A review on the field patents and recent developments over the application of metal organic frameworks (MOFs) in supercapacitors

MOF/graphene oxide based composites in smart supercapacitors: a comprehensive review on the electrochemical evaluation and material development for advanced energy storage devices

The surge in interest surrounding energy storage solutions, driven by the demand for electric vehicles and the global energy crisis, has spotlighted the effectiveness of carbon-based supercapacitors in meeting high-power requirements. Concurrently, metal-organic frameworks (MOFs) have gained attention as a template for their integration with graphene oxide (GO) in composite materials which have emerged as a promising avenue for developing high-power supercapacitors, elevating smart supercapacitor efficiency, cyclic stability, and durability, providing crucial insights for overcoming contemporary energy storage obstacles. The identified combination leverages the strengths of both materials, showcasing significant potential for advancing energy storage technologies in a sustainable and efficient manner. In this research, an in-depth review has been presented, in which properties, rationale and integration of MOF/GO composites have been critically examined. Various fabrication techniques have been thoroughly analyzed, emphasizing the specific attributes of MOFs, such as high surface area and modifiable porosity, in tandem with the conductive and stabilizing features of graphene oxide. Electrochemical characterizations and physicochemical mechanisms underlying MOF/GO composites have been examined, emphasizing their synergistic interaction, leading to superior electrical conductivity, mechanical robustness, and energy storage capacity. The article concludes by identifying future research directions, emphasizing sustainable production, material optimization, and integration strategies to address the persistent challenges in the field of energy storage. In essence, this research article aims to offer a concise and insightful resource for researchers engaged in overcoming the pressing energy storage issues of our time through the exploration of MOF/GO composites in smart supercapacitors.

A Highly Robust and Conducting Ultramicroporous 3D Fe(II)-Based Metal-Organic Framework for Efficient Energy Storage

Exploitation of metal-organic framework (MOF) materials as active electrodes for energy storage or conversion is reasonably challenging owing to their poor robustness against various acidic/basic conditions and conventionally low electric conductivity. Keeping this in perspective, herein, a 3D ultramicroporous triazolate Fe-MOF (abbreviated as Fe-MET) is judiciously employed using cheap and commercially available starting materials. Fe-MET possesses ultra-stability against various chemical environments (pH-1 to pH-14 with varied organic solvents) and is highly electrically conductive (σ = 0.19 S m-1) in one fell swoop. By taking advantage of the properties mentioned above, Fe-MET electrodes give prominence to electrochemical capacitor (EC) performance by delivering an astounding gravimetric (304 F g-1) and areal (181 mF cm-2) capacitance at 0.5 A g-1 current density with exceptionally high cycling stability. Implementation of Fe-MET as an exclusive (by not using any conductive additives) EC electrode in solid-state energy storage devices outperforms most of the reported MOF-based EC materials and even surpasses certain porous carbon and graphene materials, showcasing superior capabilities and great promise compared to various other alternatives as energy storage materials.

Cobalt sulfide flower-like derived from metal organic frameworks on nickel foam as an electrode for fabrication of asymmetric supercapacitors

Metal-organic frameworks, as a kind of advanced nanoporous materials with metal centers and organic linkers, have been applied as promising electrode materials in energy storage devices. In this study, we are successfully prepared cobalt sulfide nanosheets (CoS) derived from the metal-organic framework on nickel foam (NF). The prepared electrodes are characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, Brunauer-Emmett-Teller and Barrett-Joyner-Halenda and electrochemical methods like voltammetry, galvanostatic charge-discharge curve and electrochemical impedance spectroscopy. The CoS/NF electrode demonstrates a high specific capacity of 377.5 mA h g-1 (1359 C g-1) at the current density of 2 A g-1, considerable rate performance and excellent durability (89.4% after 4000 cycles). A hybrid supercapacitor is assembled using CoS/NF as the positive electrode and activated carbon as the negative electrode, it shows a high energy density of 57.4 W h kg-1 at a power density of 405.2 W kg-1. The electrochemical results suggest that the CoS nanosheet arrays would possess excellent potential for applications in energy storage devices.

Telluride-Based Materials: A Promising Route for High Performance Supercapacitors

As supercapacitor (SC) technology continues to evolve, there is a growing need for electrode materials with high energy/power densities and cycling stability. However, research and development of electrode materials with such characteristics is essential for commercialization the SC. To meet this demand, the development of superior electrode materials has become an increasingly critical step. The electrochemical performance of SCs is greatly influenced by various factors such as the reaction mechanism, crystal structure, and kinetics of electron/ion transfer in the electrodes, which have been challenging to address using previously investigated electrode materials like carbon and metal oxides/sulfides. Recently, tellurium and telluride-based materials have garnered increasing interest in energy storage technology owing to their high electronic conductivity, favorable crystal structure, and excellent volumetric capacity. This review provides a comprehensive understanding of the fundamental properties and energy storage performance of tellurium- and Te-based materials by introducing their physicochemical properties. First, we elaborate on the significance of tellurides. Next, the charge storage mechanism of functional telluride materials and important synthesis strategies are summarized. Then, research advancements in metal and carbon-based telluride materials, as well as the effectiveness of tellurides for SCs, were analyzed by emphasizing their essential properties and extensive advantages. Finally, the remaining challenges and prospects for improving the telluride-based supercapacitive performance are outlined.

Transition Metal Catalysts for Atmospheric Heavy Metal Removal: A Review of Current Innovations and Advances

Atmospheric heavy metal pollution presents a severe threat to public health and environmental stability. Transition metal catalysts have emerged as a potent solution for the selective capture and removal of these pollutants. This review provides a comprehensive summary of current advancements in the field, emphasizing the efficiency and specificity of nanostructured transition metals, including manganese, iron, cobalt, nickel, copper, and zinc. Looking forward, we delve into the prospective trajectory of catalyst development, underscoring the need for materials with enhanced stability, regenerability, and environmental compatibility. We project that advancements in computational materials science, nanotechnology, and green chemistry will be pivotal in discovering innovative catalysts that are economically and environmentally sustainable. The integration of smart technologies for real-time monitoring and adaptive control is anticipated to revolutionize heavy metal remediation, ensuring efficient and responsive pollution abatement strategies in the face of evolving industrial scenarios and regulatory landscapes.

Metal-Organic Frameworks and Their Derivatives-Based Nanostructure with Different Dimensionalities for Supercapacitors

With the urgent demand for the achievement of carbon neutrality, novel nanomaterials, and environmentally friendly nanotechnologies are constantly being explored and continue to drive the sustainable development of energy storage and conversion installations. Among various candidate materials, metal-organic frameworks (MOFs) and their derivatives with unique nanostructures have attracted increasing attention and intensive investigation for the construction of next generation electrode materials, benefitting from their unique intrinsic characteristics such as large specific surface area, high porosity, and chemical tunability as well as the interconnected channels. Nevertheless, the poor electrochemical conductivity severely limits their application prospects, hence a variety of nanocomposites with multifarious structures have been designed and proposed from different dimensionalities. In this review, recent advances based on MOFs and their derivatives in different dimensionalities ranging from 1D nanopowders to 2D nanofilms and 3D aerogels, as well as 4D self-supporting electrodes for supercapacitors are summarized and highlighted. Furthermore, the key challenges and perspectives of MOFs and their derivatives-based materials for the practical and sustainable electrochemical energy conversion and storage applications are also briefly discussed, which may be served as a guideline for the design of next-generation electrode materials from different dimensionalities.

One-pot synthesis of bimetallic Fe-Cu metal-organic frameworks composite for the elimination of organic pollutants via peroxymonosulphate activation

A series of bimetallic of FeCu metal-organic frameworks (MOFs) have been synthesised using a solvothermal process by varying the ratio between the two metals. Further, the bimetallic MOF catalysts were characterised by X-ray powder diffraction, scanning electron microscopy, and infrared spectroscopy techniques. Their catalytic properties for activation of peroxymonosulphate (PMS) have been tested by the removal of a model dye, rhodamine B. As a result, NH2-Fe2.4Cu1-MOF demonstrated the highest degradation, the effect of the ratio NH2-Fe2.4Cu1-MOF/PMS has been studied, and the main reactive species have been assessed. The application of these MOFs in powder form is difficult to handle in successive batch or flow systems. Thus, this study assessed the feasibility of growing NH2-Fe2,4Cu1-MOF on polyacrylonitrile (PAN) spheres using the one-pot solvothermal synthesis method. The optimisation of the catalytic activity of the synthesised composite (NH2-Fe2.4Cu1-MOF@PAN) has been evaluated by response surface methodology using a central composite face-centred experimental design matrix and selecting as independent variables: time, PMS concentration, and catalyst dosage. Based on the results, the optimisation of the operational conditions has been validated. At 2.5 mM PMS, 90 min, and 1.19 g·L-1 of catalyst dosage, maximum degradation (80.92%) has been achieved, which doubles the removal values obtained in previous studies with other MOFs. In addition, under these conditions, the catalyst has been proven to maintain its activity and stability for several cycles without activity loss.

Advances of Electroactive Metal-Organic Frameworks

The preparation of electroactive metal-organic frameworks (MOFs) for applications of supercapacitors and batteries has received much attention and remarkable progress during the past few years. MOF-based materials including pristine MOFs, hybrid MOFs or MOF composites, and MOF derivatives are well designed by a combination of organic linkers (e.g., carboxylic acids, conjugated aromatic phenols/thiols, conjugated aromatic amines, and N-heterocyclic donors) and metal salts to construct predictable structures with appropriate properties. This review will focus on construction strategies of pristine MOFs and hybrid MOFs as anodes, cathodes, separators, and electrolytes in supercapacitors and batteries. Descriptions and discussions follow categories of electrochemical double-layer capacitors (EDLCs), pseudocapacitors (PSCs), and hybrid supercapacitors (HSCs) for supercapacitors. In contrast, Li-ion batteries (LIBs), Lithium-sulfur batteries (LSBs), Lithium-oxygen batteries (LOBs), Sodium-ion batteries (SIBs), Sodium-sulfur batteries (SSBs), Zinc-ion batteries (ZIBs), Zinc-air batteries (ZABs), Aluminum-sulfur batteries (ASBs), and others (e.g., LiSe, NiZn, H⁺ , alkaline, organic, and redox flow batteries) are categorized for batteries.

A heterostructure of a 2D bimetallic metal-organic framework assembled on an MXene for high-performance supercapacitors

Two-dimensional (2D) MXenes (transition metal carbide or carbonitride) and metal-organic frameworks (MOFs) have emerged as appealing electrode materials for supercapacitors due to the advantages of each material and a 2D structure. However, a solitary MXene or MOF suffers from either inadequate redox reactive sites or low electronic conductivity and instability. Here, NiCo-MOF/MXene heterostructures are fabricated by assembling ultrathin 2D bimetallic NiCo-MOF nanosheets on exfoliated MXene nanosheets by a simple room-temperature ultrasonic method. The 2D/2D NiCo-MOF/MXene heterostructures combine the advantages of a MOF, MXene and hierarchical structure, i.e. a large surface area, a highly electrically conductive network, rapid ion diffusion and structural stability. As a result, the optimal NiCo-MOF/M₁₀ electrode exhibits a highly improved capacitance (1176.8 F g^-1vs. 653.4 F g^-1) and cycle life (72.5% vs. 50.5%), compared with the pristine NiCo-MOF. Moreover, a two-electrode cell using NiCo-MOF/M₁₀ as the cathode shows outstanding energy storage capability. This study provides an opportunity to enhance energy storage by designing 2D heterostructures.

Review on Metal-Organic Framework Classification, Synthetic Approaches, and Influencing Factors: Applications in Energy, Drug Delivery, and Wastewater Treatment

Metal ions or clusters that have been bonded with organic linkers to create one- or more-dimensional structures are referred to as metal-organic frameworks (MOFs). Reticular synthesis also forms MOFs with properly designated components that can result in crystals with high porosities and great chemical and thermal stability. Due to the wider surface area, huge pore size, crystalline nature, and tunability, numerous MOFs have been shown to be potential candidates in various fields like gas storage and delivery, energy storage, catalysis, and chemical/biosensing. This study provides a quick overview of the current MOF synthesis techniques in order to familiarize newcomers in the chemical sciences field with the fast-growing MOF research. Beginning with the classification and nomenclature of MOFs, synthesis approaches of MOFs have been demonstrated. We also emphasize the potential applications of MOFs in numerous fields such as gas storage, drug delivery, rechargeable batteries, supercapacitors, and separation membranes. Lastly, the future scope is discussed along with prospective opportunities for the synthesis and application of nano-MOFs, which will help promote their uses in multidisciplinary research.

Novel In Situ Growth of ZIF-8 in Porous Epoxy Matrix for Mechanically Robust Composite Electrolyte of High-Performance, Long-Life Lithium Metal Batteries

Polymer electrolytes (PEs) with high flexibility, low cost, and excellent interface compatibility have been considered as an ideal substitute for traditional liquid electrolytes for high safety lithium metal batteries (LMBs). Nevertheless, the mechanical strength of PEs is generally poor to prevent the growth of lithium dendrites during the charge/discharge process, which seriously restricts their wide practical applications. Herein, a mechanical robust ZIF-8/epoxy composite electrolyte with unique pore structure was prepared, which effectively inhibited the growth of lithium dendrites. Meanwhile, the in situ growth of ZIF-8 in porous epoxy matrix can promote the uniform flux and fast transport of lithium ions. Ultimately, the optimal electrolyte shows high ionic conductivity (2.2 × 10−3 S cm−1), wide electrochemical window (5 V), and a large Li+ transference number (0.70) at room temperature. The Li||NCM811 cell using the optimal electrolyte exhibits high capacity and excellent cycling performance (83.2% capacity retention with 172.1 mA h g−1 capacity retained after 200 cycles at 0.2 C). These results indicate that the ZIF-8/epoxy composite electrolyte is of great promise for the application in LMBs.

Metal-Organic Framework Materials for Electrochemical Supercapacitors

Exploring new materials with high stability and capacity is full of challenges in sustainable energy conversion and storage systems. Metal-organic frameworks (MOFs), as a new type of porous material, show the advantages of large specific surface area, high porosity, low density, and adjustable pore size, exhibiting a broad application prospect in the field of electrocatalytic reactions, batteries, particularly in the field of supercapacitors. This comprehensive review outlines the recent progress in synthetic methods and electrochemical performances of MOF materials, as well as their applications in supercapacitors. Additionally, the superiorities of MOFs-related materials are highlighted, while major challenges or opportunities for future research on them for electrochemical supercapacitors have been discussed and displayed, along with extensive experimental experiences.

A high-performance electrochemical sensor for sensitive detection of tetracycline based on a Zr-UiO-66/MWCNTs/AuNPs composite electrode

Herein, a high-performance electrochemical sensor was constructed based on a metal-organic framework (Zr-UiO-66)/multi-carbon nanotubes/gold nanoparticles (Zr-UiO-66/MWCNTs/AuNPs) composite modified glassy carbon electrode for sensitive determination of tetracycline. The morphology, structure, and performance of Zr-UiO-66/MWCNTs/AuNPs were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), and electrochemical techniques. The Zr-UiO-66/MWCNTs/AuNPs nanohybrids exhibited excellent electrocatalytic activity towards the oxidation of tetracycline, mainly because of the synergistic effect of the MOFs, MWCNTs, and gold nanoparticles. The electrochemical kinetics and catalytical mechanism of tetracycline were demonstrated, proving that tetracycline's electrocatalytic oxidation reaction was an absorption-controlled two-step process involving the transfer of two protons and two electrons, respectively. Furthermore, a simple and facile method was used to achieve the regeneration of the absorbed saturated electrode. A low concentration of tetracycline was detected by amperometry with the linear ranges of 5 × 10^-7 to 2.25 × 10^-4 mol L^-1 (R² = 0.9941), the sensitivity was 45.4 mA L mol^-1, and the limit of detection was as low as 1.67 × 10^-7 mol L^-1 (S/N = 3). In addition, the composite electrode demonstrated high selectivity (interference deviation of ± 5%), satisfactory reproductivity (RSD of 5.31%), and long-term stability (easy regeneration) and was successfully applied in the analysis of tetracycline antibiotics in actual samples. Thus, the proposed electrode provides a promising and prospective MOFs-based sensing platform for the detection of tetracyclines in the environment.

Approaches to Enhancing Electrical Conductivity of Pristine Metal-Organic Frameworks for Supercapacitor Applications

Metal-organic frameworks (MOFs), known as porous coordination polymers, have attracted intense interest as electrode materials for supercapacitors (SCs) owing to their advantageous features including high surface area, tunable porous structure, structural diversity, etc. However, the insulating nature of most MOFs has impeded their further electrochemical applications. A common solution for this issue is to transform pristine MOFs into more stable and conductive metal compounds/porous carbon materials through pyrolysis, which however losses the inherent merits of MOFs. To find a consummate solution, recently a surge of research devoted to improving the electrical conductivity of pristine MOFs for SCs has been carried out. In this review, the most related research work on pristine MOF-based materials is reviewed and three effective strategies (chemical structure design of conductive MOFs (c-MOFs), composite design, and binder-free structure design) which can significantly increase their conductivity and consequently the electrochemical performance in SCs are proposed. The conductivity enhancement mechanism in each approach is well analyzed. The representative research works on using pristine MOFs for SCs are also critically discussed. It is hoped that the new insights can provide guidance for developing high-performance electrode materials based on pristine MOFs with high conductivity for SCs in the future.

Metal-organic framework (MOF) composites as promising materials for energy storage applications

Metal-organic framework (MOF) composites are considered to be one of the most vital energy storage materials due to their advantages of high porousness, multifunction, various structures and controllable chemical compositions, which provide a great possibility to find suitable electrode materials for batteries and supercapacitors. However, MOF composites are still in the face of various challenges and difficulties that hinder their practical application. In this review, we introduce and summarize the applications of MOF composites in batteries, covering metal-ion batteries, lithium-sulfur batteries, lithium-oxygen batteries and zinc-air batteries, as well as supercapacitors. In addition, the application challenges of MOF composites in batteries and supercapacitors are also summarized. Finally, the basic ideas and directions for further development of these two types of electrochemical energy storage devices are proposed.

Five-FU@CuS/NH2 -UiO-66 as a drug delivery system for 5-fluorouracil to colorectal cancer cells

In this study, copper sulfide nanoparticles (CuS-NPs), which can improve the antiproliferative properties of conventional anticancer drugs such as 5-fluorouracil (5-FU), were incorporated into the pores of amine-functionalized UiO-66 (CuS/NH₂ -UiO-66). The introduced nano-drug delivery system was exerted to perform an in vitro treatment on CT-26 mouse colorectal cancer cells. The synthesized final product was labeled as 5-FU@CuS/NH₂ -UiO-66 and characterized through conventional methods including X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) analysis, Ultraviolet-Visible (UV-Vis) analysis, Inductively coupled plasma mass spectrometry (ICP-MS), and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. In contrast to 5-FU, the outcomes of the cytotoxicity assay lacked any comparable results for 5-FU@CuS/NH₂ -UiO-66.

Potential Applications of Nickel-Based Metal-Organic Frameworks and their Derivatives

Metal-Organic Frameworks (MOFs), a novel class of porous extended crystalline structures, are favored in different fields of heterogeneous catalysis, CO₂ separation and conversion, and energy storage (supercapacitors) due to their convenience of synthesis, structural tailor-ability, tunable pore size, high porosity, large specific surface area, devisable structures, and adjustable compositions. Nickel (Ni) is a ubiquitous element extensively applied in various fields of catalysis and energy storage due to its low cost, high abundance, thermal and chemical stability, and environmentally benign nature. Ni-based MOFs and their derivatives provide us with the opportunity to modify different properties of the Ni center to improve their potential as heterogeneous catalysts or energy storage materials. The recent achievements of Ni-MOFs and their derivatives as catalysts, membrane materials for CO₂ separation and conversion, electrode materials and their respective performance have been discussed in this review.

A new and systematic review on the efficiency and mechanism of different techniques for OPFRs removal from aqueous environments

Organic phosphorus flame retardants (OPFRs), as a new type of emerging contaminant, have drawn great attention over the last few years, due to their wide distribution in aquatic environments and potential toxicities to humans and living beings. Various treatment methods have been reported to remove OPFRs from water or wastewater. In this review, the performances and mechanisms for OPFRs removal with different methods including adsorption, oxidation, reduction and biological techniques are overviewed and discussed. Each technique possesses its advantage and limitation, which is compared in the paper. The degradation pathways of typical OPFRs pollutants, such as Cl-OPFRs, alkyl OPFRs and aryl OPFRs, are also reviewed and compared. The degradation of those OPFRs depends heavily upon their structures and properties. Furthermore, the implications and future perspectives in such area are discussed. The review may help identify the research priorities for OPFRs remediation and understand the fate of OPFRs during the treatment processes.

Progress in Metal-Organic Framework Catalysts for Selective Catalytic Reduction of NOx: A Mini-Review

Nitrogen oxides released from the combustion of fossil fuels are one of the main air pollutants. Selective catalytic reduction technology is the most widely used nitrogen oxide removal technology in the industry. With the development of nanomaterials science, more and more novel nanomaterials are being used as catalysts for the selective reduction of nitrogen oxides. In recent years, metal-organic frameworks (MOFs), with large specific surface areas and abundant acid and metal sites, have been extensively studied in the selective catalytic reduction of nitrogen oxides. This review summarizes recent progress in monometallic MOFs, bimetallic MOFs, and MOF-derived catalysts for the selective catalytic reduction of nitrogen oxides and compares the reaction mechanisms of different catalysts. This article also suggests the advantages and disadvantages of MOF-based catalysts compared with traditional catalysts and points out promising research directions in this field.

Sorption based easy-to-use low-cost filters derived from invasive weed biomass for dye contaminated water cleanup

Today, the development of functional nanostructured materials with specified morphologies utilizing environmentally friendly techniques is a very appealing topic in materials chemistry. Much emphasis has recently been paid to the utilization of biomass to make functional carbonaceous materials of varying forms, specifically carbon helices, with greater implications for the environment, economy, and society. A metal-catalyzed chemical vapour deposition technique has been developed for the fabrication of such carbon helices from nonrenewable hydrocarbons. Also, functionalization approaches were seen to necessitate high temperatures, hazardous gases, and multi-step processes. Herein, we have synthesized tendril-like functional carbon helices (HTCs) from toxic bio-weed, Parthenium hysterophorus as the carbon source by a greener solvothermal method employing deep eutectic solvent (DES) as both soft template and catalyst. Further, for the first time by taking advantage of the in-built chemical functionalities, HTCs were physically activated in an inert atmosphere at 900 °C (AHC) and functionalized with manganese oxide at room temperature by employing DES. Furthermore, the materials were characterized using FE-SEM, EDX, FT-IR, XRD, and BET analysis, where a surface area of 313.12 m² g⁻¹ was achieved with a robust removal of 99.68% of methylene blue (MB) dye with a flux rate of 7432.71 LMH in a simulated continuous flow system. The obtained material was also evaluated for its specificity towards contaminant removal from an aqueous medium. Thus, Mn₃O₄/AHC membranes exhibited great promise as an easy-to-use filter for organic contaminant cleanup, with about 91% rejection of MB even at the end of the 10^th cycle, indicating its potential.

Today, the development of functional nanostructured materials with specified morphologies utilizing environmentally friendly techniques is a very appealing topic in materials chemistry.

Process of metal-organic framework (MOF)/covalent-organic framework (COF) hybrids-based derivatives and their applications on energy transfer and storage

The fossil-fuel shortage and severe environmental issues have posed ever-increasing demands on clean and renewable energy sources, for which the exploration of electrocatalysts has been a big challenge toward energy transfer and storage. Some indispensable features of electrocatalysts, such as large surface area, controlled structure, high porosity, and effective functionalization, have been proved to be critical for the improvement of electrocatalytic activities. Recently, the rapid expansion of metal-organic frameworks (MOFs), covalent-organic frameworks (COFs), and porous-organic polymers has provided extensive opportunities for the development of various electrocatalysts. Moreover, combining diverse descriptions of porous-organic frameworks (such as MOFs and COFs) can generate amazing and fantastic properties, affording the formed MOF/COF (including core-shell MOF@MOF and MOF@COF and layer-on-layer MOF-on-MOF or COF-on-MOF) heterostructures wide applications in diverse fields, especially in clean energy and energy transfer. To further boosts electronic conductivity, catalytic performances, and energy storage abilities, these MOF/COF hybrid materials have been widely utilized as versatile precursors for the manufacture of transition metal catalysts embedded within mesoporous carbon nitrides (M@CN_x) and porous carbon nitride frameworks (CN_x) via a facile pyrolysis process. Given that these M@CN_x and CN_x hybrids are composed of abundant catalytic centers, rich functionalities, and large specific surface areas, vast applications in energy transfer and energy storage fields can be realized. In this mini-review, we summarize the preparation strategies of MOF/COF-based hybrids, as well as their derivatives, nanostructure formation mechanism of M@CN_x and CN_x hybrids from MOF/COF-based hybrid materials, and their applications as catalysts for driving diverse reactions and electrode materials for energy storage. Further, current challenges and future prospects of applying these derivatives into energy conversion and storage devices are also discussed.

A facile morphology tunable strategy of Zn-MOF derived hierarchically carbon materials with enhanced supercapacitive performance through the solvent effect

Metal–organic framework (MOF) derived porous carbon materials have been widely applied as active materials for supercapacitors due to their large specific surface area and ordered pore structure.

Synergetic Advantages of Atomically Coupled 2D Inorganic and Graphene Nanosheets as Versatile Building Blocks for Diverse Functional Nanohybrids

2D nanostructured materials, including inorganic and graphene nanosheets, have evoked plenty of scientific research activity due to their intriguing properties and excellent functionalities. The complementary advantages and common 2D crystal shapes of inorganic and graphene nanosheets render their homogenous mixtures powerful building blocks for novel high-performance functional hybrid materials. The nanometer-level thickness of 2D inorganic/graphene nanosheets allows the achievement of unusually strong electronic couplings between sheets, leading to a remarkable improvement in preexisting functionalities and the creation of unexpected properties. The synergetic merits of atomically coupled 2D inorganic-graphene nanosheets are presented here in the exploration of novel heterogeneous functional materials, with an emphasis on their critical roles as hybridization building blocks, interstratified sheets, additives, substrates, and deposited monolayers. The great flexibility and controllability of the elemental compositions, defect structures, and surface natures of inorganic-graphene nanosheets provide valuable opportunities for exploring high-performance nanohybrids applicable as electrodes for supercapacitors and rechargeable batteries, electrocatalysts, photocatalysts, and water purification agents, to give some examples. An outlook on future research perspectives for the exploitation of emerging 2D nanosheet-based hybrid materials is also presented along with novel synthetic strategies to maximize the synergetic advantage of atomically mixed 2D inorganic-graphene nanosheets.

Ultrahigh Rate Capability and Lifespan MnCo2 O4 /Ni-MOF Electrode for High Performance Battery-Type Supercapacitor

MnCo₂ O₄ is derived from a Co/Mn bimetallic metal-organic framework (MOF). Then Ni-MOF is directly grown on the surface of the obtained MnCo₂ O₄ to form a nano-flower structure with small balls. A large surface area, abundant active sites of MnCo₂ O₄ and porosity of Ni-MOF allow the prepared MnCo₂ O₄ /Ni-MOF composite material to deliver an excellent electrochemical performance. At the same time, an appropriate thermal treatment temperature of the MnCo₂ O₄ precursor is also very important for controlling the morphology of the obtained MnCo₂ O₄ and electrochemical performances of the resulted composite material including electric conductivity, specific capacitance and rate performance. The prepared MnCo₂ O₄ -600/Ni-MOF shows an ultrahigh rate performance (when the current density increases from 1 to 10 A g^-1 , the capacitance retention rate is as high as 93.41 %) and good cycle stability (the assembled asymmetric supercapacitor advice delivers a capacitance retention rate of 94.74 % after 20 000 charge and discharge cycles) as well as a relatively high specific capacitance. These excellent electrochemical properties indicate that MnCo₂ O₄ /Ni-MOF has a good application prospect in the market.

Hybrid Porous Crystalline Materials from Metal Organic Frameworks and Covalent Organic Frameworks

Two frontier crystalline porous framework materials, namely, metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), have been widely explored owing to their outstanding physicochemical properties. While each type of framework has its own intrinsic advantages and shortcomings for specific applications, combining the complementary properties of the two materials allows the engineering of new classes of hybrid porous crystalline materials with properties superior to the individual components. Since the first report of MOF/COF hybrid in 2016, it has rapidly evolved as a novel platform for diverse applications. The state-of-art advances in the various synthetic approaches of MOF/COF hybrids are hereby summarized, together with their applications in different areas. Perspectives on the main challenges and future opportunities are also offered in order to inspire a multidisciplinary effort toward the further development of chemically diverse, multi-functional hybrid porous crystalline materials.

Recent advances in metal-organic framework-based electrode materials for supercapacitors

Exploring porous electrode materials with designed micro/nano-structures is an effective way to realize high-performance supercapacitors (SCs). A metal-organic framework (MOF) is a porous crystalline material with a periodic structure formed by coordination of metal ions/clusters and organic ligands. Due to the excellent properties (e.g., large specific surface area, high porosity and tailorable structure), MOFs have been widely used in diverse applications. This Frontier article highlights the recent progress in the synthesis of MOF-based micro/nano-structured electrode materials including pristine MOFs, MOF composites and MOF derivatives, and their application in SCs. Furthermore, the challenges of MOF-based electrode materials and possible solutions are also discussed.

A ZIF-8 Host for Dendrite-Free Zinc Anodes and N,O Dual-doped Carbon Cathodes for High-Performance Zinc-Ion Hybrid Capacitors

Zn is a promising anode for aqueous energy storage owing to it intrinsic superior properties such as large capacity, abundant reserves, low potential and safety. But, the growth of dendrites during charge and discharge leads to a decrease in reversibility. In addition, further development of zinc-ion hybrid capacitors (ZICs) is seriously challenging because of the lack of an exceptional cathode. Herein, we use ZIF-8 annealed at 500 °C (annealed ZIF-8) as a host material for stable and dendrite-free Zn anodes. Utilization of annealed ZIF-8 results in dendrite-free Zn deposition and stripping as a result of its porous construction, which contains trace Zn. Furthermore, we firstly proposed innovative N,O dual-doped carbon which was designed by the derived ZIF-8 (ZIF-8 derived C) as cathode for high-energy and power-density ZICs. The new ZIC assembled by Zn@annealed ZIF-8 anode and ZIF-8 derived C cathode provides a capacity of 135.5 mAh g^-1 and an energy density of 108.4 Wh kg^-1 with a power density of 800 W kg^-1 at 1.0 A g^-1 . In addition, it shows outstanding cycling stability of 91% capacity retention after 6000 cycles at 5.0 A g^-1 . Moreover, the solid-state ZICs can drive LEDs and smart watches. This ZIC holds promise for the practical application of supercapacitors.

General fabrication of metal-organic frameworks on electrospun modified carbon nanofibers for high-performance asymmetric supercapacitors

Metal-organic framework (MOF)-based electrode materials have become a hot subject for supercapaitors. Herein, Ni-MOFs grown on Co nanoparticles modified carbon nanofibers (CNFs) (C-Co@MOF) are prepared via a facile process. Interestingly, the presence of Co nanoparticles in CNFs not only boosts the hybridization of CNF and MOFs, but also releases Co ions to participate in the growth of MOF, leading to a favorable electrochemical behavior. In detail, the specific capacitance of C-Co@MOF reaches 1201.6 F g^-1 that exceeds those of C-M@MOFs (M = Ni, V, Mo, Mn, Fe, Cu and Zn) and CNF@MOF. More importantly, an asymmetric solid-state supercapacitor is assembled using C-Co@MOF and nitrogen-doped carbon nanotubes derived from polyaniline as positive and negative electrode materials, respectively, representing a high energy density of 37.0 Wh kg^-1 and outstanding durability. This work highlights the superiority of electrospun CNFs modified by metal nanoparticles for the growth of MOF, showing great potential for electrochemical energy storage and conversion applications.

Polyvinylpyrrolidone (PVP) assisted in-situ construction of vertical metal-organic frameworks nanoplate arrays with enhanced electrochemical performance for hybrid supercapacitors

Construction of two-dimensional (2D) metal-organic frameworks (MOFs) for energy storage and conversion has attracted great attention due to the synergistic advantages of 2D nanostructures and MOFs. Herein, a Co-MOF material with different 2D morphologies of vertical nanoplate arrays and faveolate nanosheets are in-situ fabricated on Ni foam with and without using polyvinylpyrrolidone (PVP) as a regulator. Toward the application in energy storage, both of two morphologies of the Co-MOF exhibit good electrochemical properties. In particular, the vertical Co-MOF nanoplate arrays deliver a high areal capacity of 8.56 C/cm² at the current density of 5 mA/cm², which is much higher than that of faveolate Co-MOF nanosheets (2.39 C/cm² at 5 mA/cm²). Moreover, a hybrid supercapacitor (HSC) device using the Co-MOF nanoplate arrays positive electrode and activated carbon (AC) negative electrode is assembled, which delivers a volumetric capacitance of 17.9 F/cm³ at 10 mA/cm², a high energy density of 7.2 mW h cm^-3 and a good cyclic stability (retaining over 88.0% of initial capacitance after 3000 cycles). These findings demonstrate that the as-fabricated 2D Co-MOFs possess a huge potential in energy storage.

A luminescent metal–organic framework with tetragonal nanochannels as an efficient chemosensor for nitroaromatic explosives detection

A 3D MOF with nanosized channels can act as an effective fluorescence probe, showing obvious fluorescence “turn-off” for nitroaromatic explosives.