirmed by selective enrichment of Hb from complex biological samples followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis.

Enhanced electrocatalytic performance of 2D Ni-MOF for ethanol oxidation reaction by loading carbon dots

Due to the scarcity of precious metals, it is urgently desired to develop novel non-precious metal catalysts for ethanol oxidation reactions (EOR) to improve the property of direct ethanol fuel cells (DEFCs), but it is still a huge challenge. Currently, nickel-based catalysts are known as one of the candidates to replace precious metal catalysts. Among them, nickel-based metal-organic frameworks (MOFs) have been treated as a new platform towards the development of electrocatalysts. Herein, a 2D Ni-MOF 1 was solvothermally synthesised, and combines with carbon dots (CDs) for enhancing the conductivity of MOF 1 to prepare finally MOF1-CDs@CC composites. The current density (j) of the optimal MOF1-CDs@CC toward EOR is 119 ​mA ​cm−2, which exceed those of the EOR catalysts previously reported. Meanwhile, the optimal MOF1-CDs@CC has low Tafel slope (93.9 ​mV dec−1) and high exchange j value (2.06 ​× ​10−5 ​A ​cm−2). The excellent performance of MOF1-CDs@CC is mainly ascribed to accelerating EtOH adsorption on the surface of the catalyst and charge transfer after the introduction of CDs. After 10000 ​s durability test, the retention rate of the j value of MOF1-CDs@CC is 90% of that (118 ​mA ​cm−2) of the original one, which indicates that MOF1-CDs@CC catalyst has good stability. So MOF1-CDs@CC is expected to be used as a cost-effective EOR electrocatalyst due to its simple preparation method, excellent activity and stability.

Performance investigation of adsorption cooling and desalination systems employing thermally enhanced copper foamed bed coated with SAPO-34 and CPO-27(Ni)

Despite the increasing interest in adsorption cooling and desalination systems, the poor heat hence mass transfer in the adsorbent-bed (the core component) impedes the efficient energy conversion at the system level and increases its physical footprint. In response, this paper numerically investigates the overall enhancement of adsorption cooling cum desalination system employing emerging copper foamed adsorbent beds of advanced thermal performance coated with advanced adsorbent materials to address such an untapped challenge. Silico-aluminophosphate (SAPO-34) and Nickel-based metal-organic framework CPO-27(Ni) adsorbents were employed. First, a 2-D axisymmetric computational fluid dynamic fully coupled model was developed to simulate the adsorbent-beds considering non-ideal condenser and evaporator pressures. Second, the influence of different operating conditions and copper foam thicknesses was investigated at the adsorbent-bed and system levels. The advanced adsorption kinetics of SAPO-34 enabled shortening the cycle time from 600 to 180 s, which enhanced the coefficient of performance (COP), specific cooling power (SCP), and specific daily water production (SDWP) of the system by 163%, 223%, and 228%. The regeneration temperature was the most influential parameter on the systems’ performance within the investigated range (70–100 °C). It enhanced the COP from 0.2 to 0.421, SCP from 132 to 821 W.kg−1, and SDWP from 4.7 to 29.3 m3.ton-1.day−1, for CPO-27(Ni) coated bed; and COP from 0.378 to 0.388 and SCP from 393 to 855 W.kg−1 and SDWP from 14 to 31 m3.ton-1.day−1 , for SAPO-34 coated bed. The reported enhancements at the adsorption system-level signpost metal-foamed adsorbent-bed coating the most thermally efficient adsorbent-bed design.

Preferential Adsorption Performance of Ethane in a Robust Nickel-Based Metal–Organic Framework for Separating Ethane from Ethylene

Development of an ethane-selective adsorbent to separate ethane from ethylene is a challenging issue with great significance for ethylene purification. The adsorptive separation technique based on physical adsorption holds a great promise to address this issue. Herein, we report a robust ethane-selective metal–organic framework, Ni(BODC)(TED), and investigate its separation performance on C2H6/C2H4. The as-synthesized Ni(BODC)(TED) exhibits excellent water vapor stability and high capacity of C2H6 molecules with an uptake of 3.36 mmol/g at 298 K and 100 kPa, higher than those of many adsorbents reported in recent years. Its C2H6/C2H4 selectivity predicted by the ideal adsorbed solution theory (IAST) model reaches 1.79. A molecular simulation is applied to unveil the preferential adsorption mechanism of ethane. Calculation shows that five strong C–H···H interactions are formed between C2H6 and the framework of Ni(BODC)(TED), and the isosteric heat of ethane on Ni(BODC)(TED) is 27.02 kJ/mol, higher than that of ethylene, resulting in preferential adsorption of ethane. Ni(BODC)(TED) would become a promising member of the family of ethane-selective materials for the industrial separation of ethane from ethylene.

Laser-induced sulfurization of nickel-based metal-organic frameworks for highly stable phase-engineered energy materials

Multiphase metal sulfide nanoparticles are of great importance for high-performance electrochemical energy storage devices, yet a proper synthesis method remains as elusive as ever. Here, we showed that ultra-small multiphase nickel sulfide nanoparticles embedded with conductive graphitic carbon can be easily prepared within a few minutes via laser irradiation onto a sulfur-impregnated nickel-based metal–organic framework (MOF-Ni). The phase of the resulting nickel sulfide nanoparticles (i.e., Ni3S2 and αNiS) was able to be tuned by changing the reactant ratio. We found that the carbon derived from the MOF plays a thermodynamically critical role in the formation of nickel sulfide nanoparticles. The carbon composite with 61 wt% Ni3S2 presented the highest specific capacity of up to 800 C/g and excellent cycling stability, thanks to the engineered multiphase and high porosity. Hybrid supercapacitors made of the composite showed a high energy density of 42 Wh/kg with excellent cycling stability of 96 % over 10,000 cycles. Our study demonstrated that the laser-induced sulfurization method could be an effective method to synthesize various phase-engineered metal sulfide nanoparticles supported on graphitic carbon out of numerous MOFs.

Nickel-Based Metal-Organic Frameworks for Coal-Bed Methane Purification with Record CH4 /N2 Selectivity.

The enrichment and purification of coal-bed methane provides a source of energy and helps offset global warming. In this work, we demonstrate a strategy involving the regulation of the pore size and pore chemistry to promote the separation of CH4 /N2 mixtures in four nickel-based coordination networks, named Ni(ina)2 , Ni(3-ain)2 , Ni(2-ain)2 , and Ni(pba)2 , (where ina=isonicotinic acid, 3-ain=3-aminoisonicotinic acid, 2-ain=2-aminoisonicotinic acid, and pba=4-(4-pyridyl)benzoic acid). Among them, Ni(ina)2 and Ni(3-ain)2 can effectively separate CH4 from N2 with top-performing performance because of the suitable pore size (≈0.6 and 0.5 nm) and pore environment. Explicitly, Ni(ina)2 exhibits the highest ever reported CH4 /N2 selectivity of 15.8 and excellent CH4 uptake (40.8 cm3 g-1 ) at ambient conditions, thus setting new benchmarks for all reported MOFs and traditional adsorbents. The exceptional CH4 /N2 separation performance of Ni(ina)2 is confirmed by dynamic breakthrough experiments. Under different CH4 /N2 ratios, Ni(ina)2 selectively extracts methane from the gaseous blend and produces a high purity of CH4 (99 %). Theoretical calculations and CH4 -loading single-crystal structure analysis provide critical insight into the adsorption/separation mechanism. Ni(ina)2 and Ni(3-ain)2 can form rich intermolecular interactions with methane, indicating a strong adsorption affinity between pore walls and CH4 molecules. Importantly, Ni(ina)2 has good thermal and moisture stability and can easily be scaled up at a low cost ($25 per kilogram), which will be valuable for potential industrial applications. Overall, this work provides a powerful approach for the selective adsorption of CH4 from coal-bed methane.

A portable ascorbic acid in sweat analysis system based on highly crystalline conductive nickel-based metal-organic framework (Ni-MOF)

Conductive metal–organic frameworks can provide unique porous structures, large pore volumes, many catalytically active sites and high crystallinity, and so are becoming increasingly important and attractive as electrocatalytic materials. The present work synthesized nanorods of the conductive compound Ni3(2,3,6,7,10,11-hexaiminotriphenylene)2 (Ni3(HITP)2) with a high degree of crystallinity from HITP ligands and Ni2+ ions. Screen-printed electrodes made with this material were employed to fabricate an enzyme-free sensor for the detection of ascorbic acid (AA). The sensor exhibited good catalytic activity during the electrocatalytic analysis of AA in alkaline media, attributed to the synergistic effect of highly active Ni-N4 catalytic sites in the nanorods, the two-dimensional superimposed honeycomb lattice of the Ni3(HITP)2, and the large specific surface area of this material. The latter property facilitated efficient electron transfer during catalytic oxidation. A portable electrochemical AA detection system was developed using Ni3(HITP)2 as the electrode material together with application-specific integrated circuits and a smartphone application with App. Good sensing performance was obtained, including a wide linear range (2–200 μM) with high sensitivity (0.814 μA μM−1 cm−2), and low detection limit (1 μM). This system can be used to monitor AA levels and trends in sweat to assess vitamin C intake as a part of personal health management.

Nickel-Based Metal-Organic Frameworks as Electrocatalysts for the Oxygen Evolution Reaction (OER).

The exploration of earth-abundant electrocatalysts with high performance for the oxygen evolution reaction (OER) is eminently desirable and remains a significant challenge. The composite of the metal-organic framework (MOF) Ni10Co-BTC (BTC = 1,3,5-benzenetricarboxylate) and the highly conductive carbon material ketjenblack (KB) could be easily obtained from the MOF synthesis in the presence of KB in a one-step solvothermal reaction. The composite and the pristine MOF perform better than commercially available Ni/NiO nanoparticles under the same conditions for the OER. Activation of the nickel-cobalt clusters from the MOF can be seen under the applied anodic potential, which steadily boosts the OER performance. Ni10Co-BTC and Ni10Co-BTC/KB are used as sacrificial agents and undergo structural changes during electrochemical measurements, the stabilized materials show good OER performances.

Water-Stable Nickel Metal-Organic Framework Nanobelts for Cocatalyst-Free Photocatalytic Water Splitting to Produce Hydrogen.

Development of water-stable metal-organic frameworks (MOFs) for promising visible-light-driven photocatalytic water splitting is highly desirable but still challenging. Here we report a novel p-type nickel-based MOF single crystal (Ni-TBAPy-SC) and its exfoliated nanobelts (Ni-TBAPy-NB) that can bear a wide range of pH environment in aqueous solution. Both experimental and theoretical results indicate a feasible electron transfer from the H4TBAPy ligand (light-harvesting center) to the Ni-O cluster node (catalytic center), on which water splitting to produce hydrogen can be efficiently driven free of cocatalyst. Compared to the single crystal, the exfoliated two-dimensional (2D) nanobelts show more efficient charge separation due to its shortened charge transfer distance and remarkably enhanced active surface areas, resulting in 164 times of promoted water reduction activity. The optimal H2 evolution rate on the nanobelt reaches 98 μmol h-1 (ca. 5 mmol h-1 g-1) showing benchmarked apparent quantum efficiency (AQE) of 8.0% at 420 nm among water-stable MOFs photocatalysts.

Nickel-rich layered LiNi0.8Mn0.1Co0.1O2 with dual gradients on both primary and secondary particles in lithium-ion batteries

The Li + /Ni 2+ mixing in LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) leads to fast battery capacity decay. Here we report a dual-gradient nickel-rich layered cathode material (D-NMC811), using nickel-based metal organic framework of Ni-MOF-74. The formation of a protective layer with rock salt phase due to the reduced nickel oxidation state on the surface of the primary particles resists internal strain and suppresses further phase transition, thus alleviating crack generation. After 300 cycles at ⅓ C, a high half-cell capacity retention of 88.50% with 0.038% decay per cycle is observed. The full-cell battery displays a high capacity retention of >86.7% with a Coulombic efficiency of >99.86% at ⅓ C after 300 cycles. The 300 mAh pouch cell delivers an energy density of 216.4 Wh/kg. After 500 cycles at 1.0 C, it still displays 84.1% capacity retention while the battery with conventional NMC811 only shows a retention of 53.0% after 400 cycles. • Nickel-rich layered NMC material formed with MOF • Dual element concentration gradient on both primary and secondary particles • Enhanced structure stability through thin rock salt layer on surface • Improved battery capacity retention and cyclability Shang et al. report a nickel-rich cathode material with dual concentration gradients on both primary and secondary particles. The improved structure reliability of D-NMC811 during long cycling makes it promising for applications in high energy-density lithium ion batteries.

Development of an electrochemical aptasensor based on Au nanoparticles decorated on metal-organic framework nanosheets and p-biphenol electroactive label for the measurement of aflatoxin B1 in a rice flour sample.

This study purposes designing a new aptasensor to detect aflatoxin B1 (AFB1). The AFB1 aptasensor was developed by growing gold nanoparticles on the surface of nickel-based metal-organic framework nanosheets (AuNPs/Ni-MOF) and an electroactive indicator (p-biphenol, PBP). The AFB1 aptamer was immobilized on the AuNPs/Ni-MOF and then hybridized with the complementary DNA (cDNA). PBP was intercalated within the double helix of the cDNA-aptamer. The difference between electrochemical responses of intercalated PBP before and after incubation of AFB1 with the immobilized aptamer was considered as an analytical response. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to monitor the construction processes of the aptasensor. By recording the differential pulse voltammograms of PBP in phosphate buffer (pH 7.0, 0.1M), the linear range and the detection limit of AFB1 were found to be 5.0 × 10-3-150.0ngmL-1 and 1.0 × 10-3ngmL-1 (S/N = 3), respectively. Finally, the designed aptasensor has been successfully used to measure AFB1 in a rice flour sample with satisfying results. Schematic illustrated the different steps of constructing the electrochemical aptasensor based on Au nanoparticles decorated on Ni-metal-organic framework nanosheets and p-biphenol electroactive label for measuring aflatoxin B1 (AFB1).