MOF-based Materials Research Articles

Recent advances in luminescent metal-organic frameworks and their photonic applications.

In recent years, metal-organic frameworks (MOFs) have been attracting ever more interest owing to their fascinating structures and widespread applications. Among the optoelectronic materials, luminescent MOFs (LMOFs) have become one of the most attractive candidates in the fields of optics and photonics thanks to the unique characteristics of their frameworks. Luminescence from MOFs can originate from either the frameworks, mainly including organic linkers and metal ions, or the encapsulated guests, such as dyes, perovskites, and carbon dots. Here, we systematically review the recent progress in LMOFs, with an emphasis on the relationships between their structures and emission behaviour. On this basis, we comprehensively discuss the research progress and applications of multicolour emission from homogeneous and heterogeneous structures, host-guest hybrid lasers, and pure MOF lasers based on optically excited LMOFs in the field of micro/nanophotonics. We also highlight recent developments in other types of luminescence, such as electroluminescence and chemiluminescence, from LMOFs. Future perspectives and challenges for LMOFs are provided to give an outlook of this emerging field. We anticipate that this article will promote the development of MOF-based functional materials with desired performance towards robust optoelectronic applications.

MOF/COF-based materials using 3D printing technology: applications in water treatment, gas removal, biomedical, and electronic industries

We have considered the newest outcomes in the uses of 3D-printed COF- and MOF-based materials for diverse applications.

Metal–organic framework-based materials for full cell systems: a review

Applications of MOF-based materials in advanced full cell systems of lithium batteries, sodium batteries, aqueous batteries, fuel cells and other secondary batteries.

Metal–organic framework-based materials: advances, exploits, and challenges in promoting post Li-ion battery technologies

In this review, the development of MOFs and MOF-based materials for application in non-Li rechargeable batteries has been highlighted together with describing the various persisting challenges and their corresponding remedies for these materials.

Metal-organic frameworks as photoluminescent biosensing platforms: mechanisms and applications.

Biosensing is of vital importance for advancing public health through monitoring abnormalities in biological systems, which may be potentially associated with certain body dysfunctions. A wide range of luminescent materials have been actively pursued in the fabrication of biosensing platforms, particularly ones that can function in complex biological fluids with high selectivity and sensitivity. Recently, metal-organic frameworks (MOFs) have experienced rapid growth due to their tunable structures, large surface area, and being prone to surface engineering, etc. These virtues endow MOF materials with immense feasibility in the target-oriented construction of sensing platforms for specific applications. In this review, we extrapolated six sensing mechanisms for MOF-based photoluminescent biosensing platforms, including photoelectron transfer (PET), resonance energy transfer (RET), competition absorption (CA), structural transformation (ST), chemical conversion (CC), and quencher detachment (QD). Accordingly, recent progress of MOF-based materials in photoluminescence sensing of biomolecules, biomarkers, drugs, and toxins was highlighted. The objective of this review is to provide readers with an extensive overview of the design and synthesis of MOF materials for photoluminescence biosensing. The challenges and outlook are briefly discussed at the end.

Fabrication of Fe3O4/CuO@C composite from MOF-based materials as an efficient and magnetically separable photocatalyst for degradation of ciprofloxacin antibiotic

In this work, a novel ternary Fe3O4/CuO@C composite was fabricated using iron-doped copper 1,4-benzenedicarboxylate metal-organic frameworks as a self-sacrificing template. The morphological, structural, and optical properties of the prepared composite were determined by various techniques, and its photocatalytic behavior was investigated for degradation of ciprofloxacin under visible light irradiation. The Fe3O4/CuO@C material presented a porous structure with a rough surface of about 4–20 μm, and was composed of the Fe3O4/CuO nanocomposite uniformly distributed on a carbon support. The band gap energy of the obtained composite was found to be 2.0 eV, which was nearly two times lower than that of Fe3O4@C and CuO@C. As a result, Fe3O4/CuO@C exhibited high photocatalytic activity, achieving a degradation efficiency of 98.5% after 120 min irradiation at the optimum conditions (a catalyst dosage of 0.5 g L−1, pH of 7, CIP concentration of 15 mg L−1). The mechanism of ciprofloxacin degradation by Fe3O4/CuO@C was elucidated with the main contribution of O2−and OH reactive radicals. The new composite catalyst could easily be recovered from the treated solution using an external magnetic field due to its superparamagnetic nature. Fe3O4/CuO@C also showed good reusability and stability. The overall results indicated that the synthesized composite has significant application potential for controlling the risk of antibiotics in wastewater.

Preparation and Application of MOF-Based Hydrogel Materials

Preparation and Application of MOF-Based Hydrogel Materials

Recent progress in development of efficient electrocatalyst for methanol oxidation reaction in direct methanol fuel cell

The human craving for energy is continually mounting and becoming progressively difficult to Gratify. At present, the world's massive energy demands are chiefly encountered by nonrenewable and benign fossil fuels. However, the development of dynamic energy cradles for a gradually thriving world to lessen fossil fuel reserve depletion and environmental concerns are persistent issues for society at present. The discovery of copious nonconventional resources to fill the gap between energy petition and supply is the extreme obligation of the modern era. A new emergent, clean, and robust alternate of fossil fuels are the fuel cells. Among the different types of fuel cells, direct methanol fuel cells are an outstanding option for light-duty vehicles and portable devices. A critical tactic for striving and sustainable energy sources is the production of highly proficient, economical, and green catalysts for energy storage and conversion devices. Up till now a broad range of research work is available to use Pt and modify Pt-based electrocatalysts to augment the CH3OH oxidation process. Platinum-based nanocubes, nanorods, nanoflower, hybrids of Pt with metal-oxides such as Fe2O3, TiO2, SnO2, MnO, Cu2O, ZnO, and with conducting polymers are extensively utilized in both acidic and basic media. Moreover, Pd-based materials, transition metal-based materials as well as MOF and MOF-derived materials are also the point of interest for researchers nowadays. However, the problem associated with their practical applications is that they can be effectively employed in basic media due to comparative less stability in acidic medium. This review article will deliver a broad vision of the current progress of the MOR process concerning noble metals, transition metals, and MOF-based materials.

A new strategy for the preparation of core-shell MOF/Polymer composite material as the mixed-mode stationary phase for hydrophilic interaction/ reversed-phase chromatography

A facile method for efficient synthesis of core-shell composite material was proposed. In this method, the silica microspheres were co-modified with metal organic framework (MOF-235) and polyethylene glycol polymer (PEG) and used as mixed-mode stationary phase (MOF-235@PEG@silica) for high-performance liquid chromatography. Elemental analysis, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and Brunauer-Emmett-Teller etc. methods were used to investigate the properties of the core-shell composite material. The MOF-235@PEG@silica stationary phase showed flexible selectivity for the separation of both hydrophilic and hydrophobic compounds especially for the separation of nine alkaloids, which showed superior hydrophilic separation performance than previous MOF-based composite stationary phases. Some factors including the pH of buffer salt, the ratio of organic phase and water phase in the mobile phase have been investigated, suggesting that the chromatographic retention mechanism of the column was a mixed mode of hydrophilic and reversed phase. The composite material also showed excellent chromatographic repeatability with the RSDs of the retention time found to be 0.2%–0.6% (n = 10) and the standard addition test in the actual sample proved that it can be used for practical sample analysis. In short, it provided a general way for preparing MOFs-based composites as mixed-mode chromatographic stationary phases, and changed the current status of MOF-based composite materials as single mode chromatographic stationary phases.

Synthesis strategies and emerging mechanisms of metal-organic frameworks for sulfate radical-based advanced oxidation process: A review

• State-of-the-art MOFs-based materials in SR-AOPs for environmental remediation are overviewed. • The synthetic strategies of multifarious MOFs-based materials are summarized. • The effects of structure on the catalytic activities and the circumstance of radical and non-radical pathways are discussed. • DFT for the exploration of possible mechanisms in MOFs-based SR-AOPs are exhibited. • Prospects are highlighted for future research in the field of MOFs-based SR-AOPs. Recently, metal–organic frameworks (MOFs) based materials as the emerging catalysts for sulfate radical-based advanced oxidation processes (SR-AOPs) applications have progressively become a burgeoning research field. Herein, an in-depth overview of state-of-the-art MOFs-based materials currently available in SR-AOPs applications for environmental remediation is presented. The synthetic strategies of different types of MOFs-based materials are summarized. Most importantly, particular emphasis is placed on the applications of MOFs-based materials in SR-AOPs for wastewater treatment. Identification of reactive oxygen species (ROS) generated from the radical and non-radical pathways is addressed. Moreover, the theoretical calculations based on density functional theory (DFT) to predict and explore the possible reaction mechanisms in MOFs-based SR-AOPs are summarized and discussed. Special attention has been focused on the effects of structure on the catalytic activities and the circumstance of radical and non-radical reaction mechanisms in MOFs-based SR-AOPs. Finally, the unresolved challenges of the existent MOFs-based SR-AOPs are pointed out and the outlooks of future research directions are proposed.

Recent advances in lithium-based batteries using metal organic frameworks as electrode materials

Metal organic frameworks (MOFs) show excellent electrochemical performances due to their ultrahigh porosity, large specific surface area, and easy functionalization. These characteristics make it fascinating electrode materials with excellent electrochemical performance for the currently dominated lithium-based batteries (e.g., Li-ion batteries, Li-S batteries, Li-O2 batteries). Hence, this review summarizes the recent advances of MOFs-based materials as an electrode for high-performance lithium-ion storage. Firstly, we briefly describe the development history, principle, and mechanism of the lithium-based batteries. Then, the recent advances of MOFs/MOFs composite and MOF-derived materials employed as electrode materials for Lithium-ion batteries, Li-S batteries, and Li-O2 batteries are reviewed with their electrochemical performances. Finally, we conclude and point out the future direction of MOFs-related materials for lithium-based batteries.

(Invited) Programmed Assembly of Designer Solids from Molecular Building Blocks: A Route Towards Digitalization of Materials Research?

Realizing multifunctional “Designer Solids” by programmed assembly of building units taken form libraries is a very appealing objective in connection with Materials Research entering the Information Era. Metal-organic frameworks (MOFs) have attracted a huge interest in this context, owing to their enormous wealth of different compounds – the number of characterized elements of this rapidly growing class of materials has just exceeded 100.000. Here, we will focus on a subset of MOF-based functional materials, including electrochemical, photoelectrochemical, photovoltaic and optical devices. In addition to 3D structures, also 2D interfaces in MOF heterostructures are of interest, e.g. with regard to photon-upconversion. Since the fabrication of reliable and reproducible contacts to MOF-materials represent a major challenge, we have developed a layer-by-layer (lbl) deposition method to produce well-defined, highly oriented and monolithic MOF thin films on a number of different substrates. The resulting films are referred to as SURMOFs [1,2]. The fabrication of hetero-multilayers (see Fig. 1) is rather straightforward with this lbl method. In this talk, we will describe the principles of SURMOF fabrication as well as the results of systematic investigations of electrical and photophysical properties exhibited by empty MOFs and after loading their pores with functional guests. As a final point, we will discuss further applications realized by loading MOFs with nanoparticles or quantum dots. We will close with a more general discussion on the potential of programming functionalities into MOFs using in-silico screening methods.[3]

Ultrathin Mn Doped Ni‐MOF Nanosheet Array for Highly Capacitive and Stable Asymmetric Supercapacitor

In this study, we demonstrate that an Mn-doped ultrathin Ni-MOF nanosheet array on nickel foam (Mn0.1 -Ni-MOF/NF) serves as a highly capacitive and stable supercapacitor positive electrode. The Mn0.1 -Ni-MOF/NF shows an areal capacity of 6.48 C cm-2 (specific capacity C: 1178 C g-1 ) at 2 mA cm-2 in 6.0 m KOH, outperforming most reported MOF-based materials. More importantly, it possesses excellent cycle stability to maintain 80.6 % capacity after 5000 cycles. An asymmetric supercapacitor device utilizing Mn0.1 -Ni-MOF/NF as the positive electrode and activated carbon as the negative electrode attains a high energy density of 39.6 Wh kg-1 at 143.8 Wkg-1 power density with a capacitance retention of 83.6 % after 5000 cycles.

The Application of Metal-Organic Frameworks and Their Derivatives for Supercapacitors.

Supercapacitors (SCs), one of the most popular types of energy-storage devices, present lots of advantages, such as large power density and fast charge/discharge capability. Being the promising SCs electrode materials, metal–organic frameworks (MOFs) and their derivatives have gained ever-increasing attention due to their large specific surface area, controllable porous structure and rich diversity. Herein, the recent development of MOFs-based materials and their application in SCs as the electrode are reviewed and summarized. The preparation method, the morphology of the materials and the electrical performance of various MOFs and their derivatives (such as carbon, metal oxide/hydroxide and metal sulfide) are briefly discussed. Most of recent works concentrate on Ni-, Co- and Mn-MOFs and their composites/derivatives. Conclusions and our outlook for the researches are also given, which would be a valuable guideline for the rational design of MOFs materials for SCs in the near future.

Dual synergistic effect of S-doped carbon bridged semi crystalline MILN-based Co3S4/MnS2 nanostructure in electrocatalytic overall water splitting

Rapid electron transfer and abundant existence of active center are the keys for high performance catalysts. Here, an efficient bifunctional electrocatalyst, S-doped carbon bridged semi crystalline MILN-based Co3S4/MnS2 nanostructure prepared from MIL-88B(Co/Mn)-NH2 is constructed for overall water splitting. This catalyst not only acquires additional reaction sites through the dispersion of the metal centers, but also achieves fast delivery of electrons between Co3S4 and MnS2 through the S-doped carbon bridge. The strong electron donating ability of -NH2 and S2− and the excellent valence changing ability of two different transition metal centers make this material achieve a dual synergistic effect, greatly promoting the overall water splitting performance of the catalyst. In addition, high catalytic ability for HER is attribute to the amorphous component in the semicrystal MILN-based Co3S4/MnS2. The operation of water splitting by this catalyst with synergistic effect obtained a current density of 20 mA cm−2 at a low voltage of 1.561 V and a stable operation for 80 h. This work provides a new insight into the design of MOF-based electrocatalytic materials for electrochemical water splitting.

A porous Eu(III)-containing MOF: selective detection of Cr2O72– and treatment activity on the uterine fibroids by reducing TGF-β production and mmp expression

Metal–organic frameworks (MOFs) composed of metal ions and organic ligands via the coordination bonds have evolved as an emerging class of functional materials showing promising applications in the fluorescent detection and biomedicine, however, seldom reports combine the two properties in one type of MOF-based materials. Herein, a novel metal–organic framework (MOF) material containing Eu(III) of {[Eu(HL)(H2O)](DMF)3(H2O)4}n (1) based on 9-(2,6-dicarboxy-pyridin-4-yl)-9H-carbazole-3,6-dicarboxylic acid (H4L), a tetracarboxylic ligand, has been prepared under the solvothermal conditions. Furthermore, this Eu-MOF reflects strong red luminescence and outstanding water stability, which in-depth demonstrate it is a kind of luminescent sensor with highly sensitive and selective for the Cr2O72–, and it possesses low limit of detection and high coefficient of quenching. More importantly, complex 1 could be reused at least for fives without loss of the detection performance and framework integrity, which is quite rare among MOF-based sensors for Cr2O72–. In addition, the treatment effect of compound against the uterine fibroids was assessed in biological research. The detection of enzyme linked immunosorbent assay (ELISA) was firstly conducted to determine the transforming growth factor-β (TGF-β) content levels produced by the endometrial cells. Next, the mmp7 and mmp3 relative expression levels in the endometrial cells were detected via the real time reverse transcription-polymerase chain reaction (RT-PCR) method.

Hierarchical self-supporting sugar gourd-shape MOF-derived NiCo2O4 hollow nanocages@SiC nanowires for high-performance flexible hybrid supercapacitors

Rational construction of hierarchical electrode materials has been a research hotspot in the field of energy storage. In this work, metal–organic framework (MOF) derived hollow NiCo2O4 nanocages (NCs) were strung by interwoven SiC nanowires (NWs) network on carbon cloth (CC), forming a unique sugar gourd-like core–shell architecture, which were fabricated via a multi-step process containing of chemical vapor deposition, solution reaction of MOF templates, ion exchanging/etching and subsequent heat treatment. Benefiting from the unique structural advantages, such as hierarchical porous structure with abundant active sites for electrochemical reactions and interwoven conductive networks for electron transport, the formed core-shelled CC/SiCNWs@NiCo2O4NCs as a binder supercapacitor electrode exhibits excellent electrochemical performance with a large specific capacitance (1377.6F g−1 at a current density of 1 A g−1), good rate capability (68.8% capacitance retention at 20 A g−1) and excellent cycling stability (88.3% capacitance retention after 6000 cycles). Furthermore, the hybrid supercapacitor based on CC/SiCNWs@NiCo2O4NCs and activated carbon, not only delivers a high energy density of 46.58 Wh kg−1 at the power density of 800 W kg−1, but also possesses good flexibility with high capacitance retention, exhibiting the application potential in the field of flexible energy storage. More importantly, our work gives a new thinking for structural design of SiCNWs-based and MOF-based electrode materials for high-performance flexible energy storage.

Facile Preparation of In-Situ S-Doped Flake Carbon Materials from Metal-Organic Frameworks and Its Application in Electrochemical Detection of Hg (II)

S-doped carbon materials have recently attracted much attention as electrode materials for electrocatalysis and sensors applications. Herein, we report a facile route for the preparation in situ of flake S-doped carbon nanomaterial by using plate-like sulfur-containing metal-organic frameworks (MOFs) as a pyrolytic precursor without additional carbon and sulfur sources. The resultant MOFs-derived carbon (denoted as PSMC) was further characterized and analyzed by scanning electron microscope, transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy. Then a highly sensitive electrochemical sensor for selective determination of Hg (II) was achieved by designing PSMC as the active electrode material. The sensitivity of Hg (II) at the sensor is 2.12[Formula: see text][Formula: see text]A[Formula: see text]ppb[Formula: see text][Formula: see text]cm[Formula: see text] according to the slope of the calibration plot and electrode area. Finally, the PSMC-based sensor was proved feasible in river water sample analyses. This work may also provide a valuable clue for the preparation of flake S-doped carbon sensing material as a new application of MOFs-based materials.¡abs¿

Tunable colors and white-light emissions by encapsulation of guest molecules or ions into a flexible metal–organic framework

Abstract Metal-organic frameworks (MOFs) are well known for their tunable structure and porosity with various important applications. In particular, their performance can be further improved by encapsulating luminescent guest molecules or lanthanide ions. This work aims to develop tunable colors and white-light emission materials by encapsulation of organic molecules and Eu3+ (or Tb3+) ions within a porous MOF (USTC-1). Various guest organic molecules or lanthanide ions are encapsulated into this MOF, yielding blue, blue-green, green, pink and red phosphorescence, respectively. Significantly, white-light emission can be achieved by encapsulating yellow- or green/red-emitting guest organic molecule into blue-emissive USTC-1 and adjusting the content of guest organic molecules. In addition, the white-light emissive USTC-1 composite materials can also be easily achieved by variation of the inclusion amount of single Eu3+ or Tb3+ ion in the host framework of USTC-1. The present work firstly reported white-light MOF-based composite materials by encapsulation of single organic molecule (non-dye molecule), and such strategy may open new perspectives for developing novel white-light emission materials by encapsulation of organic molecules or lanthanide ions.

Necklace-like C-ZIF-8@MWCNTs fabricated by electrochemical deposition towards enhanced supercapacitor

Electrochemical deposition is a facile technique to fabricate metal organic frameworks (MOFs) based materials in a short reaction time under mild conditions. In this work, novel necklace-like zeolitic imidazole framework@multiwalled carbon nanotubes (ZIF-8@MWCNTs) composite was synthesized by electrochemical method for the first time and then used as precursor for subsequent carbonization and acid treatment. The resultant porous carbon material (C-ZIF-8@MWCNTs) maintained the necklace-like structure with a high surface area of 1063.2 m2 g−1. When used as electrode material for supercapacitor, the C-ZIF-8@MWCNTs demonstrated a high specific capacitance of 259.2 F g−1 at the current density of 0.5 A g−1. Further, the capacitance retention could reach 92% after 5000 cycles under the current density of 15 A g−1. Due to the large specific surface area of the porous carbon derived from ZIF-8 and the intrinsic high conductivity, the C-ZIF-8@MWCNTs displayed good rate ability and cycle performance. The current work can expand the method to synthesize functional MOFs-based materials for advanced applications.