Bimetallic Metal-organic Frameworks Research Articles

Facile synthesis of ZnFe2O4/ZnO/Fe3O4/Fe3N/C composites derived from bimetallic MOFs for efficient electromagnetic wave absorption

A novel metal–organic framework (MOF), ZnFe-MOF, was synthesized using a water phase method. By employing an explosion method with ZnFe-MOF as a precursor, a porous carbon composite electromagnetic wave-absorbing powder, ZnFe2O4/ZnO/Fe3O4/Fe3N/Fe2N/Zn/C (ZFC280), was obtained. This study examined the effects of paraffin filling amount and calcination temperature on the absorption performance of carbon composite materials. Notably, when the mass ratio of the absorber to paraffin was 1:1, the nanocomposite absorber ZnFe2O4/ZnO/Fe3O4/Fe3N/C (ZFC300) exhibited superior electromagnetic wave absorption capability. The ZFC300 sample demonstrated nearly complete absorption of electromagnetic waves across frequencies from 2 to 18 GHz with thicknesses ranging from 1 to 10 mm. Particularly, ZFC300 achieved a minimum reflection loss of −55.32 dB at 4.31 GHz with the 5.46 mm thickness and exhibited the broadest absorption bandwidth of 4.14 GHz at a thickness of 2.0 mm. The primary loss mechanism of the multicomponent and porous ZFC300 was dielectric loss with supplementary magnetic loss. Owing to its excellent absorption performance, the ZFC300 absorber is be a promising candidate for both civilian and military applications.

Efficiently enhancing stability for a low concentration HCHO degradation using hexagonal prism MnCe-MOFs catalysts

The efficient and stable removal of indoor formaldehyde (HCHO) a low concentration, as required by the national standard (≤ 0.08 mg/m3), remains a significant challenge. In this study, we investigated a novel hexagonal prism structure of MnCe-MOFs catalysts, synthesized via the hydrothermal method using DMF (N, N-Dimethylformamide), for the complete degradation of HCHO at ambient temperature. Monometallic and bimetallic MOFs materials, as well as the effects of calcination temperature and the stability of these high-performance catalysts in degrading HCHO were investigated and characterized using EDS, XPS, H2-TPR, IR and ESR. Results demonstrated that HCHO degradation using MnCe-MOFs achieved 97.2% efficiency within 48 hours, maintaining above 96% efficiency after three experimental cycles, exhibiting the highest activity and stability. The high performance was attributed to the columnar structure with abundant pores and a high specific surface area, lower initial reduction temperature, and an abundant presence of surface hydroxyl groups. Moreover, the spherical nanoparticles of MnCe-MOFs were uniformly distributed, and the highly dispersed CeOx provided plentiful active sites, contributing to the catalysts’ high activity and stability.

Progress in MOFs and MOFs-Integrated MXenes as Electrode Modifiers for Energy Storage and Electrochemical Sensing Applications

The global energy demand and environmental pollution are the two major challenges of the present scenario. Recently, researchers focused on the preparation and investigation of catalysts for their capacitive properties for energy storage devices. Thus, supercapacitors have received extensive interest from researchers due to their promising energy storage features and decent cyclic stability/performance. The performance of the supercapacitors are significantly influenced by the physicochemical properties of the electrocatalyst. In this review article, we have compiled the previous reports on the fabrication of MOFs-based composite materials with MXenes for energy storage and electrochemical sensing applications. The metallic and bimetallic MOFs and MOFs/MXenes materials for supercapacitor applications are reviewed. In addition, MOFs/MXenes-based hybrid composites are also compiled towards the determination of various toxic/hazardous materials, such as metal ions like copper ions, mercury ions, and picric acid. We believe that present review article may benefit the researchers working on the preparation of MOFs-based catalysts for supercapacitor and electrochemical sensing applications.

(Fe, Co) oxide nanowires on gold nanoparticles modified MOF-derived carbon nanoflakes for high-efficiency sodium-ion batteries and supercapacitors across electrolytes

The three-dimensional conductive porous carbon nanosheets (CPCN) are from the bimetallic metal-organic framework (MOFs) consisting of organic ligating groups that incorporate zinc and cobalt ions deposited onto a flexible carbon cloth (CC). Utilizing a hydrothermal approach, iron-cobalt oxide (FCO) nanowires are intricately embedded onto CPCN modified with gold (Au), forming a flexible FCO/Au/CPCN@CC electrode. The electrochemical characteristics of electrodes are evaluated in 1 M Na2SO4, supercapacitor's storage capacity is tested at 4 V using 1 M NaPF6 electrolyte. Among its remarkable attributes are a peak energy density of 291.5 W h kg−1 achieved at a power density of 153.85 W kg−1, and even at the maximum power density of 1749.9 W kg−1, it maintains 144.78 W h kg−1. Undergoing 10,000 rounds of GCD, the equipment sustains a capacitance retention of 84.27 %. Moreover, the performance of the FCO/Au/CPCN@CC anode in sodium-ion batteries (SIBs) is assessed. At 0.1C, the discharge capacity reaches 958 mAh g−1, and there is almost no loss after the rate cycle. The Coulomb efficiency surpasses 98 % during 500 cycles at a large C-rate. The integration of Au nanoparticles onto the CPNC surface enhances the energy storage characteristic of the FCO/Au/CPCN@CC composite material in both battery and supercapacitor applications.

A ratiometric fluorescence platform based on bifunctional MOFs for sensitive detection of organophosphorus pesticides

Rapid and precise detection of organophosphorus pesticides (OPs) is of great importance for life health. Herein, a new sensing platform is developed through a dual signal amplification approach for sensitive quantification of OPs, with a bimetallic metal organic framework (UiO-66(Zr/Fe)-NH2) as peroxide-like nanozyme and fluorescent indicator. In the presence of thiocholine (TCh), the hydrolyzate of acetylthiocholine iodide catalyzed by acetylcholinesterase, the catalytic oxidization of o-phenylenediamine by UiO-66(Fe/Zr)-NH2 to strong fluorescent 2,3-diaminophenazine (λem 555nm) is significantly inhibited. OPs-triggered acetylcholinesterase inactivation enables the renaturation of UiO-66(Fe/Zr)-NH2. Interestingly, the introduction of 1,4-dioxane further boosts the amplification of fluorescence signals. By virtue of the recovered fluorescence at 555nm and MOF fluorescence (λem 446nm), the dual signal amplification-based ratiometric fluorescent platform is successfully employed for the selective recognition and sensitive detection of OPs. This work is expected to provide a facile and sensitive method for accurate OPs assay, and make a positive contribution to food safety.

Enhanced Oxygen Evolution Reaction in Alkaline Water Electrolysis Using Bimetallic NiFe Metal-Organic Frameworks Integrated with Carbon Nanotubes

Hydrogen is considered a very clean and highly available renewable energy resource for the future. Water electrolysis (WE) is a conspicuous promising technology to produce hydrogen on a large scale, without generating carbon dioxide. In this study, we prepared bimetallic NiFe-based metal–organic frameworks (MOFs) integrated with CNTs (NiFe–BTC@CNTs) as highly efficient electrocatalysts for the oxygen evolution reaction (OER) in alkaline water electrolysis. Combining NiFe MOFs and CNTs significantly enhanced the electrochemical performance and structural integrity of the catalyst. The NiFe–BTC@CNT (30 wt.% CNTs) demonstrates a significant low overpotential of 230 mV at 10 mA·cm⁻2, superior catalytic activity with a Tafel slope of 36 mV·dec⁻1, and excellent stability under both constant and dynamic operating conditions. These unique characteristics are attributed to the high surface area and abundant active sites provided by the bimetallic MOF structure, combined with the exceptional electrical conductivity and mechanical strength of CNTs. Furthermore, the integration of CNTs improves the dispersion while preventing the agglomeration of MOF particles, ensuring a more uniform and accessible active surface area. This research highlights the potential of the NiFe–BTC@CNT catalysts as high-performance durable electrocatalysts for sustainable hydrogen production, offering a significant advance in the development of advanced materials for energy conversion and storage applications.

Enhancing Hydrogen Evolution Reaction through the Improved Mass Transfer and Charge Transfer by Bimetal Nodes.

The high cost of hydrogen production by water electrolysis severely challenges its commercial application. It is highly desirable to develop efficient electrocatalysts and innovative electrolytic cells. Introducing additional metal nodes to form bimetallic metal-organic framework (MOF) is a simple, feasible strategy to overcome the poor electrocatalytic performance of single-metal MOF. In this study, the hydrothermal method is used to synthesize bimetallic NixCoy-BTC. It is found that for hydrogen evolution reaction (HER), Ni0.8Co0.2-BTC merely requires a potential of -0.203 V (vs reverse hydrogen electrode, RHE) to achieve 10 mA cm-2, which is significantly lower than that of Ni-BTC (-0.341 V vs RHE). Notably, electrochemical impedance spectroscopy (EIS) and distribution of relaxation time (DRT) analysis indicate that NixCoy-BTC has improved charge transfer and mass transfer process, compared with Ni-BTC. Electron paramagnetic resonance (EPR) confirms that Ni0.8Co0.2-BTC has more unpaired electrons than Ni-BTC. Density functional theory (DFT) calculations show that compared with Ni-BTC, NixCoy-BTC is more thermodynamically favorable for the adsorption of H+, OH-, and H2O. It demonstrates that the change of mass transfer caused by bimetallic nodes and the delicate variation of MOF surface play an important role in the electrochemical process. Moreover, a novel electrolytic cell was developed using a methanol oxidation reaction (MOR) to replace oxygen evolution reaction (OER). In this MOR-based electrolytic cell, a current density of 50 mA cm-2 can be achieved at only a cell voltage of 1.85 V, which is lower than the 2.22 V of OER-based electrolytic cell, suggesting that 16.7% electric energy can be saved. At the same time, the Faraday efficiency (FE, 98.2%) of the MOR-based cell is higher than that (94.5%) of the OER-based cell. This research offers a promising strategy for low-cost hydrogen production.

A general flame aerosol route to kinetically stabilized metal-organic frameworks

Metal-organic frameworks (MOFs) are highly attractive porous materials with applications spanning the fields of chemistry, physics, biology, and engineering. Their exceptional porosity and structural flexibility have led to widespread use in catalysis, separation, biomedicine, and electrochemistry. Currently, most MOFs are synthesized under equilibrium liquid-phase reaction conditions. Here we show a general and versatile non-equilibrium flame aerosol synthesis of MOFs, in which rapid kinetics of MOF formation yields two distinct classes of MOFs, nano-crystalline MOFs and amorphous MOFs. A key advantage of this far-from-equilibrium synthesis is integration of different metal cations within a single MOF phase, even when this is thermodynamically unfavorable. This can, for example, produce single-atom catalysts and bimetallic MOFs of arbitrary metal pairs. Moreover, we demonstrate that dopant metals (e.g., Pt, Pd) can be exsolved from the MOF framework by reduction, forming nanoclusters anchored on the MOF. A prototypical example of such a material exhibited outstanding performance as a CO oxidation catalyst. This general synthesis route opens new opportunities in MOF design and applications across diverse fields and is inherently scalable for continuous production at industrial scales.

2D Membranes Interlayered with Bimetallic Metal-Organic Frameworks for Lithium Separation from Brines.

Efficient lithium extraction from salt lakes is essential for a sustainable resource supply. This study tackles the challenge of separating Li+ from Mg2+ in complex brines by innovatively integrating two-dimensional (2D) graphene oxide (GO) with bimetallic metal-organic frameworks (MOFs). Zn2+ and Co2+ ions are confined within GO interlayers through an in situ synthesis, forming a 2D Zn-Co MOFs/GO membrane (Zn-Co-GOM). This design exploits the unique advantages of bimetallic MOFs, including enhanced structural stability and superior ion separation capabilities due to the synergistic effects of Zn and Co. The Zn-Co-GOM demonstrates an impressive separation factor of 191 for Li+ over Mg2+, significantly surpassing traditional membranes. This exceptional selectivity is achieved through a combination of size exclusion effects and ion transport energy barriers. Our approach not only enhances the practical application of membrane technology for lithium extraction from salt lakes but also provides valuable insights into the underlying separation mechanisms.

Efficient Capture of Phosphate From Aqueous Media Using Bimetallic La‐Zr‐MOF

ABSTRACTDeposition of excessive phosphate in natural water column caused several issues, like the eutrophication and destruction of aquatic ecosystems. Adsorption has been an effective and convenient method for phosphate elimination. Herein, a novel bimetallic metal–organic framework adsorbent, namely, La‐Zr‐MOF, was prepared, and the morphology, crystallite, characteristic functional groups, specific surface area, and composite material surfaces were analyzed using XRD, FT‐IR, SEM‐EDS, and BET. The adsorption performance of the adsorbent was systematically evaluated by batch adsorption experiments, and the adsorption thermodynamic and kinetic properties were analyzed. The results reveal that La‐Zr‐MOF exhibits a high selectivity and sorption performance for phosphate, and the adsorption of La‐Zr‐MOF follows the Langmuir and pseudo–second‐order models; the phosphate removal procedure is a chemisorption accompanied by an endothermic reaction, and the maximum capacity was 127.7 mg g−1. Combined with batch adsorption experiments, kinetic and thermodynamic studies and various characterization analyses together revealed the phosphate removal mechanism, mainly ligand exchange and electrostatic interactions.

Powering Hydrogen Evolution Reaction by Precise Control Over A Cu‐Ni Bimetallic Electrocatalyst

ABSTRACTPrecious metals are effective catalysts for the hydrogen evolution reaction, but their high cost with complicated operation steps drives people to search for non–noble‐metal alternatives. Building rational design concept for efficient electrocatalyst relies on the capability to control the structure and composition. Herein, a Ni/Cu bimetallic mesoporous MOFs with 4,4′,4″‐(1,3,5‐triazine‐2,4,6‐triyl)tribenzoic acid as the robust ligand has been assembled via a one‐step solvothermal method. Due to the extensive conjugate plane and high nitrogen content, the catalyst possesses large pore size of 17 nm and fast electron transfer rate, which favors hydrogen bubble overflow and exposes more active sites to solid–liquid interfaces. The bimetallic interaction between highly conductive Cu ions and Ni ions allows it to improve charge migration and realize excellent conductivity. The functionalized electrode requires an overpotential of 132 mV to achieve 10 mA current density with a small Tafel slope (87.7 mV·dec−1) and continuous electrolysis for 24 h.

Engineering the Co/CoO heterostructure to trigger the in-situ generation of abundant high-valent cobalt species for enhanced electroreduction of nitrate to ammonia

The CoO-based materials are promising candidates for electrochemical nitrate reduction reaction to ammonia (eNO3RR). Herein, Zn/Co bimetallic MOFs are adopted to construct Co/CoO Schottky heterostructures, where the Co-CoO interfaces are engineered by controlling the Zn/Co ratio. The interface-optimized Co/CoO displays an NH3 yield of 713 µmol/h cm−2 and a maximum Faradaic efficiency of 99.16 % due to the synergistic effect between CoO and Co and abundant oxygen vacancies. The more the Co-CoO interfaces, the more the in-situ generated high-valent cobalt species (CoOOH), and the higher the catalytic performance. Therefore, the high-valent cobalt species are considered the true active sites. When used as a cathode in a rechargeable Zn-NO3− battery, the Co/CoO heterostructure achieves a power density of 4.7 mW cm−2 and an NH3 yield of 131.7 µmol/h cm−2 with robust working stability.

Photocatalytic degradation of methylene blue using a Cu2+-modified bimetallic titanium-based metal organic framework (MIL-125) photocatalyst with enhanced visible light activity.

Cu-modified TiO2 nanoparticles derived from MIL-125 were prepared by solvothermal method for the photocatalytic degradation of methylene blue under visible light illumination. For boosting the photocatalytic performance as well as the physicochemical properties of bare sample, 2 wt % Cu2+ ions were integrated into the nodes of the MIL-125 framework. The results showed that incorporation of 2 wt % Cu2+ ions into the MOF framework had significant effects on the crystallographic structure and morphological and optical properties of photocatalytic samples, as well as catalytic activity for the methylene blue degradation reaction. The high activity profile of Cu-modified TiO2 nanoparticles derived from MIL-125 might be attributed to the increased thermal stability, lower band gap energy, and smaller crystallite size of the sample. Activity tests were carried out at five varying MB initial concentrations and four different pH values. According to the findings, an increase in initial dye concentration resulted in a decrease in degradation efficiency. It was observed that increasing the pH value in the range of 3-11 initially led to higher degradation rates until pH 7, after which the degradation rate began to decline.

Bimetallic FeCo metal–organic framework based cascade reaction system: Enhanced peroxidase activity for antibacterial performance

Metal-organic frameworks (MOFs), as a peroxidase (POD), can catalyze the conversion of H2O2 to reactive oxygen species (ROS) for antibacterial application. To achieve strong antibacterial activity, it is necessary to improve the enzyme-like activity of MOFs. In this study, FexCoMOF was synthesized by incorporating Co(II) to improve the electron transfer of Fe(III)/Fe(II), which enhanced its redox capacity as a nanozyme and further promoted the generation of hydroxyl radical (⋅OH), exhibiting higher POD activity. Doping with different amounts of Co(II) altered the particle size, specific surface area, and surface defects of FexCoMOF, thus exhibiting differential enzyme-like activities. Additionally, a glucose-responsive enzyme cascade reaction system based on Fe4CoMOF/glucose oxidase (GOx) was established. In the presence of glucose, the in situ-generated substrate H2O2 was in contact with the catalytic site and the generated gluconic acid enabled Fe4CoMOF to maintain maximum enzyme activity under physiological pH conditions, avoiding damage caused by the use of exogenous high concentrations of H2O2. In the in vitro antibacterial experiment, the minimum inhibitory concentration (MIC) of Fe4CoMOF/GOx was 10 μg mL−1 for Escherichia coli (E. coli) and 5 μg mL−1 for Staphylococcus aureus (S. aureus) (∼108 CFU mL−1). The increase in enzyme activity resulted in a considerable reduction in the dose of the antibacterial agent, which was conducive to improving bio-safety. The in vivo experiment in mice demonstrated that the glucose-responsive Fe4CoMOF-based cascade reaction system had excellent antibacterial properties and remarkably promoted wound healing. The antibacterial agent based on bimetallic MOF developed in this work provides a new idea for cascade catalytic antibacterial therapy and will have remarkable application prospects in biomaterials and nanomedicine.

Dual metal centers within a water-stable Co/Ni bimetallic metal-triazolate framework contribute to durable photocatalysis for water treatment.

Bimetallic metal-organic frameworks (MOFs) have been studied extensively in various fields, including photocatalytic and electrocatalytic applications. The enhanced catalytic activity is typically attributed to the synergistic effect of the two metals, often without further explanation. Here, we demonstrate a CoNi-bimetallic triazolate MOF with fixed metal occupancy within the MOF's secondary building unit. Due to the difference in electronegativity and so on, the charge redistribution between the two metal centers could be responsible for the enhanced photocatalytic activity. In addition, the metal(II)-triazolate MOFs we synthesized exhibit unique metal-N coordination and a strong bond between the metal center and triazole ring. Therefore, their crystal structure and high porosity are highly retained even after exposure to humid environments for several months or stirring in water for several days. Overall, the CoNi-bimetallic triazolate MOF combines the excellent water stability and high surface area of its two monometallic counterparts. It can be further tailored to yield the highest colloidal stability during photocatalytic water treatment. As a result, the dual metal centers within the bimetallic MOF, combined with boosted colloidal stability, demonstrate the highest reactive oxygen species generation and promising antibacterial performance compared to their Ni- or Co-based counterparts. These findings shed light on the future design of robust MOF-based photocatalysts, particularly bimetallic ones.

Integration of polyoxometalate into defective UiO-66-NH2(Zr/Hf) for visible-light-driven hydrogen photogeneration

UiO-66 plays a crucial role in photocatalytic systems due to its superior stability and tunability. However, the charge transfer from organic ligands to metals is rarely involved in the photo-excitation of the pristine material. Herein, several Keggin-type Cs2.5H0.5PW12O40 (CsPW) were successfully incorporated into a bimetallic metal-organic framework (MOF) using a one-pot, one-step method, resulting in a series of defective CsPW@UNH(Hf-Zr) as optimized photocatalysts for visible-light-driven hydrogen evolution. Further investigations demonstrate that a Z heterojunction mechanism proceeds in the CsPW@UNH(0.65Hf) heterojunction to boost the charge separation via the chemical interaction between the CsPW and UNH(0.65Hf) components. The hydrogen evolution rate for 5 %CsPW@UNH(0.65Hf) is nearly two orders of magnitude greater than that of the bare UNH(Zr). The coexistence of Hf3+ and Zr3+ was observed in defective polyoxometalate-encapsulated MOF (POM@MOF) for the first time during photocatalysis, confirming the successful conjugated π electrons transition from the amine-containing ligand to bimetallic cluster. This study offers a novel guideline for exploring efficient MOF-based photocatalysts through defect engineering.

Coencapsulating TMB Probes and Bimetallic MOF Nanozymes in a Hydrogel Patch for Fabricating Reusable Visual VC Sensors.

As a typical chromogenic probe, 3,3',5,5'-tetramethylbenzidine (TMB) has been widely applied in the field of visual detection due to its low toxicity and highly sensitive response. Due to the hydrophobic nature of TMB, encapsulating it into a hydrogel, which serves as an ideal matrix for wearable sensors, presents significant challenges that complicate the fabrication of visual wearable devices. Herein, the TMB probe and bimetallic MOF nanozymes are coencapsulated in a hydrogel patch for the fabrication of reusable visual sensors. Hydrophobic TMB is oxidized to hydrophilic ox-TMB by a bimetallic MOF (CuFe-MOF), allowing its diffusion into a hydrophilic agarose hydrogel patch, where it is reduced back to TMB. This process allows the coimmobilization and coencapsulation of CuFe-MOF and TMB within the hydrogel patch. Leveraging the color change between TMB and ox-TMB, as a proof-of-concept application, a reusable visual "On-Off-On" sensor is simply constructed and successfully applied to detect vitamin C in human sweat. Color changes can be quickly read by the naked eye or by smart devices without the need for external equipment. Meanwhile, based on the reversible conversion relationship between TMB and ox-TMB, a reusable sensor construction strategy is proposed. This approach not only facilitates the use of a TMB probe in hydrogel applications but also offers inspiration for the development of point-of-care testing equipment, demonstrating significant application potential.

Cu-Co binary metal-organic framework nanosheets for highly efficient degradation of norfloxacin using the Fenton-like process

Efficient catalyst development for hydrogen peroxide activation is crucial in advanced oxidation processes (AOPs) technology. In this study, we successfully synthesized a bimetallic organic framework incorporating Cu-Co MOF nanosheets via a one-pot strategy. The subsequent Cu-Co MOF nanosheets demonstrated outstanding oxidative activity, achieving a remarkable 95.37 % removal of norfloxacin (NOR), surpassing the efficacy of Cu MOF/H2O2 or Co MOF/H2O2 nanosheets alone by 1.34 and 2.59 times, respectively. Density functional theory (DFT) calculations revealed that the bimetallic MOF nanosheets: firstly, enhanced optimization of the adsorption energy for H2O2 activation; and secondly, facilitated the cleavage of the O–O bond in H2O2. Furthermore, electrochemical impedance spectroscopy (EIS) analysis demonstrated a significant improvement in interfacial electron transfer once dual-reaction centers were introduced into the Cu-Co MOF nanosheets. Electron paramagnetic resonance analysis and quenching tests confirmed that 1O2, ·O2− and ·OH were involved in NOR degradation. Reasonable NOR degradation pathways were proposed by analysing the results of LC-MS and DFT calculations. Moreover, the synthesized nanosheets exhibited excellent reusability, with more than 90.00 % NOR removal achieved using the Cu-Co MOF nanosheets/H2O2 system after reuse on 3 occasions. These findings underscore the effectiveness of bimetallic MOF construction in developing highly efficient MOF-based Fenton-like catalysts. Also highlighted here is the promising role of Cu-Co MOF nanosheets in wastewater treatment, particularly for the removal of antibiotics.

Self-exfoliating Bimetallic Metal–Organic Framework Layer with Intralayer π–π Interactions for Efficient Electrical Transport and CO2 Electroreduction

Self-exfoliating Bimetallic Metal–Organic Framework Layer with Intralayer π–π Interactions for Efficient Electrical Transport and CO₂ Electroreduction

Advances in bimetallic metal organic frameworks (BMOFs) based photocatalytic materials for energy production and waste water treatment

Advances in bimetallic metal organic frameworks (BMOFs) based photocatalytic materials for energy production and waste water treatment