Bimetallic Metal Research Articles

Catalytic activities modulated by flexible bimetallic metal–organic frameworks

Structural modulation of the flexible MIL-88B(Fe/Co) leads to the tunable oxygen evolution reaction.

Rational synthesis of bimetallic CoFe-MOF-74 grown on Ni foam converted into bamboo-shoot-like α-Co(OH)2/CoFe2O4 nanorods for high-performance supercapacitors

Owing to the high specific surface area, rich active sites, well-controlled morphology and structural stability with tunable compositional components, the rational combination of hybrid nanostructured materials from metal-organic frameworks templates has become highly attractive and still of great challenge for supercapacitors. In this work, three bimetallic metal–organic frameworks Co1-xFex-MOF-74/NF (x = 0.25, 0.5 and 0.75) nanoarrays with different proportional Co/Fe ratios on nickel foam have been successfully designed and fabricated via in-situ interfacial growth method, which were further controllable converted to α-Co(OH)2/CoFe2O4 nanoarrays with different proportional Co/Fe ratios CF-x/NF (x = 0.25, 0.5 and 0.75) without structure collapse through alkaline etching process. Among them, the transformation of the bamboo-shoot-like CF-0.75/NF electrode displays excellent electrochemical properties with high area capacitance (3941.14 mF/cm2 at 2 mA/cm2), good rate capability, low resistances and remarkable cycling stability. The CF-0.75//AC ASC device delivers a high energy density of 0.16 mWh/cm2 at a power density of 0.756.1 mW/cm2. And this CF-0.75//AC ASC device exhibits a good cycling stability and practical application in energy storage field. This strategy could be extend to form other unique bimetallic hybrids nanoarrays architectures with enhanced electrochemical activity for high-performance energy storage devices.

Bimetallic metal–organic frameworks-based ratiometric fluorescence sensor for the quantitative detection of thiram in fruits samples

The identification of residual thiram (Tr) in foods is vital in view of its harmful effects on human health. Herein, a ratiometric fluorescence sensor (I435/I590) based on rhodamine B/NH2-MIL-53(Al0.75Fe0.25) was constructed for the detection of Tr. Interestingly, the probe RhB/NH2-MIL-53(Bim) assisted by Cu2+ could rapidly and sensitively recognize Tr with a low detection limit of 0.11 μg/mL in 10 min. The fluorescence sensing mechanism was investigated using fluorescence spectra, UV–Vis absorption spectra, the fluorescence lifetime and quantum yield. The results showed that the excellent sensing performance was attributed to fluorescence resonance energy transfer, electrostatic interaction, and photoinduced electron transfer. In addition, the practical application of this platform showed acceptable relative recoveries for Tr (84.03–107.81 %), and precisions were also achieved (relative standard deviation ≤ 8.69 %, n = 3). These results show that the presented herein can be applied to monitor the Tr content in real fruit samples.

Synthesis of spindle-like amino-modified Zn/Fe bimetallic metal-organic frameworks as sorbents for dispersive solid-phase extraction and preconcentration of phytohormoes in vegetable samples

Amino-modified Zn/Fe bimetallic metal–organic frameworks (NH2-Zn/Fe-MIL-88) were synthesized using a one-step solvothermal method with FeCl3·6H2O and Zn(NO3)2·6H2O as metal salts and 2-aminoterephthalic acid as organic ligand. The morphology of NH2-Zn/Fe-MIL-88 can be regulated from octahedral-like to spindle-like with changing molar ratios of metal salts. Using NH2-Zn/Fe-MIL-88 as sorbent, a dispersive solid-phase extraction with putting sorbents into sample solution to extract targets was developed to preconcentrate phytohormones in vegetables. To study the extraction efficiency, a series of NH2-Zn/Fe-MIL-88s with varying molar ratios of metal salts were prepared. The results indicated that NH2-Zn/Fe-MIL-88(1) presented the highest extraction efficiency (82.6 %–98.1 %) to phytohormones among all prepared NH2-Zn/Fe-MIL-88(x). The limits of detection were calculated at 0.07–0.15 ng/mL. The adsorption isotherms and kinetic parameters of NH2-Zn/Fe-MIL-88 for phytohormones were conformed to Langmuir and pseudo-second-order models. The NH2-Zn/Fe-MIL-88 as sorbent combined with HPLC was applied to detect phytohormones in cucumber and tomato samples.

Nickel–cobalt layered double hydroxide/NiCo2S4/g-C3N4 nanohybrid for high performance asymmetric supercapacitor

Graphitic carbon nitride (g-C3N4) with semiconducting nature can be considered for energy storage system by modifying its electrical conductivity and structural properties through formation of hybrid with materials such as bimetallic metal sulfide and nickel-cobalt layered double hydroxide (LDH). g-C3N4 as a N-rich compound with basic surface sites can change the surface properties of nanohybrid and impress the charge transfer. In this study, a nanohybrid based on nickel-cobalt LDH and sulfide and graphitic carbon nitride (NiCo LDH/NiCo2S4/g-C3N4) was synthesized through a three-step method. At first, Ni doped ZIF-67 was formed at the surface of g-C3N4 nanosheets and then the product was calcined in a furnace to form NiCo2O4/g-C3N4. At next step, the sample was hydrothermally converted to NiCo2S4/g-C3N4 using thioacetamide and finally modified with NiCo LDH nanoplates to form porous structure with high surface area. The NiCo LDH/NiCo2S4/g-C3N4 nanohybrid showed high specific capacitance of 1610 F g−1 at current density of 1 A g−1 and also excellent stability of 108.8% after 5000 cycles at potential scan rate of 50 mV s−1, which makes it promising candidate for energy storage. An asymmetric system was prepared using nickel foams modified with NiCo LDH/NiCo2S4/g-C3N4 and g-C3N4 as positive and negative electrodes, respectively. The specific capacitance of 246.0 F g−1 was obtained at 1 A g−1 in 6 M KOH solution and system maintained 90.8% cyclic stability after 5000 cycles at potential scan rate of 50 mV s−1. The maximum energy density and power density of the system were calculated as 82.0 Wh kg−1 and 12,000 W kg−1, respectively, which demonstrate its capability for energy storage.

Microneedle-Assisted Transdermal Delivery of 2D Bimetallic Metal-Organic Framework Nanosheet-Based Cascade Biocatalysts for Enhanced Catalytic Therapy of Melanoma.

Current conventional treatments for malignant melanoma still face limitations, especially low therapeutic efficacy and serious side effects, and more effective strategies are urgently needed to develop them. Delivering biocatalysts into tumors to efficiently trigger in situ cascade reactions has shown huge potential in producing more therapeutic species or generating stronger tumoricidal effects for augmented tumor therapy. Recently, ultrathin 2D metal-organic framework (MOF) nanosheets have acquired great interest in biocatalysis owing to their large surface areas and abundant accessible active catalytic sites. Herein, an enhanced catalytic therapeutic strategy against melanoma is developed by biocompatible microneedle (MN)-assisted transdermal delivery of a 2D bimetallic MOF nanosheet-based cascade biocatalyst (Cu-TCPP(Fe)@GOD). Profiting from the constructed dissolving MN system, the loaded Cu-TCPP(Fe)@GOD hybrid nanosheets can be accurately delivered into the melanoma sites through skin barriers, and subsequently, trigger the specific cascade catalytic reactions in response to the acidic tumor microenvironment to effectively generate highly toxic hydroxyl radical (• OH) and deplete glucose nutrient for inducing the death of melanoma cells. The ultimate results prove the high melanoma inhibition effect and biosafety of such therapeutic modality, exhibiting a new and promising strategy to conquer malignant melanoma.

Bimetallic metal–organic framework derived Mn, N co-doped Co-Carbon for electrochemical detection of nitrite

Bimetallic metal–organic framework derived Mn, N co-doped Co-Carbon for electrochemical detection of nitrite

Bimetallic CuSbSe2 : A Potential Anode Material for Sodium and Lithium-Ion Batteries with High-Rate Capability and Long-Term Stability.

Bimetallic transition metal chalcogenides (TMCs) materials have emerged as attractive anodes for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) because of the high intrinsic electronic conductivity, rich redox sites and unique reaction mechanism. In this work, we report the synthesis and electrochemical properties of a novel bimetallic TMCs material CuSbSe2 . The as-prepared anode delivers a high reversible capacity of 545.6 mA h g-1 for SIBs and 592.6 mA h g-1 for LIBs at a current density of 0.2 A g-1 , and an excellent rate capability of 425.9 mA h g-1 at 20 A g-1 for SIBs and 226.0 mA h g-1 at 10 A g-1 for LIBs without any common-used surface modification or carbonaceous compositing. In addition, ex situ X-ray diffraction (XRD) and High-resolution transmission electron microscopy (HRTEM) reveal a combined conversion-alloying reaction mechanism of LIBs and NIBs. Our findings suggest bimetallic CuSbSe2 could be a potential anode material for both SIBs and LIBs.

Kinetic and Thermodynamic Insights into Advanced Energy Storage Mechanisms of Battery-Type Bimetallic Metal–Organic Frameworks

The engineering of high-performance battery-type electrode materials highly depends on the guidance from the combination of experimental analysis and theoretical simulation. Herein, the joint experimental–theoretical investigation provides a mechanistic explanation for the electrochemical performance enhancement in bimetallic metal–organic frameworks (MOFs). The superior CoNi-MOF in our study exhibits advanced electrochemical energy storage performance, achieving a high specific capacity of 382 C g–1 (1 A g–1), 2.0 and 1.4 times that of Co-MOF and Ni-MOF, respectively. Such a significant enhancement results from the surface-controlled reaction kinetics and the low onset potential contributed by the well-tuned electronic structures of bimetallic MOFs. Our study opens up new perspectives for understanding the advantages of mixed metal sites in MOFs for electrochemical energy storage.

Freestanding Cactus-Like Dual-Phase Bimetallic Metal–Organic Framework as a High-Efficiency Electrocatalyst for Water Oxidation

Realizing a high-efficiency electrochemical oxygen evolution reaction (OER) is a great challenge in water splitting and metal–air battery fields due to the slow reaction kinetics. Herein, a synchronous dual-phase synthetic strategy is developed to successfully construct a cactus-like dual-phase bimetallic metal–organic framework (MOF) on a nickel foam (NF) substrate (noted as NiFe-MOF@NF). It is constituted by Ni-main NiFe-MOF and Fe-main NiFe-MOF. When functioning as an anode, the freestanding cactus-like dual-phase NiFe-MOF@NF catalyst merely requires a lower overpotential of 277 mV to supply 100 mA cm–2 with robust stability (90% retainment of initial current density after 24 h chronoamperometry measurement). Density functional theory calculations on the NiFe-MOF@NF catalyst reveal that the combination of Ni and Fe has efficiently modulated the electron configuration of metal centers and optimized the absorption/desorption of OER oxygen-containing intermediates. Thus, we demonstrate a novel synchronous dual-phase synthetic strategy to engineer freestanding dual-phase electrocatalysts, which feature multiple synergetic effects considerably boosting OER performance for optimizing the energy conversion and storage system.

Binary transition metal doping to create efficient TM–N–C electrocatalysts and enhance ORR catalysis under an external magnetic field

A family of bimetallic oxygen reduction catalysts was prepared from N-containing porous synthetic polymers doped with iron chloride and with the chloride of either Cr, Mn, Co, Cu or Zn. The effects of Fe interaction with the additional transition metal and their magnetic characteristics on the catalytic activity in the oxygen reduction reaction (ORR) in alkaline medium were investigated. In addition, the ORR catalyzed by these bimetallic non-precious metal catalysts was studied under an external magnetic field generated by a permanent magnet. Linear sweep voltammetry in stationary conditions showed that the Co co-doped catalysts exhibit the highest activity, strongly enhanced by an external magnetic field applied at a 90° angle relative to the catalyst layer surface. Rotating ring-disk electrode tests (at pH = 13) showed that catalysts co-doped with either Mn or Zn exhibit the highest catalytic activity. In these instances, an external magnetic field decreases the amount of undesirable peroxide intermediate as it increases the number of electrons transferred for ORR.

Amorphous Bimetallic Metal–Organic Frameworks with an Optimized D-Band Center Enable Accelerating Oxygen Evolution Reaction

Amorphous Bimetallic Metal–Organic Frameworks with an Optimized D-Band Center Enable Accelerating Oxygen Evolution Reaction

Iron cobalt-doped carbon nanofibers anode to simultaneously boost bioelectrocatalysis and direct electron transfer in microbial fuel cells: Characterization, performance, and mechanism

A self-supporting electrode (FeCo-MOF/CNFs) combining iron cobalt bimetallic metal–organic frameworks (FeCo-MOFs) with carbon nanofibers (CNFs) was applied as the anode of a microbial fuel cell (MFC). The introduction of FeCo-MOFs enhanced graphitization degree and electrical conductivity, which endowed FeCo-MOF/CNFs with excellent electrocatalytic performance and good biocompatibility. The hierarchical porous structure of FeCo-MOF/CNFs provided abundant attachment sites for electroactive bacteria (EAB) and facilitated rapid electron transfer. The MFC equipped with FeCo-MOF/CNFs anode (FeCo/CNFs-MFC) exhibited considerable power generation output (maximum power density: 5.3 ± 0.2 W/m2, coulombic efficiency: 54 ± 4 %). In addition, FeCo/CNFs-MFC achieved a direct electron transfer (DET) catalytic current density of 0.63 A/m2. FeCo-MOF/CNFs could simultaneously enhance the bioelectrocatalysis activity and promote the DET process of EAB, which provided an effective way to improve the sluggish extracellular electron transport process of the MFC anode.

Enhanced NO2 Sensing Performance of ZnO-SnO2 Heterojunction Derived from Metal-Organic Frameworks.

Nitrogen dioxide (NO2) is the major reason for acid rain and respiratory illness in humans. Therefore, rapid, portable, and effective detection of NO2 is essential. Herein, a novel and simple method to construct a ZnO-SnO2 heterojunction is fabricated by pyrolysis of bimetallic metal organic frameworks. The sensitivity of ZnO-SnO2 heterojunction towards 0.2 ppm NO2 under 180 °C is 37, which is 3 times that of pure ZnO and SnO2. The construction of heterojunction speeds up the response-recovery process, and this kind of material exhibits lower detection limit. The construction of heterojunction can significantly improve the NO2 sensitivity. The selectivity, stability, and moisture resistance of ZnO-SnO2 heterojunction are carried out. This could enable the realization of highly selective and sensitive portable detection of NO2.

Construction of conducting bimetallic organic metal chalcogenides via selective metal metathesis and oxidation transformation

Conducting organic metal chalcogenides (OMCs) have attracted considerable interest for their superior electrical properties and fascinating functions. However, the electronic structural and functional regulation of OMCs are typically limited to the combination of monometallic nodes and graphene-like ligands. Here, we report a family of bimetallic OMCs ([CuAgx(C6S6)]n, x = 4 or 2) synthesized via selective metal metathesis and oxidation transformation. Both OMCs have alternatively stacked one-dimensional (1D) copper-dithiolene chains and 2D Ag-S networks, which can synergistically serve as charge transport pathways, rendering these bimetallic materials highly conductive. The incorporation of heterometallic nodes turned nonmagnetic [Ag5(C6S6)]n into paramagnetic metallic [CuAg4(C6S6)]n, which exhibited a coherence-incoherence crossover in magnetic susceptibility measurements and an unusually large Sommerfeld coefficient, reminiscent of the characteristics of Kondo lattice. This work opens up an avenue for tailoring the electronic structures of OMCs and provides a platform for studying the dichotomy between electronic localization and itinerancy.

Solvent-free synthesis of NiCo2S4 having the metallic nature.

Nickel-cobalt sulfide (NiCo2S4) is a prominent member of bimetallic transition metal sulfides. It is being widely used for a variety of applications such as electrode material, photocatalysis, and energy storage devices (like pseudo capacitors, supercapacitors, solar cells, and fuel cells) due to its better electronic conductivity, manageable morphology, and high capacitance. This work presents the one-step solventless synthesis of NiCo2S4 sheet-like nanostructures and then explores their metallic nature. Scanning electron microscopy (SEM) and transmission electron microscopic (TEM) analysis show the sheet-like grown morphology. Few nanorods are also seen. Except for a recent study (Xia et al. 2015) that shows metallic behavior, most of the reports show that NiCo2S4 is a semiconductor with claimed bandgap between 1.21 and 2.4eV. In this study, we observe from UV-Vis and diffuse reflectance spectroscopy (DRS) that NiCo2S4 has a specific band gap value between 2.02 and 2.17eV. However, IV characteristics in the temperature range of 300-400K show that NiCo2S4 is a metal with a positive temperature coefficient of resistance consistent with a recent report. Furthermore, we see the ohmic conduction mechanism. The Arrhenius plot is drawn, and the activation energy is calculated to be 3.45meV. The metallic nature is attributed to the coupling of two metal species (nickel and cobalt), which accounts for its superior conductivity and performance in a variety of essential applications.

Au Nanoparticles in 2D Bimetallic Metal–Organic Frameworks with Enhanced Plasmonic Nanozyme Activity for Antibacterial Therapy

Au Nanoparticles in 2D Bimetallic Metal–Organic Frameworks with Enhanced Plasmonic Nanozyme Activity for Antibacterial Therapy

The application of Bimetallic metal–organic frameworks for antibiotics adsorption

Fe/Zr-base metal–organic frameworks(Fe/Zr-MOFs) were prepared using a solvothermal method from 1,3,5-phthalic acid (H3BTC, 98 %) as the organic chain and ferrous heptahydrate (FeSO4·7H2O) andzirconium acetate Zr(CH3COO)4] as the metal ions. The resulting material was used to remove Doxycycline hydrochloride (DC).The experimentalresultsshowedthat when the concentration of DC was 10 ppm and the mass of Zr/Fe-MOFs was 100 mg, the maximum removal rate after 5 h was 87.5 %. The results showed that the correlation coefficients (R2) of the pseudo-second-order kinetics model and Freundlich isotherm model of Zr/Fe-MOFs adsorption of DC were greater than 0.99, indicating good consistency.The results showed that the adsorption process of DC by Zr/Fe-MOFs was endothermic and spontaneous. Fe/Zr-MOFs had a high adsorption capacity for DC removal and good application prospects.

Controllable synthesis of FeMn bimetallic ferrocene-based metal-organic frameworks to boost the catalytic efficiency for removal of organic pollutants.

A series of FeMn bimetallic ferrocene-based metal-organic frameworks (FeMn-Fc-MOFs) with various molar ratios of Fe and Mn (1:9, 2:8, 4:6, 6:4) were successfully synthesized using a simple hydrothermal synthesis method and employed as an efficient activator on persulfate (PS) activation for water decontamination. Characterizations demonstrated that Fe and Mn were smoothly introduced into ferrocene-based MOFs and various molar ratios of Fe:Mn had some influence on crystallinity and surface structure of FeMn-Fc-MOFs. Within 120min, Fe4Mn6-Fc-MOFs demonstrated the best catalytic activity among the different molar ratios, and acid orange 7(AO7) degradation rate was up to 92.0%. In addition, electrochemical experiments revealed that Fe4Mn6-Fc-MOFs possessed superior electron transfer capability than other FeMn-Fc-MOFs, leading to better catalytic performance. Moreover, quenching tests and electron paramagnetic resonance (EPR) detection indicated that hydroxyl radicals and sulfate radicals were both responsible for AO7 decomposition. Notably, the redox cycle of Fe(II)/Fe(III) and Mn(II)/Mn(IV) was discovered in the Fe4Mn6-Fc-MOFs/PS system, which was considered as the limiting process for the cleavage of the O-O bond in PS to generate active radicals. Ultimately, the Fe4Mn6-Fc-MOFs exhibits an excellent universality and good cycling stability for 5 continuous runs. This paper broadens the application of ferrocene-based MOFs on heterogeneous PS activation in environmental catalysis.

Structural and Electronic Modulation of Iron-Based Bimetallic Metal-Organic Framework Bifunctional Electrocatalysts for Efficient Overall Water Splitting in Alkaline and Seawater Environment.

Metal-organic frameworks (MOFs) are considered potential electrocatalysts for efficient water splitting. However, the structure-activity relationship of most MOFs is not systematically analyzed for electrocatalysis for anodes and cathodes. In this paper, we provide a strategy to modulate the electronic microstructure of iron-based bimetallic MOFs (MFe-BDC (M: Mg, Zn, Cd)) grown on the nickel foam (NF) as bifunctional electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The optimal bimetallic CdFe-BDC via modulating appropriate metal cations of IIA and IIB possesses excellent OER and HER performance with the lowest overpotentials of 290 mV at 100 mA cm-2 and 148 mV at 10 mA cm-2, respectively. The overall water splitting performance of the as-prepared CdFe-BDC requires 1.68 V to achieve a current density of 10 mA cm-2 in the real seawater media, and it exhibits the competitive H2 and O2 production rates of 6.4 and 3.1 μL s-1, respectively, in ambient alkaline conditions, suggesting its potential practical applications. Density functional theory (DFT) calculations demonstrate the relationship between microstructure and electrocatalytic performance of bimetallic MFe-BDC. This work emphasizes the significance of tailoring the electronic microstructure of bimetallic MOFs for efficient overall water splitting in alkaline and seawater environment.