Bimetallic Imidazolate Framework Research Articles

Construction of hierarchical ZnS/MoS2 bimetallic sulfides heterostructures for high – performance sodium ion batteries

The rational design and construction of bimetallic hierarchical nanostructures are effective strategies for the development of conversion alloying reaction anode for sodium ion batteries (SIBs). Herein, novel hierarchical ZnS/MoS2 bimetallic sulfides are designed and fabricated via a simple sulfuration process, in which ZnS/MoS2 nanoparticles are encapsulated in Zn/Mo bimetallic imidazolate framework (Zn/Mo BIFs) derived nitrogen doped carbon frameworks with covering reduced graphene oxide (ZnS@MoS2/NC@rGO). The derived nitrogen doped carbon and graphene nanosheets can enhance electrical conductivity, and accommodate volume changes of ZnS/MoS2 on the cycling. Meanwhile, the ZnS-MoS2 heterostructure accelerates diffusion dynamics in the interface, and promotes the charge transfer rate. Due to the compositional and structural features, the obtained ZnS@MoS2/NC@rGO sample delivers superior sodium storage performance, which achieves a specific capacity of 480 mAh/g at 0.2 A/g over 100 cycles, and good rate capability of 308 mAh/g at 4 A/g. The full SIBs are fabricated by ZnS@MoS2/NC@rGO anode with homemade Na3V2(PO4)3/C cathode which exhibit the high energy density of 127.8 Wh kg−1 at the power density of 105.9 W kg−1. The preparation strategy manifests an effective and simple method to in situ fabricate hierarchical hetero-interfaces bimetallic sulfides/carbon anode materials for SIBs.

Design of ZIF-67 MOF-derived Co3O4/NiCo2O4 nanosheets for supercapacitor electrode materials

Binary transition metal oxides exhibit improved properties including good redox potentials and electrical conductivities compared with single metal oxides as electrode materials in energy storage. Herein, ZIF-67 is prepared by a one-step method using Co2+ as the central metal ion, 2-methylimidazole as the organic ligand, and methanol as an organic solvent at room temperature. Hollow NiCo2O4 and sheet-like Co3O4/NiCo2O4 derived from bimetallic imidazolate framework precursors were synthesized by adding cobalt and nickel ions in appropriate proportions. A hollow and porous structure is achieved for the reaction between a nickel salt and ZIF-67, and this unique nanostructure provides a high active surface area, which is beneficial to the electrochemical properties. Several samples are prepared and used as electrode materials for electrochemical tests in 6 M KOH. As a result, the Co3O4/NiCo2O4 electrode with a sheet nanostructure showed a high specific capacitance of 846 F g−1 at a current density of 0.5 A g−1. This Co3O4/NiCo2O4 electrode material is promising for future studies on high-performance supercapacitors to solve emerging energy-related problems. [Formula: see text]

Boosting Faradic efficiency of dinitrogen reduction on the negatively charged Mo sites modulated via interstitial Fe doping into a Mo2C nanowall catalyst

The electrochemical nitrogen reduction reaction (eNRR) provides a sustainable way to generate ammonia (NH3) but its Faradaic efficiency (FE) is relatively low and could be further improved, especially on the highly active molybdenum carbide (Mo2C) electrocatalyst. Our theoretical calculations suggest that unlike substitute doping model, interstitial Fe doping into Mo2C is highly eNRR-selective due to decreasing hydrogen evolution activity and unique surface-hydrogenation mechanism on negatively charged Mo sites around Fe atoms. Inspired by this prediction, we successfully developed a novel interstitial Fe doped Mo2C electrocatalyst by the pyrolysis of Fe-doped Mo/Zn bimetallic imidazolate frameworks (Fe-Mo/Zn BIFs) as a precursor where Fe atoms substitute Zn sites to obtain the spatial confinement effect. When evaluated in eNRR catalysis, Fe/Mo2C catalyst therefore exhibits a much higher FE of 20.1% at −0.45 V vs. RHE (reversible hydrogen electrode), which is almost double that of pristine Mo2C and substitute type. Moreover, the Fe/Mo2C catalyst also exhibits high ammonia yield rate with excellent durability over the six continuous cycles.

Room temperature and aqueous synthesis of bimetallic ZIF derived CoNi layered double hydroxides and their applications in asymmetric supercapacitors

Single imidazolate framework-67 (ZIF-67) is commonly used as a template to prepare layered double hydroxides (LDHs) with specific morphology to improve the performance of materials. Herein, the Co2+ ion in ZIF-67 is partially substituted by Ni2+ to obtain the dodecahedron bimetallic imidazolate framework (CoNi-ZIF). Subsequently, using bimetallic CoNi-ZIF as the sacrificial template, CoNi-LDH hierarchical hollow cage structures with wrinkled nanosheet arrays are synthesized at room temperature and in aqueous solution by an inexpensive and environment friendly surfactant-free approach. The optimized etched CoNi-LDH4 has a maximum specific capacitance of 1877 F g−1 at a current density of 1 A g−1, and cycling stability of 99.89% after 5000 cycles, which is significantly better than that of ZIF-67 derived CoNi-LDH67 (1357 F g−1 at 1 A g−1, cycling stability of 73.35%). The asymmetric supercapacitor with CoNi-LDH4 as a cathode and activated carbon (AC) as anode has an energy density of 49.3 Wh kg−1 at 750 W kg−1 power output and stable cycling performance (capacity retention of 92.13% after 5000 cycles). This study shows the prospect of bimetallic CoNi-ZIF derived LDHs nanostructures prepared at room temperature and in aqueous solution to improve the performance and stability of supercapacitors.

Tuning d-band center of tungsten carbide via Mo doping for efficient hydrogen evolution and Zn–H2O cell over a wide pH range

Abstract Designing highly active transition metal carbides based electrocatalysts to substitute for the state-of-the-art noble-metal materials for hydrogen evolution reaction (HER) over a wide pH range is still a crucial challenge. Herein, we reported a novel 2D hybrid electrocatalyst containing Mo-doped WC core with particle size of ~5 nm embedded into N-doped carbon shells (Mo-WC@NCS) through a carbonization treatment of Mo-doped W/Zn bimetallic-imidazolate frameworks. Benefiting from large surface area and optimized electronic structure, the achieved Mo-WC@NCS hybrid displayed a low overpotential of 179 mV at 10 mA cm−2 with a small Tafel slope of 81 mV dec−1 for HER in base, showing almost the best performance among all previously reported WC-based hybrid HER electrocatalysts. This Mo-WC@NCS hybrid also delivered robust HER catalytic activities in both acidic and neutral media. Experimental observations and theoretical calculations demonstrated that the d-band center of W in Mo-WC@NCS hybrid was obviously downshifted after Mo dopants, which was beneficial to modulate the electronic structure of the W centers and thereby facilitated the H desorption, thus boosting hydrogen generation. Acting as a cathode in alkaline-acid Zn–H2O fuel cell, the Mo-WC@NCS hybrid delivered a power density of up to 41.4 mW cm−2 and maintained a long-term stability for H2 generation.

Mesoporous copper zinc bimetallic imidazolate MOF as nanofiller to improve gas separation performance of PEBA-based membranes

CO2-philic copper zinc bimetallic imidazolate framework (CuZnIF) particles were synthesized and introduced into poly (ether block amide) (PEBA) matrix in the range of 0.1–10 wt.% to fabricate mixed matrix membranes (MMMs) with enhanced performance for CO2 separation. The effects of nanoparticle loading and feed pressure on the separation performance of the MMMs were investigated. The CuZnIF particles were characterized by FTIR, FESEM, XRD, BJH and BET tests. The nanocomposite membrane containing 0.5 wt.% of CuZnIF showed the best performance; CO2 permeability, CO2/N2 and CO2/CH4 selectivity of MMMs were improved about 47, 61 and 30%, respectively.

Rational Design of Holey 2D Nonlayered Transition Metal Carbide/Nitride Heterostructure Nanosheets for Highly Efficient Water Oxidation

AbstractDue to integrated advantages in electrochemical functionalities for energy conversion, 2D nonlayered heterostructure nanosheets offer new and fascinating opportunities for electrocatalysis but their fabrication is challenging when compared with the widely studied 2D layered heterostructure. Herein, a bottom‐up approach is established for facile synthesis of holey 2D transition metal carbide/nitride heterostructure nanosheets (h‐TMCN) with regulated hole sizes by controlled thermal annealing of the Mo/Zn bimetallic imidazolate frameworks (Mo/Zn BIFs). Ex situ phase and structural identifications disclose that the Mo/Zn BIFs precursor experiences interconnected three steps of transformation to produce h‐TMCN. Especially, the slow successive solid‐state diffusion of nitrogen and carbon into immediate noncrystalline molybdenum oxides allows the intergrowth of Mo2C and Mo2N into the 2D nonlayered heterostructure. X‐ray fine structure analysis coupled with high resolution X‐ray photoelectron spectroscopy demonstrate that Mo2C and Mo2N in the microdomains can chemically bond with each other, producing the abundant active N–Mo–C interfaces toward water splitting. Consequently, h‐TMCN affords low overpotentials, high turnover frequencies, rapid charge transfer, and superior long‐term stability toward electrocatalytic water oxidation. The present work demonstrates the feasibility of developing a broad range of 2D nonlayered heterostructures for high efficiency chemical energy conversion.

Hierarchical tri-functional electrocatalysts derived from bimetallic–imidazolate framework for overall water splitting and rechargeable zinc–air batteries

Due to the hierarchical structure resulting from the transformation to the bimetallic–imidazolate framework, this catalyst electrode has a benchmarking tri-functional catalytic activity.

2D carbide nanomeshes and their assembling into 3D microflowers for efficient water splitting

Herein, we have developed a facile process of synthesizing N and O surface-terminated 2D molybdenum carbide nanomeshes (Mo2CTx NMs) and assembling them into 3D microflowers (Mo2CTx MFs) by one-step pyrolysis of Mo/Zn bimetallic imidazolate frameworks. When used as an oxygen evolution reaction (OER) catalyst, the Mo2CTx NMs thus derived exhibit outstanding catalytic activity with an overpotential of 180 mV at the current density of 10 mA cm−2. This enables Mo2CTx NMs to become one of the best OER electrocatalysts ever reported, with the desired stability in alkaline environment which is a major challenge for most of the non-oxide/hydroxide based electrocatalyts. Additionally, the Mo2CTx MFs can catalyze the hydrogen evolution reaction (HER) and act as bifunctional electrocatalysts for overall water splitting which can attain a current density of 10 mA cm−2 at 1.7 V. Mo LIII-edge X-ray near-edge absorption studies combined with theoretical calculations imply that surface-terminated oxygen is crucial in activating the outstanding OER performance, whereas the top Mo atomic sites on the surface contribute to excellent HER performance.

Construction of Ni-Co-Mn layered double hydroxide nanoflakes assembled hollow nanocages from bimetallic imidazolate frameworks for supercapacitors

Layered double hydroxides (LDHs) with 3-dimentional (3D) hollow nanoarchitetures are highly desirable for energy related applications. In this study, Ni-Co-Mn LDH nanoflakes assembled hollow nanocages are constructed from bimetallic imidazolate framworks precursors. Benefiting from the 3D hierarchical porous strcuture and composition, the as-synthesized ternary Ni-Co-Mn LDH hollow nanocage, as a electrode for supercapacitor, demonstrates a remarkable electrochemical performance with a high specific capacitance of 2012.5 F g−1 at 1 A g−1 and a good rate capacity of 75.0% retention at 10 A g−1, significantly outperforming binary Ni-Co LDH (1266.2 F g−1 at 1 A g−1, 41.8% retention at 10 A g−1). This work demonstrates the construction of 3D hollow nanostructured LDH with multicomponent compositions for the first time, and can be simply extended to construct other hollow structured electrode materials for energy storage devices.

Acid-Catalyzed Synthesis and CO<SUB>2</SUB> Adsorption of Cu and Cu-Zn Bimetallic Imidazolate Frameworks

Acid-Catalyzed Synthesis and CO<SUB>2</SUB> Adsorption of Cu and Cu-Zn Bimetallic Imidazolate Frameworks

Synthesis of copper–zinc bimetallic imidazolate framework compounds and the structure of Cu(I)-containing Cu 2Zn(N 2C 3H 3) 4

Copper(II)–zinc(II) bimetallic imidazolate metal–organic framework compounds of composition Cu a Zn b Im 2( a + b ) (Im = C 3H 3N 2), including Cu 2ZnIm 6 ( 1), were prepared in high yields from the metal oxides under mild aqueous conditions using a novel acid catalysis method. Mild acidic hydrothermal treatment of paramagnetic 1 (≥120 °C) gave diamagnetic Cu(I)-containing Cu 2ZnIm 4 ( 2) in high yield. The formation mechanism of 2 involves electron transfer from Im − to Cu(II), with concomitant formation of the unusual cyclotriimidazole, C 9H 6N 6. Air-stable 2, characterized by single-crystal X-ray diffraction, crystallized in the tetragonal space group P 4 ¯ 2 1 c , with a = b = 10.9623(3), c = 6.3231(4) Å, α = β = γ = 90°, V = 759.86(6) Å 3, and Z = 1.

Acid-catalyzed synthesis of zinc imidazolates and related bimetallic metal-organic framework compounds

A convenient method involving acid catalysis is described for the preparation of zinc imidazolate metal organic framework compounds of the type ZnIm2 (Im = imidazolate, 1,3-N2C3H3) and C-substituted derivatives, including 2-Me-, 2-Et- and benzimidazolates. This method also applies to synthesis of analogous copper and cobalt imidazolates, copper–zinc bimetallic imidazolates, (Cu a Zn b Im2(a+b)), heterometal-doped zinc imidazolates (M x Zn(1−x)Im2), and multimetallic imidazolates. An unusual copper(1)-containing crystalline bimetallic imidazolate framework compound Cu2ZnIm4 was prepared in high yield and structurally characterized . Crystal structure redeterminations were also made for tetragonal zinc imidazolate framework solid and monomeric zinc diimidazole diacetate.