Bimetallic Organic Framework Research Articles

Exploring the role of Cu/Mn-BTC catalyst in the selective catalytic reduction of NOx by C3H6: Synthesis to in-situ DRIFTS study

The choice of reducing agents and their impact on catalytic performance are important aspects of selective catalytic reduction (SCR) technology. Marking the inaugural use of C3H6 as a reducing agent with the BTC catalyst, a bimetallic organic framework (xCu-Mn-BTC) was prepared and tested as a catalyst for NOx reduction under oxygen-enriched conditions. The results showed that NO conversion was influenced by the ratio of Cu and Mn metals, among which 3.2Cu-Mn-BTC exhibited the highest denitrification performance (80 % NOx conversion and 94 % N2 selectivity) at 300 °C. From the characterization results, Cu was successfully incorporated into the BTC framework and 3.2Cu-Mn-BTC became spherical grains with smaller particle sizes. The high catalytic activity of 3.2Cu-Mn-BTC was due to the presence of more adsorbed oxygen Oα (89.7 %) and Cu2+ (63 %) species than in the other catalysts. The TPR peak of xCu-Mn-BTC shifted to a lower temperature and showed better reducibility. The Py-FTIR study shows that xCu-Mn-BTC contained more Lewis acid but no Brønsted acid, because Cu increased the concentration of Lewis acid on the catalytic surface (42 to 46 mmol/g), and Lewis acid plays an important role in the C3H6-SCR of NOx.

Metal-organic frameworks with fine-tuned interlayer spacing for microwave absorption.

Designing a functional, conductive metal-organic framework (cMOF) is highly desired. Substantial efforts have been dedicated to increasing the intralayer conjugation of the cMOFs, while less dedication has been made to tuning the interlayer charge transport of the metal-organic nanosheets for the controllable dielectric property. Here, we construct a series of conductive bimetallic organic frameworks of (ZnxCu3-x) (hexahydroxytriphenylene)2 (ZnCu-HHTP) to allow for fine-tuned interlayer spacing of two-dimensional frameworks, by adjusting the ratios of Zn and Cu metal ions. This approach for atomistic interlayer design allows for the finely control of the charge transport, band structure, and dielectric properties of the cMOF. As a result, Zn3Cu1-HHTP, with an optimal dielectric property, exhibits high-efficiency absorption in the gigahertz microwave range, achieving an ultra-strong reflection loss of -81.62 decibels. This study not only advances the understanding of the microstructure-function relationships in cMOFs but also offers a generic nanotechnology-based approach to achieving controllable interlayer spacing in MOFs for the targeted applications.

Designed Synthesis of Fe/Zr Bimetallic Organic Framework to Enhance the Selective Conversion of H2S to Sulfur.

The development of stable and effective catalysts to convert toxic H2S into high value-added sulfur is essential for production safety and environmental protection. However, the inherent defects of traditional iron- and zirconium-based catalysts, such as poor activity, high oxygen consumption, and low sulfur selectivity, limit their further developments and applications. Herein, the Fe-Zr bimetallic organic framework FeUIO-66(x) with different cubic morphologies was synthesized via a facile solvothermal method. The results indicate that the introduction of Fe not only increases the specific surface area and weak L-sites of the catalyst without changing its crystal structure, which provides enough reaction space and more active sites for the adsorption and activation of H2S, but also reduces the activation energy of the reaction, significantly promoting the selective oxidation of H2S. As a result, the as-obtained FeUIO-66(1) catalyst exhibits the highest desulfurization activity and superior durability and water resistance stability, and its H2S conversion and sulfur selectivity within 50 h are 100 and 88%, respectively. More importantly, the structure of the catalyst after the desulfurization reaction is consistent with that of the fresh counterpart. The study offers new insights into the development of effective and stable bimetallic catalysts to eliminate H2S and recycle sulfur.

Bimetallic NH2-MIL-101(Fe, Co) as highly efficient photocatalyst for nitrogen fixation

Developing effective catalysts for N2 photofixation at ambient conditions is highly desirable but still challenging. Herein, we reported a novel Co-doped NH2-MIL-101(Fe) (NM-Fe) bimetallic organic framework (BMOF) for visible-light-driven catalytic N2 fixation. It was found that the doping of Co ions could effectively enhance light-harvesting, reduce the conduction band potential, suppress the recombination of photogenerated carriers, and promote the activation of N2. Consequently, the photocatalytic N2 reduction efficiency of bimetallic NH2-MIL-101(Fe, Co) (NM-Fe-Co) was obviously boosted. The sample with the optical Co/Fe molar ratio of 0.15, namely NM-Fe-0.15Co, enabled an ammonia evolution rate up to 335.7 µmol g−1 h−1 without the aid of any sacrificial agents, a 4.4-fold increase over the monometallic NM-Fe baseline. Additionally, the bimetallic NM-Fe-Co displayed excellent stability. The possible reaction mechanism of nitrogen fixation over NM-Fe-Co was proposed based on in-situ infrared analysis. Our study demonstrates a promising strategy for designing potent MOF-based catalysts for N2 photofixation.

Water-Stable Pillared Three-Dimensional Zn-V Bimetal-Organic Framework for Promoted Electrocatalytic Urea Oxidation.

Urea oxidation reaction (UOR) is one of the potential routes in which urea-rich wastewater is used as a source of energy for hydrogen production. Metal-organic frameworks (MOFs) have promising applications in electrocatalytic processes, although there are still challenges in identifying the MOFs' molecular regulation and obtaining practical catalytic systems. The current study sought to synthesize [Zn6(IDC)4(OH)2(Hprz)2]n (Zn-MOF) with three symmetrically independent Zn(II) cations connected via linear N-donor piperazine (Hprz), rigid planar imidazole-4,5-dicarboxylate (IDC3-), and -OH ligands, revealing the 3,4T1 topology. The optimized noble-metal-free Zn0.33V0.66-MOF/NF electrocatalysts show higher robustness and performance compared to those of the parent Zn monometallic MOF/NF electrode and other bimetallic MOFs with different Zn-V molar ratios. The low potential of 1.42 V (vs RHE) at 50 mA cm-2 in 1.0 M KOH with 0.33 M urea required by the developed Zn0.33V0.66-MOF electrode makes its application in the UOR more feasible. The availability of more exposed active sites, ion diffusion path, and higher conductivity result from the distinctive configuration of the synthesized electrocatalyst, which is highly stable and capable of synergistic effects, consequently enhancing the desired reaction. The current research contributes to introducing a practical, cost-effective, and sustainable solution to decompose urea-rich wastewater and produce hydrogen.

Ratiometric electrochemical determination of hydroxyl radical based on graphite paper modified with metal-organic frameworks and impregnated with salicylic acid.

Hydroxyl radical (•OH) detection is pivotal in medicine, biochemistry and environmental chemistry. Yet, electrochemical method-specific detection is challenging because of hydroxyl radicals'high reactivity and short half-life. In this study, we aimed to modify the electrode surface with a specific recognition probe for •OH. To achieve this, we conducted a one-step hydrothermal process to fabricate a CoZnMOF bimetallic organic framework directly onto conductive graphite paper (Gp). Subsequently, we introduced salicylic acid (SA) and methylene blue (MB), which easily penetrated the pores of CoZnMOF. By selectively capturing •OH by SA and leveragingtheelectrochemical signal generated by the reaction product, we successfully developed an electrochemical sensor Gp/CoZnMOF/SA + MB. The prepared sensor exhibited a good linear relationship with •OH concentrations ranging from 1.25 to 1200 nM, with a detection limit of 0.2 nM. Additionally, the sensor demonstrated excellent reproducibility and accuracy due to the incorporation of an internal reference. It exhibited remarkable selectivity for •OH detection, unaffected by otherelectrochemically active substances. The establishment of this sensor provides a way to construct MOF-modified sensors for the selective detection of other reactive oxygen species (ROS), offering a valuable experimental basis for ROS-related disease research and environmental safety investigations.

NiCo bimetallic metal-organic framework (NiCo-MOFs) with distinct morphologies for efficient HER activity

Developing a cost-effective and efficient electrocatalyst for green hydrogen production is a critical yet challenging endeavor. In this study, we present a straightforward solvothermal method for crafting a NiCo bimetallic organic framework (NiCo-MOF) employing three unique ligands. Our research delves into exploring the electrocatalytic activity of these NiCo-MOF rods in the context of the hydrogen evolution reaction (HER). The NiCo-MOF rods exhibit impressive HER performance, necessitating a mere 125 mV overpotential at −10 mA cm−2. Notably, these NiCo-MOF rods exhibit a small Tafel slope of 78 mV dec−1, alongside a higher carbon composition, which contributes to excellent mass and electron transfer efficiency during HER. This article contributes valuable insights into the utilization of various ligands in MOF synthesis for the development of electrocatalysts tailored to green hydrogen production.

Simple synthesis, characterization and mechanism of Fe/Zr bimetallic-organic framework for Cr (VI) removal from wastewater

Iron-zirconium bimetallic metal-organic frameworks (MOFs) materials were synthesized by a one-step solvothermal method with abundant active sites for the efficient removal of Cr (VI) ions from wastewater. The as-prepared Fe/Zr-MOFs composites were analyzed by the XRD, FTIR, SEM, TEM, and XPS. The effects of temperature, pH, initial Cr (VI) ion concentration, and co-existing ions on the adsorption properties of the Fe/Zr-MOFs composites were verified. The best removal efficiency of the Fe/Zr-MOFs composites was observed at pH = 5, with the concentration of Cr (VI) ion 20 mg/L under 303 K. In addition, the adsorption process of Cr (VI) by Fe/Zr-MOFs materials consisted with the Langmuir isothermal adsorption model, indicating that the adsorption process is a predominantly uniform monolayer adsorption. Kinetic modelling confirmed that the adsorption process of the material is dual physical and chemical adsorption. The thermodynamic analysis confirmed that the adsorption of Cr (VI) by Fe/Zr-MOFs was a spontaneous feasible, heat-absorbing process. The removal rate was up to 82% after five cycle reused experiments, suggesting the potential practical application of the material. The outperformance of the as-prepared materials was attributed to the combination of the advantages of Fe-MOF and Zr-MOF. Of note, a possible adsorption mechanism was proposed. That is, the adsorption process of the material is a dual physical and chemical adsorption, which mainly includes electrostatic interactions, Chemical coordination, and redox reactions.

Performance study of phosphate removal from water using synergistic interaction between lanthanum-magnesium bimetallic organic frameworks and polyethyleneimine

Aiming at the water solubility of Mg-MOFs and the problems of unstable adsorption performance and low life of pure MOFs caused by metal leakage, lanthanum and polyethyleneimine co-doped Mg-MOFs (2.0LMBP-2.5) were synthesized by solvothermal and impregnation methods. 2.0LMBP-2.5 not only has strong resistance for co-existing anions and acid-base, but also has excellent reusability and stability. Its maximum phosphate adsorption capacity was 514.15 mg·g−1. The phosphate removal rate reached 90.53 %-96.04 % in the pH range of 3.0–11.0. The results of kinetic, isothermal adsorption and thermodynamics showed that the phosphate adsorption process of 2.0LMBP-2.5 was a spontaneous heat absorption process and dominated by monolayer adsorption and chemisorption. FT-IR spectroscopy and XPS revealed a synergistic mechanism between MOFs and polyethyleneimine. The introduction of lanthanum improved the coordination metal bond strength of Mg-MOFs, effectively overcame the water solubility problem of Mg-MOFs. The introduction of lanthanum and polyethyleneimine significantly increased the adsorption capacity of Mg-MOFs, from 21.79 to 273.61 mg·g−1 and 273.61 to 514.15 mg·g−1, respectively.

Ni/Co bimetallic organic frameworks nanospheres for high-performance electrochemical energy storage

Ni/Co bimetallic organic frameworks nanospheres for high-performance electrochemical energy storage

In-situ Ni-doped V-MOF ultra-thin nanosheet arrays on Ni foam for high-performance hybrid supercapacitors

Bimetallic organic frameworks possess distinctive structural and component benefits that make them essential materials for energy storage devices with outstanding capabilities. Here, ultra-thin 2D VNi-MOF nanosheet arrays (NSAs) have been in-situ grown on nickel foam (NF) which served as both the current collector and the Ni source by pretreatment and one-step solvothermal method and used as an efficient electrode material for high performance supercapacitors. Benefiting from its ultra-thin 2D NSAs structure and the synergy of bimetallic ions, the VNi-MOF NSAs/NF exhibits a high specific capacity performance (516.5 C g−1 at 1 A g−1) and outstanding cycling stability (85.6 % capacity retention over 12, 000 cycles at 20 A g−1). Battery-type VNi-MOF NSAs/NF and capacitive-type AC are integrated to assemble a HSC. The prototype HSC achieves a remarkably high energy density of 43 Wh kg−1 (at 800 W kg−1), which demonstrates the great potential of VNi-MOF (bimetallic organic framework) as a HSC electrode.

In-situ grown nickel iron bimetal organic frameworks from activated Ni foam for efficient energy storage and electrocatalysis: Study of metal ratio and nickel precursor effects

Ex-situ fabrication of electroactive electrodes encounters serious peeling off problems. Nickel foam (NF) shows promise as conductive substrate of electroactive electrodes due to high surface area, porosity and conductivity. To broaden NF applications and enhance attachments, applying in-situ growth for establishing efficient active materials on NF is necessary. In this study, nickel iron bimetal organic frameworks (NiFeMOF) are firstly synthesized from activated NF as electroactive electrodes for energy storage and electrocatalysis. Metal ratio and nickel precursor effects are studied to elucidate growing mechanism of electroactive materials. The optimal NiFeMOF/NF presents the highest specific capacitance (CF) of 2017.9 F/g at 20 mV/s, while MOF/NF electrodes prepared with only Ni and Fe respectively show smaller CF values of 622.1 and 1121.8 F/g. The superior electrocatalytic ability is achieved by NiFeMOF/NF. Inclusion of additional Ni salts is necessary for synthesizing Ni-MOF on NF with improved energy storage ability, but that prepared without addition of Ni salt exhibits better electrocatalytic ability. Trade-off between electrochemical surface area and electrical conductivity is proved as crucial factor in designing electroactive materials for energy storage and electrocatalytic water splitting. This study brings novel insights into establishment of effective electroactive materials for electrochemical systems using simple concepts and techniques.

In-situ co-precipitation of Bi-MOF derivatives for highly sensitive electrochemical glucose sensing

Bimetallic organic frameworks (Bi-MOFs) have been recognized as one of the hotpots for electrochemical sensing due to their high surface area, abundant active sites, tunable structures and porosity. However, inadequate conductivity and hidden active site of MOFs remain as great challenges, hindered its further development. Here, an in-situ co-precipitation strategy was proposed for preparing sophisticated hierarchical Bi-MOF derivatives with excellent glucose sensing. Firstly, uniform CuO nanorods as the precursor are synthesized in situ on a Carbon Cloth (CC). Subsequently, Cu-BTC and Co-BTC were co-precipitated on the precursor, while the significant effect of incremental Co2+ doping concentration was investigated. Finally, Cu/Co-MOF derivatives are successfully obtained by controlled thermal structural transformation. Due to the synergistic effect of bimetallic oxides and the exposed active sites, the prepared sensing electrode exhibits high sensitivity (4.93 mA mM−1 cm−2), fast response time (2.9 s), and outstanding long-term stability (30 days). This study proposes a practical method for in-situ synthesizing hierarchical Bi-MOF derivatives, which provides wide-ranging prospects in the field of electrochemical sensing.

Bimetallic MOF derived mesoporous structure of Ru doped SnO2 enable high-sensitivity gas sensors for triethylamine in high humidity

Mesoporous metal oxides have been reported as promising semiconductor gas sensing materials, showing great potential in detecting volatile organic compound (VOC) pollutants in the air. Here, we present the use of mesoporous Ru doped SnO2 oxide semiconductor, derived from a bimetallic organic framework (MOF), as a composite material for high-performance TEA gas sensing. Mesoporous structure of bimetallic MOF-derived composites synthesised using a one-step method, has a high porosity and large specific surface area (69.48 m2 g−1), which can enhance the number of sensing reaction sites and improve its capturing ability for the target gas. Moreover, the in-situ substitution of Ru3+ ions for Sn4+ ions can adjust the carrier concentration. Therefore, the synthesized mesoporous 0.4 mol% Ru-SnMOF@SnO2 exhibits high sensitivity, excellent selectivity, fast response kinetics, and good long-term stability for TEA sensing at 250 °C. Exceptionally, there is still an impressive response (S = 125.5–100 ppm) to triethylamine at 80 % RH. The relative humidity was set at 25 °C.

N-Doped Graphene Quantum Dots Incorporated into NiCo Bimetallic-Organic Framework as an Electrocatalyst for Alkaline Water Splitting

N-Doped Graphene Quantum Dots Incorporated into NiCo Bimetallic-Organic Framework as an Electrocatalyst for Alkaline Water Splitting

Porous layered ZnV2O4@C synthesized based on a bimetallic MOF as a stable cathode material for aqueous zinc ion batteries.

Vanadium-based oxides are considered potential cathode materials for aqueous zinc ion batteries (AZIBs) due to their distinctive layered (or tunnel) structure suitable for zinc ion storage. However, the structural instability and sluggish kinetics of vanadium-based oxides have limited their capacity and cycling stability for large-scale applications. To overcome these shortcomings, here a porous vanadium-based oxide doped with zinc ions and carbon with the molecular formula ZnV2O4@C (ZVO@C) as the cathode material is synthesized by the pyrolysis of a bimetallic MOF precursor containing Zn/V. This electrode demonstrates a remarkable specific capacity of 425 mA h g-1 at 0.5 A g-1 and excellent cycling stability with about 97% capacity retention after 1000 cycles at 10 A g-1. The excellent electrochemical performance of ZVO@C can be attributed to more reaction active sites and the faster reaction kinetics for zinc ion diffusion and storage brought about by the porous layered spinel-type tunnel structure with high surface area and massive mesoporosity, as well as the enhanced electron transport efficiency and more stable channel structure achieved from the doped conductive carbon. The reaction mechanism and structural evolution of the ZVO@C electrode are analyzed using X-ray diffraction and X-ray photoelectron spectroscopy, revealing the formation of a new phase of ZnxV2O5·nH2O during the first charge, which participates in reversible cycling together with ZVO@C during the charging and discharging processes. Moreover, the energy storage mechanism is revealed, in which zinc ions and hydrogen ions jointly participate in intercalation and extraction. The present study demonstrates that constructing composite vanadium-based oxides based on bimetallic organic frameworks as precursor templates is an effective strategy for the development of high-performance cathode materials for AZIBs.

An Au bipyramids@CuZn MOF core-shell nanozyme enables universal SERS and a colorimetric dual-model bioassay.

In this study, a new type of gold nano-bipyramids@CuZn bimetallic organic framework (AuNBPs@CuZn MOF) nanozyme with high peroxidase (POD)-like activity and surface enhanced Raman scattering (SERS) activity was constructed with a special core-shell structure, which can catalyze the oxidation of TMB (colourless and Raman-inactive) into ox-TMB (blue and Raman-active). An AuNBPs@CuZn MOF-enabling universal SERS and colorimetric dual-model bioassay was thus developed for biomolecules with excellent performance, and has promising application prospects in the biosensing fields.

Recent progress in bimetallic-organic framework materials and their derivatives for supercapacitors

In this article, the preparation methods, morphology control and multi-components of bimetallic-organic frameworks and their derivative materials for supercapacitors are briefly reviewed.

Trifunctional electrocatalysts based on a bimetallic nanoalloy and nitrogen-doped carbon with brush-like heterostructure.

Trifunctional ORR/OER/HER catalysts are emerging for various sustainable energy storage and conversion technologies. For this function, employing materials with 1D structures leads to catalysts having limited surface area and structural robustness. Instead of 1D catalysts, heterostructured catalysts (i.e., catalysts consisting of interfaces created by combining diverse structural components) have attracted much attention due to their high efficiency. We have fabricated a directly grown 1D-1D heterostructured bimetallic N-doped carbon trifunctional catalyst based on Fe/Co bimetallic-organic frameworks, forming nanobrushes (FeCoNC-NB) with improved resistance to collapsing and substantial numbers of exposed active sites. The secondary 1D structure of this design contributes to creating interparticle conductive networks. By combining the brush-like heterostructure, FeCo alloy active sites, and N-doped carbon as support and for encapsulation of the metal, the catalyst features a high ORR Eonset value (1.046 V), low OER overpotential (363 mV), and comparable HER overpotential (254 mV) in alkaline electrolyte. Zn-air batteries with FeCoNC-NB demonstrate a power density of 195 mW cm-2 and a superior battery life of up to 350 h. Self-powered FeCoNC-NB-based water electrolyzers as energy conversion devices are also demonstrated. This work drives the progress of trifunctional catalysts based on heterostructured nonprecious metal N-doped carbon for energy storage and conversion developments.

A label-free electrochemical biosensor based on a bimetallic organic framework for the detection of carbohydrate antigen 19-9.

Carbohydrate antigen 19-9 (CA19-9) is an important marker for pancreatic cancer, ovarian cancer and other tumors, and its rapid and stable detection is the basis for early diagnosis and treatment. In this paper, a label-free electrochemical immunosensor for the sensitive detection of CA19-9 has been developed. First, the synthesis of two novel core-shell bimetallic nanomaterials, namely Ce-MOF-on-Fe-MOF and Fe-MOF-on-Ce-MOF, was accomplished using the MOF-on-MOF approach. The poor electrical conductivity of MOF materials was addressed by incorporating polyethylenimide (PEI) functionalized rGO with Ce-MOF-on-Fe-MOF and Fe-MOF-on-Ce-MOF nanomaterials. Simultaneously, toluidine blue (Tb) was employed as a redox probe and physically adsorbed onto the synthesized materials, resulting in the formation of two nanomaterials: rGO@Ce-MOF-on-Fe-MOF@Tb and rGO@Fe-MOF-on-Ce-MOF@Tb. The fundamental characterization reveals that the sensing performance of the rGO@Ce-MOF-on-Fe-MOF@TB-based immune sensor surpasses that of the rGO@Fe-MOF-on-Ce-MOF@TB-based immune sensor, which is attributed to the fact that, unlike the interlayer-constrained structure of Fe-MOF-on-Ce-MOF, in Ce-MOF-on-Fe-MOF, Ce-MOF penetrates into Fe-MOF to form a heterogeneous structure due to the relatively large pore size of Fe-MOF, which better combines the excellent biocompatibility and strong anchoring effect of Fe MOFs on antibodies, as well as the high electrochemical activity and conductivity of Ce-MOF, to enhance sensing performance. The proposed label-free immunosensor based on rGO@Ce-MOF-on-Fe-MOF@Tb has a wide linear range (1-100 000 mU mL-1), a low detection limit (0.34 mU mL-1), good stability, reproducibility, and repeatability, and satisfactory applicability, which provides a potential platform for clinical applications.