Bimetallic Metal-organic Frameworks Research Articles

Colorimetric-ratiometric fluorescence sensors dual-mode detection of ofloxacin based on Fe-Ni bimetallic metal-organic frameworks and carbon dots

Colorimetric-ratiometric fluorescence sensors dual-mode detection of ofloxacin based on Fe-Ni bimetallic metal-organic frameworks and carbon dots

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.

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

Exploring Electrocatalytic CO2 Reduction Over Materials Derived from Cu‐Based Metal‐Organic Frameworks

AbstractThe direct valorization of carbon dioxide (CO2) into value‐added chemicals offers an efficient and attractive approach to promoting carbon neutrality. Among the available methods, the electrocatalytic CO2 reduction reaction (eCO2RR) for producing multicarbon products (C2+) is gaining attention owing to its simplicity. However, achieving selective control over product formation remains a challenge. One key issue is the lack of a reliable correlation between the physicochemical properties of electrocatalytic materials and their activity and selectivity. To address this gap, we conducted a model study in which carbonized CuxZny@C materials, derived from metal‐organic frameworks (MOFs), were synthesized with varying Cu/Zn ratios. The pyrolyzed bimetallic MOFs retained key properties of the original MOFs while also developing new characteristics. These subtle changes in physicochemical properties influenced product selectivity. The findings of our study revealed that higher Zn doping favors the formation of single‐carbon (C1) products, whereas it is less favorable for multicarbon (C2+) products. Optimizing the Cu/Zn ratio was emphasized through characterization techniques, which will help guide the design of improved electrocatalytic systems for the eCO2RR process.

An efficient peroxymonosulfate activator derived from metal-organic frameworks: The application of Cu, Mg co-doping strategy

The application of metal-organic frameworks (MOFs)-based catalysts in Fenton-like reactions attracts increasing attention, however, improving the efficiency of these catalysts remains a challenge. Herein, a highly efficient peroxymonosulfate (PMS) activator (CuMg@Fe-MOFs-500) derived from MOFs was successfully synthesized. The results indicated that the Cu and Mg co-doping strategy employed in the fabrication of CuMg@Fe-MOFs-500 significantly enhanced the PMS activation performance, achieving a tetracycline (TC) degradation efficiency of 96.8 % within 60 min. The incorporation of the doped Mg and Cu significantly increased the contents of the oxygen vacancy (OV) and low-valent copper (Cu0 and Cu+), respectively. The interaction between the OV and Cu0/Cu+ became a key factor during the PMS decomposition process. Furthermore, for the first time, the OV content was observed to be positively and negatively linearly correlated with the reaction rate constant (k) and the charge transfer resistance (Rct) of the prepared PMS activators, respectively. Quenching experiments and electron paramagnetic resonance (EPR) tests demonstrated that the predominant reactive species generated during the PMS activation process were SO4•-, •OH, O2•-, and 1O2. It was also shown that the 1O2 primarily originated from O2•- disproportionation, and a self-quenching process between SO4•- and •OH was also observed. The intermediates produced during pollutant degradation induced by PMS-based Fenton-Like reaction exhibited reduced toxicity, as demonstrated by ecotoxicity analysis. This study presented a novel approach for the fabrication of catalyst derived from bimetallic doped MOFs, characterized by a high OV content, for the application in PMS-based Fenton-like reactions.

Development of Recoverable Magnetic Bimetallic ZIF-67 (Co/Cu) Adsorbent and Its Enhanced Selective Adsorption of Organic Dyes in Wastewater.

In the critical domain of wastewater treatment, the development of cost-effective, durable, and recyclable adsorbents with high adsorption capacities remains a significant challenge. This study introduces a novel magnetic bimetallic Metal-Organic Framework (MOF) adsorbent, MZIF-67-Co/Cu, doped with copper ions. The MZIF-67-Co/Cu adsorbent was successfully synthesized and structurally characterized, demonstrating remarkable selectivity for removing methyl orange (MO) from water. This high selectivity is attributed to the adsorbent's high porosity and Lewis base properties at the coordinating metal ion center. The incorporation of Cu ions significantly enhances the porous architecture and increases the number of metal adsorption sites, leading to an impressive maximum MO adsorption capacity of 39.02 mg/g under optimized conditions (0.5 g/L adsorbent concentration, pH 3.0, 250 rpm agitation speed, adsorption time > 10 min). The adsorption kinetics closely follow the pseudo-second-order model, and the isotherm data fit well with the Langmuir model. The primary adsorption mechanisms involve electrostatic attraction and mesoporous interaction. This study highlights MZIF-67-Co/Cu as a highly efficient adsorbent with magnetic recovery capabilities, positioning it as a promising candidate for addressing critical issues in wastewater treatment.

Coupling In nanoclusters and Bi nanoparticles in nitrogen-doped carbon for enhanced CO2 electroreduction to HCOOH

CO2 electrochemical reduction reaction (CO2RR) to formic acid (HCOOH) is beneficial for the recycling of carbon resources, which needs the highly selective catalysts with long-term stability for HCOOH production. In this study, the coupling of In nanoclusters (Inclus) and Bi nanoparticles (Binps) in nitrogen-doped carbon was designed by the thermal decomposition of the mixture of bimetallic MOFs and dicyanamide. When the In/Bi molar ratio was 1:2 (Inclus/Binps-1:2), the hybrid catalyst achieved a HCOOH Faradaic efficiency (FEHCOOH) of 94.5 % at −1.1 V vs reversible hydrogen electrode (RHE) in an H-type electrolysis cell, superior to that of single metal counterparts. Moreover, the Inclus/Binps-1:2 can maintain high stability of structures during the catalytic process, leading to no significant decay of FEHCOOH over 32 h. The enhanced performance of Inclus/Binps-1:2 is attributed to the strong electron interactions induced by the charge transfer between the In and Bi sites in Inclus/Binps-1:2 catalyst. The tuned electronic structure results in an offset effect that optimizes the binding energy to HCOO* intermediate, thus accelerating the CO2 to HCOOH conversion, as proven by the in-situ ATR-SEIRAS and density functional theory (DFT) calculations.

DBD plasma assisted synthesis of Ce-MIL-88B(Fe) with electron-rich CUSs and mixed-valent bimetallic sites for enhanced photo-Fenton performance

Iron-based metal-organic frameworks (Fe-MOFs) are regarded as a kind of prospective catalysts for photo-Fenton process. However, high cost, rate-limiting Fe(III)/Fe(II) circulation and limited metal sites greatly restricted the application of Fe-MOFs in photo-Fenton system. Ce-MIL-88B(Fe) was synthesized with mixed-valent bimetallic sites and tunable coordinated unsaturated metal sites (CUSs) using dielectric barrier discharge (DBD) plasma with waste PET. The incorporation of Ce altered the structure and the electron aggregation, as well as induced structural defects. Ce substitution in Fe-MOFs induced the regulation of the ratio of Fe ions and formation of electron-rich CUSs, which were beneficial for the rapid adsorption and activation of H2O2, thus enhancing the photo-Fenton performance. The effect of reaction conditions on TC degradation was investigated by response surface methodology (RSM) combined with Box-Behnken design (BBD). This study demonstrates a new perspective on the construction of bimetallic MOFs for the photo-Fenton system.