NiFe-Coordination Polymers-Derived Layered Double Hydroxides as Bifunctional Materials: Effect of the Ni : Fe Ratio on the Electrochemical Performance

The development of an efficient and cost-effective material is highly desirable for electrochemical devices such as electrolyzers and supercapacitors. Especially, pseudomorphic transformations of metal-organic frameworks (MOFs)/coordination polymers (CPs) into layered double hydroxides (LDHs) materials endow well-defined porosities, high surface area, exchangeable interlayer anions and easily adjustable electronic structure that are truly required for oxygen evolution reaction (OER) and high-performance supercapacitor applications. Herein, we have prepared NiFe-LDHs of various Ni/Fe ratios via a facile room-temperature alkaline hydrolysis of NiFe-CPs precursors. Electrochemical studies reveal that the catalyst having high amount of Fe (Ni1.2 Fe1 -LDH) showed the better OER activity with a low Tafel slope (65 mV dec-1 ) in 1 M KOH. On the other hand, the catalyst containing higher amount of Ni with better layered structure (Ni11.7 Fe1 -LDH) showed high performance for supercapacitor (702 F g-1 at 0.25 A g-1 ) in 3 M KOH. Moreover, a solid-state asymmetric supercapacitor device Ni11.7 Fe1 -LDH/AC was fabricated which exhibited a specific capacitance of 18 F g-1 at a current density of 1 A g-1 . The device displayed high cycling stability with 88% of capacitance retention after 7000 cycles. The experimental findings in this work will help in the futuristic development of NiFe-LDH based electrocatalysts for the enhanced electrochemical performances.

Insight into Electrochemical Performance of Nitrogen-Doped Carbon/NiCo-Alloy Active Nanocomposites

Nanocomposites containing Ni or Co or NiCo alloy and nitrogen-doped carbon with diverse ratios have been prepared and utilized as active elements in supercapacitors. The atomic contents of nitrogen, nickel, and cobalt have been adjusted by the supplement amount of Ni and Co salts. In virtue of the excellent surface groups and rich redox active sites, the NC/NiCo active materials exhibit superior electrochemical charge-storage performances. Among these as-prepared active electrode materials, the NC/NiCo1/1 electrode performs better than other bimetallic/carbon electrodes and pristine metal/carbon electrodes. Several characterization methods, kinetic analyses, and nitrogen-supplement strategies determine the specific reason for this phenomenon. As a result, the better performance can be ascribed to a combination of factors including the high surface area and nitrogen content, proper Co/Ni ratio, and relatively low average pore size. The NC/NiCo electrode delivers a maximum capacity of 300.5 C g^-1 and superior capacity retention of 92.30% after 3000 unceasing charge-discharge cycles. After assembling it into the battery-supercapacitor hybrid device, a high energy density of 26.6 Wh kg^-1 (at 412 W kg^-1 ) is achieved, comparable to the recent reports. Furthermore, this device can also power four light-emitting-diode (LED) demos, suggesting the potential practicability of these N-doped carbon compositing with bimetallic materials.

Electrochemical Sensing of Favipiravir with an Innovative Water-Dispersible Molecularly Imprinted Polymer Based on the Bimetallic Metal-Organic Framework: Comparison of Morphological Effects

Molecularly imprinted polymers (MIPs) are widely used as modifiers in electrochemical sensors due to their high sensitivity and promise of inexpensive mass manufacturing. Here, we propose and demonstrate a novel MIP-sensor that can measure the electrochemical activity of favipiravir (FAV) as an antiviral drug, thereby enabling quantification of the concentration of FAV in biological and river water samples and in real-time. MOF nanoparticles’ application with various shapes to determine FAV at nanomolar concentrations was described. Two different MOF nanoparticle shapes (dodecahedron and sheets) were systematically compared to evaluate the electrochemical performance of FAV. After carefully examining two different morphologies of MIP-Co-Ni@MOF, the nanosheet form showed a higher performance and efficiency than the nanododecahedron. When MIP-Co/Ni@MOF-based and NIP-Co/Ni@MOF electrodes (nanosheets) were used instead, the minimum target concentrations detected were 7.5 × 10−11 (MIP-Co-Ni@MOF) and 8.17 × 10−9 M (NIP-Co-Ni@MOF), respectively. This is a significant improvement (>102), which is assigned to the large active surface area and high fraction of surface atoms, increasing the amount of greater analyte adsorption during binding. Therefore, water-dispersible MIP-Co-Ni@MOF nanosheets were successfully applied for trace-level determination of FAV in biological and water samples. Our findings seem to provide useful guidance in the molecularly imprinted polymer design of MOF-based materials to help establish quantitative rules in designing MOF-based sensors for point of care (POC) systems.

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.

Electric-Field-Assisted Alkaline Hydrolysis of Metal-Organic Framework Bulk into Highly Porous Hydroxide for Energy Storage and Electrocatalysis

Metal-organic frameworks (MOFs) have attracted tremendous attention in the field of supercapacitors and electrocatalysis due to their open metal sites and high surface area. However, their inherent instability and poor electrical conductivity lead to limited electrochemical performance. Herein, we have employed a new and simple strategy for converting MOF bulk into porous Zn-Co hydroxide composites with the assistance of electric fields with different cycles. This method can alter the migration behavior of charged molecules/ions and improve the nucleation rate of hydroxide, thus adjusting the morphology of derivatives. As a supercapacitor electrode, the optimal material of Zn_0.3Co_0.7(OH)₂ with an electric-field application time of 1200 cycles shows excellent electrochemical performance with a high specific capacity of 981.2 C g^-1 at 1 A g^-1. Additionally, the fabricated asymmetric supercapacitor exhibits an energy density of 42.5 Wh kg^-1 at a power density of 750.0 W kg^-1 and a remarkable cycling stability (99% after 11,000 cycles). Simultaneously, the as-prepared Zn_0.3Co_0.7(OH)₂ with an electric-field application time of 1200 cycles delivers prominent OER performances, which can exhibit low overpotentials of 300 and 326 mV at 50 and 100 mA cm^-2, respectively, and shows a small Tafel slope of 31.5 mV dec^-1. This study represents a new strategy for the synthesis of economical and efficient electrode materials for supercapacitors and OER electrocatalysts and offers a novel way for the mild preparation of nanoderivatives from MOFs.

Cu/CuxO@C nanocomposites as efficient electrodes for high-performance supercapacitor devices

A novel method, reduction followed by oxidation procedure, has been developed to fabricate the efficient electrodes derivated from metal-organic frameworks (MOFs), which were synthesized using terephthalic acid (TP) or 1,3,5-benzenetricarboxylic...

Application of CoMn/CoFe layered double hydroxide based on metal-organic frameworks template to activate peroxymonosulfate for 2,4-dichlorophenol degradation

Metal-organic frameworks (MOFs) have unique properties and stable structures, which have been widely used as templates/precursors to prepare well developed pore structure and high specific surface area materials. In this article, an innovative and facile method of crystal reorganization was designed by using MOFs as sacrificial templates to prepare a layered double hydroxide (LDH) nano-layer sheet structure through a pseudomorphic conversion process under alkaline conditions. The obtained CoMn-LDH and CoFe-LDH catalysts broke the ligand of MOFs and reorganized the structure on the basis of retaining a high specific surface area and a large number of pores, which had higher specific surface area and well developed pore structure compared with LDH catalysts prepared by traditional methods, and thus provide more active sites to activate peroxymonosulfate (PMS). Due to the unique framework structure of MOFs, the MOF-derived CoMn-LDH and CoFe-LDH catalysts could provide more active sites to activate PMS, and achieve a 2,4-dichlorophenol degradation of 99.3% and 99.2% within 20 minutes, respectively. In addition the two LDH catalysts displayed excellent degradation performance for bisphenol A, ciprofloxacin and 2,4-dichlorophenoxyacetic acid (2,4-D). X-ray photoelectron spectroscopy indicated that the valence state transformation of metal elements participated in PMS activation. Electron paramagnetic resonance manifested that sulfate radical (SO₄^•-) and singlet oxygen (¹O₂) were the main species for degrading pollutants. In addition, after the three-cycle experiment, the CoMn-LDH and CoFe-LDH catalysts also showed long-term stability with a slight activity decrease in the third cycle. The phytotoxicity assessment determined by the germination of mung beans proved that PMS activation by MOF-derived LDH catalysts can basically eliminate the phytotoxicity of a 2,4-D solution. This research not only developed high-activity LDH catalysts for PMS activation, but also expanded the environmental applications of MOF derivants.

Synthesis of 3D flower-like hierarchical NiCo-LDH microspheres with boosted electrochemical performance for hybrid supercapacitors

3D flower-like NiCo-LDH microspheres synthesized via conformal alkaline hydrolysis strategy possess superior specific capacitance and stability, and the assembled HSC exhibits prominent power/energy density and durability.

Improved ionic diffusion and interfacial charge/mass transfer of ZIF-67-derived Ni–Co-LDH electrodes with bare ZIF-residual for enhanced supercapacitor performance

The crystallization of Ni–Co-LDH and the morphology of the hierarchical structure can be simply optimized to achieve improved ionic diffusion and reduce reaction resistance of charge/mass transfer between the electrode/electrolyte interfaces.

The Evolution in Electrochemical Performance of Honeycomb-Like Ni(OH)2 Derived from MOF Template with Morphology as a High-Performance Electrode Material for Supercapacitors

Ni(OH)2 derived from an MOF template was synthesized as an electrode material for supercapacitors. The electrochemical performance of the electrode was adjusted by effectively regulating the morphology of Ni(OH)2. The evolution of electrochemical performance of the electrode with morphology of Ni(OH)2 was highlighted in detail, based on which honeycomb-like Ni(OH)2 was successfully synthesized, and endowed the electrode with outstanding electrochemical performance. For the three-electrode testing system, honeycomb-like Ni(OH)2 exhibited a very high specific capacitance (1865 F·g-1 at 1 A·g-1, 1550 F·g-1 at 5 mV·s-1). Moreover, it also presented an excellent rate capability and cycling stability, due to 59.46 % of the initial value (1 A·g-1) being retained at 10 A·g-1, and 172% of initial value (first circle at 50 mV·s-1) being retained after 20,000 cycles. With respect to the assembled hybrid supercapacitor, honeycomb-like Ni(OH)2 also displayed superior electrochemical performance, with a high energy density (83.9 Wh·kg-1 at a power density of 374.8 W·kg-1). The outstanding electrochemical performance of Ni(OH)2 should be attributed to its unique honeycomb-like structure, with a very high specific surface area, which greatly accelerates the transformation and diffusion of active ions.

Bimetallic metal-organic frameworks and their derivatives

Bimetallic metal-organic frameworks (MOFs) have two different metal ions in the inorganic nodes. According to the metal distribution, the architecture of bimetallic MOFs can be classified into two main categories namely solid solution and core-shell structures. Various strategies have been developed to prepare bimetallic MOFs with controlled compositions and structures. Bimetallic MOFs show a synergistic effect and enhanced properties compared to their monometallic counterparts and have found many applications in the fields of gas adsorption, catalysis, energy storage and conversion, and luminescence sensing. Moreover, bimetallic MOFs can serve as excellent precursors/templates for the synthesis of functional nanomaterials with controlled sizes, compositions, and structures. Bimetallic MOF derivatives show exposed active sites, good stability and conductivity, enabling them to extend their applications to the catalysis of more challenging reactions and electrochemical energy storage and conversion. This review provides an overview of the significant advances in the development of bimetallic MOFs and their derivatives with special emphases on their preparation and applications.

Incorporating Ni-MOF structure with polypyrrole: enhanced capacitive behavior as electrode material for supercapacitor

Herein, Ni-MOF sheet incorporated with polypyrrole is fabricated via a simple wet-chemical approach, and the obtained PPy-MOF composite is investigated as an electrode material for supercapacitors. The composite is systematically investigated by a series of characterization studies including X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. Besides that, the electrochemical capacitive behaviors of the products are examined by electrochemical measurements. Electrochemical results show varying the ingredient ratio can lead to different electrocapacitive behavior, and PPy-MOF-0.2 is proved to possess the best performance in the investigated recipes. Furthermore, an asymmetric supercapacitor employing PPy-MOF and activated carbon as positive and negative electrodes is also assembled, which exhibits high energy density.

Wideband saturable absorption in metal-organic frameworks (MOFs) for mode-locking Er- and Tm-doped fiber lasers

We fabricate a metal-organic framework (MOF) saturable absorber (SA) based on a microfiber. Nonlinear optical absorption of the MOF SA is characterized systematically. The modulation depth is found to be 6.57% and 14.25% at 1.5 and 2 μm spectral ranges, respectively. We report ultrashort pulse generation in both Er- and Tm-doped fiber lasers by using the same microfiber-based MOF SA, operating at 384 fs and 1.3 ps pulse duration at 1563 nm and 1882 nm, respectively. To the best of our knowledge, this is the first report of a MOF-based fiber laser at near infrared spectral ranges. Our findings validate the applicability of MOFs as a broadband SA in ultrafast photonics.

Nitrogen-doped carbon integrated nickel–cobalt metal phosphide marigold flowers as a high capacity electrode for hybrid supercapacitors

The fabrication of advanced MOF-derived multicomponent NiCoP/NC marigold flowers electrode for high-performance hybrid supercapacitors.

"HOT" Alkaline Hydrolysis of Amorphous MOF Microspheres to Produce Ultrastable Bimetal Hydroxide Electrode with Boosted Cycling Stability

Nickel/cobalt hydroxide is a promising battery-type electrode material for supercapacitors. However, its low cycle stability hinders further applications. Herein, Ni_0.7 Co_0.3 (OH)₂ core-shell microspheres exhibiting extreme-prolonged cycling life are successfully synthesized, employing Ni-Co-metal-organic framework (MOF) as the precursor/template and a specific hydrolysis strategy. The Ni-Co-MOF and KOH aqueous solution are separated and heated to 120 °C before mixing, rather than mixing before heating. Through this hydrolysis strategy, no MOF residual exists in the product, contributing to close stacking of the hydroxide nanoflakes to generate Ni_0.7 Co_0.3 (OH)₂ microspheres with a robust core-shell structure. The electrode material exhibits high specific capacity (945 C g^-1 at 0.5 A g^-1 ) and unprecedented cycling performance (100% after 10 000 cycles). The fabricated asymmetric supercapacitor delivers an energy density of 40.14 Wh kg^-1 at a power density of 400.56 W kg^-1 and excellent cycling stability (100% after 20 000 cycles). As far as is known, it is the best cycling performance for pure Ni/Co(OH)₂ .

Dual Functionalized CuMOF-Based Composite for High-Performance Supercapacitors

Herein, we utilized our previously reported highly porous CuMOF, {[Cu₂(L)(H₂O)₂]·(5DMF)·(4H₂O)}_n, decorated with amine and trifluoromethyl functional groups for energy storage application. This robust framework in CuMOF enhances the chemical and thermal stabilities as well as improves the interfacial binding interactions. The poor conductivity of CuMOF usually restricts its practical utility in energy storage systems, due to which rGO was introduced along with CuMOF to form a CuMOF/rGO composite (1) through a facile ultrasonication technique. The synergistic effects between CuMOF and rGO induce a dramatic enhancement in specific capacitance (462 F g^-1 at 0.8 A g^-1) of 1 with a cycle life of 93.75% up to 1000 cycles. The results highlight 1 as an emerging contestant for next generation supercapacitors.

Controlled Hydrolysis of Metal-Organic Frameworks: Hierarchical Ni/Co-Layered Double Hydroxide Microspheres for High-Performance Supercapacitors

Pseudomorphic conversion of metal-organic frameworks (MOFs) enables the fabrication of nanomaterials with well-defined porosities and morphologies for enhanced performances. However, the commonly reported calcination strategy usually requires high temperature to pyrolyze MOF particles and often results in uncontrolled growth of nanomaterials. Herein, we report the controlled alkaline hydrolysis of MOFs to produce layered double hydroxide (LDH) while maintaining the porosity and morphology of MOF particles. The preformed trinuclear M₃(μ₃-OH) (M = Ni²⁺ and Co²⁺) clusters in MOFs were demonstrated to be critical for the pseudomorphic transformation process. An isotopic tracing experiment revealed that the ¹⁸O-labeled M₃(μ₃-¹⁸OH) participated in the structural assembly of LDH, which avoided the leaching of metal cations and the subsequent uncontrolled growth of hydroxides. The resulting LDHs maintain the spherical morphology of MOF templates and possess a hierarchical porous structure with high surface area (BET surface area up to 201 m²·g^-1), which is suitable for supercapacitor applications. As supercapacitor electrodes, the optimized LDH with the Ni:Co molar ratio of 7:3 shows a high specific capacitance (1652 F·g^-1 at 1 A·g^-1) and decent cycling performance, retaining almost 100% after 2000 cycles. Furthermore, the hydrolysis method allows the recycling of organic ligands and large-scale synthesis of LDH materials.

Temperature controlled diffusion of hydroxide ions in 1D channels of Ni-MOF-74 for its complete conformal hydrolysis to hierarchical Ni(OH)2 supercapacitor electrodes

Conformal hydrolysis of MOF precursors is a promising strategy to prepare hierarchical metal hydroxide electrode materials on a large scale with low cost and high efficiency. However, a complete transformation is challenging due to the normal "outside-in" conversion process. After studying the hydrolysis of Ni-MOF-74, which has regular 1D channels, we suggest that the transformation to Ni(OH)2 can occur simultaneously outside and within the precursor depending on the treatment temperature. Molecular dynamics simulations reveal that a higher temperature weakens the steric effects of OH- ions and facilitates the diffusion in the regular channels, and therefore, a complete transformation from Ni-MOF-74 to Ni(OH)2 is achieved. It is for the first time demonstrated that the 1D channels of MOFs are utilized for the complete conformal hydrolysis of Ni-MOF-74 to Ni(OH)2 electrode materials. Meanwhile, we also perform pioneering work illustrating that the complete conformal hydrolysis is the key to the improved supercapacitor performances of the MOF-derived Ni(OH)2 electrodes. The prepared Ni(OH)2 electrode under the optimized conditions has a specific capacity of 713.2 C g-1 at a current density of 1 A g-1, which is at least 28% larger than those of the Ni(OH)2 prepared at other temperatures. The detailed analyses based on CV and EIS of the obtained Ni(OH)2 electrodes indicate that the residual MOFs within electrodes due to incomplete hydrolysis significantly influence the diffusion length and diffusion efficiency of OH-, drastically lowering the supercapacitor performances.

Terephthalic acid induced binder-free NiCoP–carbon nanocomposite for highly efficient electrocatalysis of hydrogen evolution reaction

NiCoP–carbon nanocomposite based electrocatalyst (NiCoP–C(TPA)/NF) for highly efficient hydrogen production in the water electrolysis process was developed for the first time by a terephthalic acid induced binder-free method.

Effect of the cobalt and zinc ratio on the preparation of zeolitic imidazole frameworks (ZIFs): synthesis, characterization and supercapacitor applications

The effect of the cobalt nitrate hexahydrate/zinc nitrate hexahydrate molar ratio on the physicochemical features of the zeolitic imidazole framework (ZIF) was studied.

Dandelion-like nickel/cobalt metal-organic framework based electrode materials for high performance supercapacitors

Metal-organic frameworks (MOFs), serving as a promising electrode material in the supercapacitors, have attracted tremendous interests in recent years. Here, through modifying the molar ratio of the Ni²⁺ and Co²⁺, we have successfully fabricated Ni-MOF and Ni/Co-MOF by a facile hydrothermal method. The Ni/Co-MOF with a dandelion-like hollow structure shows an excellent specific capacitance of 758 F g^-1 at 1 A g^-1 in the three-electrode system. Comparing with Ni-MOF, the obtained Ni/Co-MOF has a better rate capacitance (89% retention at 10 A g^-1) and cycling life (75% retention after 5000 circulations). Besides, the assembled asymmetric supercapacitor based on Ni/Co-MOF and active carbon exhibits a high specific energy density of 20.9 W h kg^-1 at the power density of 800 W kg^-1. All these results demonstrate that the mixed-metal strategy is an effective way to optimize the morphology and improve the electrochemical property of the MOFs.

Co/CoOx Nanoparticles Embedded on Carbon for Efficient Catalysis of Oxygen Evolution and Oxygen Reduction Reactions

The oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are important electrochemical reactions to realize clean energy technologies. Herein, we prepared a hybrid electrocatalyst consisting of Co/CoO_x nanoparticles embedded in amorphous carbon through the simple pyrolysis of cobalt-based zeolitic terephthalate frameworks. The pyrolysis temperature significantly influenced the structure morphology and catalytic behavior. Good contact between Co/CoO_x and amorphous carbon resulted in a high catalytic efficiency. The hybrid obtained under pyrolysis temperature of 600 °C exhibited the highest performance for OER, offering a stable current density of 10 mA cm^-2 at 277 mV in basic media. Besides good OER behavior, it also showed good ORR performance [onset potential: ∼0.87 V vs. the reversible hydrogen electrode (RHE), diffusion-limiting current density: ∼4.9 mA cm^-2 ]. This work describes a novel and efficient catalyst, and greatly expands the scope of low-cost Co-based electrocatalysts for various electrochemical reactions without the need for N-containing ligands.

Interpenetrated and Polythreaded CoII-Organic Frameworks as a Supercapacitor Electrode Material with Ultrahigh Capacity and Excellent Energy Delivery Efficiency

Synthesizing kinetically stable coordination polymers (CPs) through ligand functionalization can effectively improve their supercapacitive performances. Herein, we have successfully synthesized three novel and topological Co-CPs by varying the flexible N-donor ligand and inorganic anions, namely, interpenetrated [Co(HTATB)( o-bib)]·H₂O, extended two-dimensional (2D) layered Co(HTATB)( m-bib)·2H₂O, and three-dimensional (3D) Co(HTATB)( m-bib), where bib is the flexible N-donor bis((1 H-imidazol-1-yl)methyl)benzene linker (where o- and m- refer to ortho and meta positions, respectively) ligand and HTATB is the partial deprotonation mode from 4,4',4″- s-triazine-2,4,6-triyl-tribenzoic acid. Various Co-CPs have been directly applied in the field of supercapacitors. All these framework materials exhibit high capacitance, excellent energy delivery efficiency, and good cycling performance. For instance, the maximum specific capacitance for penetrated 3D networks is 2572 F g^-1 at 2.0 A g^-1, and the mean energy delivery efficiency is up to 92.7% based on the tested current densities. Compared with extensional 2D layered and 3D networks, the 3D interpenetrated and polythreaded architectures could provide more active sites and thus promote fast charging and discharging processes. Furthermore, the Li⁺ uptake-release abilities of the Co-based CPs are also investigated, and the initial discharge capacity value for the 3D interpenetrated structures can reach up to 1792 mA h g^-1 at a current density of 50 mA g^-1.

Optimizing crystallinity and porosity of hierarchical Ni(OH)2 through conformal transformation of metal–organic framework template for supercapacitor applications

Conformal hydrolysis of MOFs (metal–organic frameworks) yields high-performance supercapacitor electrodes.

Interpenetrated nano-MOFs for ultrahigh-performance supercapacitors and excellent dye adsorption performance

Designing and preparing kinetically stable metal–organic frameworks through ligand functionalization can effectively improve their supercapacitive performances.

Fluorine Doping Strengthens the Lithium-Storage Properties of the Mn-Based Metal-Organic Framework

The electrochemical properties of the metal-organic framework (MOF)-based composite as electrode material can be significantly improved by means of partial destruction of the full coordination of linkers to metal ions and replacing with other small ions, which make metal centers become more accostable and consequently more effective for the lithiation/delithiation process. In this paper, F^- was chosen to replace some of the benzenedicarboxylate (BDC) linkers because of its better interaction with the Li⁺ than the oxide ion. What's more, the formed M-F bond promotes the Li⁺ to transfer at the active material interface and protects the surface from HF attacking. The as-synthesized F-doped Mn-MOF electrode maintains a reversible capacity of 927 mA h g^-1 with capacity retention of 78.5% after 100 cycles at 100 mA g^-1 and also exhibits a high discharge capacity of 716 mA h g^-1 at 300 mA g^-1 and 620 mA h g^-1 at 500 mA g^-1 after 500 cycles. Even at 1000 mA g^-1, the electrode still maintains a high reversible capacity of 494 mA h g^-1 after 500 cycles as well as a Coulombic efficiency of nearly 100%, which is drastically increased compared with pure Mn-MOF material as expected.

Recent Progress in Metal-Organic Frameworks and Their Derived Nanostructures for Energy and Environmental Applications

Metal-organic frameworks (MOFs), as a very promising category of porous materials, have attracted increasing interest from research communities due to their extremely high surface areas, diverse nanostructures, and unique properties. In recent years, there is a growing body of evidence to indicate that MOFs can function as ideal templates to prepare various nanostructured materials for energy and environmental cleaning applications. Recent progress in the design and synthesis of MOFs and MOF-derived nanomaterials for particular applications in lithium-ion batteries, sodium-ion batteries, supercapacitors, dye-sensitized solar cells, and heavy-metal-ion detection and removal is reviewed herein. In addition, the remaining major challenges in the above fields are discussed and some perspectives for future research efforts in the development of MOFs are also provided.