Unveiling the scope and perspectives of MOF-derived materials for cutting-edge applications

Although synthesis and design of MOFs are crucial factors to the successful implementation of targeted applications, there is still lack of knowledge among researchers about the synthesis of MOFs and their derived composites for practical applications. For example, many researchers manipulate study results, and it has become quite difficult to quit this habit specifically among the young researchers Undoubtedly, MOFs have become an excellent class of compounds but there are many challenges associated with their improvement to attain diverse applications. It has been noted that MOF-derived materials have gained considerable interest owing to their unique chemical properties. These compounds have exhibited excellent potential in various sectors such as energy, catalysis, sensing and environmental applications. It is worth mentioning that most of the researchers rely on commercially available MOFs for use as precursor supports, but it is an unethical and wrong practice because it prevents the exploration of the hidden diversity of similar materials. The reported studies have significant gaps and flaws, they do not have enough details about the exact parameters used for the synthesis of MOFs and their derived materials. For example, many young researchers claim that MOF-based materials cannot be synthesized as per the reported instructions for large-scale implementation. In this regard, current article provides a comprehensive review of the most recent advancements in the design of MOF-derived materials. The methodologies and applications have been evaluated together with their advantages and drawbacks. Additionally, this review suggests important precautions and solutions to overcome the drawbacks associated with their preparation. Applications of MOF-derived materials in the fields of energy, catalysis, sensing and environment have been discussed. No doubt, these materials have become excellent class but there are still many challenges ahead to specify it for the targeted applications.

Microwave-mediated synthesis of tetragonal Mn3O4 nanostructure for supercapacitor application

The development of electrode materials plays a vital role in energy storage applications to save and store energy. In the present work, the synthesis of nanorod shaped Mn₃O₄ supported with amorphous carbon (Mn₃O₄/AC) is reported by the microwave method for supercapacitor application. The as-prepared electrode material was then characterized using microscopic and spectroscopic techniques. The electrochemical supercapacitor performance of Mn₃O₄/AC was examined by the cyclic voltammetry and galvanostatic charge-discharge method inside the three-electrode assembly cell. The results showed that the Mn₃O₄/AC delivers the excellent capacitance value of the 569.5 Fg^-1 at the current load of 1 Ag^-1, higher than the previously reported Mn₃O₄ based electrodes. The better performance of the Mn₃O₄/AC is credited to the excellent redox behaviour of the Mn₃O₄ and the presence of the amorphous carbon, which facilitated the fast ion interaction between the electrode and electrolyte during the electrochemical reaction.

Recent progress on pristine two-dimensional metal-organic frameworks as active components in supercapacitors

Two-dimensional (2D) metal-organic frameworks (MOFs) are a new generation of 2D materials that can provide uniform active sites and unique open channels as well as excellent catalytic abilities, interesting magnetic properties, and reasonable electrical conductivities. Thus, these MOFs are uniquely qualified for use in applications in energy-related fields or portable devices because they possess fast charge and discharge ability, high power density, and ultralong cycle life factors. There has been worldwide research interest in 2D conducting MOFs, and numerous techniques and strategies have been developed to synthesize these MOFs and their derivatives. Thus, this is the opportune time to review recent research progress on the development of 2D MOFs as electrodes in supercapacitors. This review covers synthetic design strategies, electrochemical performances, and working mechanisms. We will divide these 2D MOFs into two types on the basis of their conductive aspects: 2D conductive MOFs and 2D layered MOFs (including pillar-layered MOFs and 2D nanosheets). The challenges and perspectives of 2D MOFs are also provided.

Metal–organic frameworks with different spatial dimensions for supercapacitors

Recent progress in MOF materials for SCs with different spatial dimensions, such as 2D MOFs, including conductive MOFs and nanosheets, and 3D MOFs, categorized as single metallic and multiple metallic MOFs, are reviewed.

Molten-Salt-Assisted Synthesis of Hierarchical Porous MnO@Biocarbon Composites as Promising Electrode Materials for Supercapacitors and Lithium-Ion Batteries

Biomass-derived carbon composites (e.g., metal oxide/biocarbon) have been used as promising electrode materials for energy storage devices owing to their natural abundance and simple preparation process. However, low loading content/inhomogeneous distribution of metal oxides and inefficient cracking of biocarbon (BC) are intractable obstacles that impede the efficient utilization of biomass. In this work, hierarchical porous MnO/BC composites were prepared by a facile molten-salt-assisted strategy based on the superior salt-water absorption ability of agaric. The addition of NaCl induces a liquid reaction medium by formation of a molten salt mixture at high temperature to effectively realize the activation and cracking of the bulk carbon, and it also acts as a recyclable sacrificial template to form mesopores and macropores in the as-prepared hierarchical porous MnO/BC composites. The highly porous and uniform BC framework effectively enhances ion diffusion and electron-transfer ability, serves as a protective layer to prevent fracturing and agglomeration of MnO, and thus enables superior rate performance and cycling stability of the MnO/BC composite for both supercapacitor electrodes (94 % capacity retention at 20 mA cm^-2 after 5000 cycles) and lithium-ion battery anodes (783 mA h g^-1 after 1000 cycles). Notably, considering the simple and low-cost preparation process, this work opens a promising avenue for the large-scale production of advanced metal oxide/BC hybrid electrode materials for electrochemical energy storage.

Controllable synthesis and electrochemical capacitor performance of MOF-derived MnOx/N-doped carbon/MnO2 composites

Different amount of carbon and nitrogen, for MOF-derived nitrogen-doped carbon/Mn₃O₄ composites, can result in the discrepancies of synergistic effect which plays an important role in final electrochemical performance.

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.

Controllable vapor phase fabrication of F:Mn3O4thin films functionalized with Ag and TiO2

The first example of vapor phase fabrication of Mn₃O₄(hausmannite) thin films chemically modified with fluorine and functionalized with Ag and TiO₂, resulting in high purity composites with an intimate constituent contact.

Molecular Engineering of MnII Diamine Diketonate Precursors for the Vapor Deposition of Manganese Oxide Nanostructures

Molecular engineering of manganese(II) diamine diketonate precursors is a key issue for their use in the vapor deposition of manganese oxide materials. Herein, two closely related β-diketonate diamine Mn^II adducts with different fluorine contents in the diketonate ligands are examined. The target compounds were synthesized by a simple procedure and, for the first time, thoroughly characterized by a joint experimental-theoretical approach, to understand the influence of the ligand on their structures, electronic properties, thermal behavior, and reactivity. The target compounds are monomeric and exhibit a pseudo-octahedral coordination of the Mn^II centers, with differences in their structure and fragmentation processes related to the ligand nature. Both complexes can be readily vaporized without premature side decompositions, a favorable feature for their use as precursors for chemical vapor deposition (CVD) or atomic layer deposition applications. Preliminary CVD experiments at moderate growth temperatures enabled the fabrication of high-purity, single-phase Mn₃ O₄ nanosystems with tailored morphology, which hold great promise for various technological applications.

Materials Design and System Construction for Conventional and New-Concept Supercapacitors

With the development of renewable energy and electrified transportation, electrochemical energy storage will be more urgent in the future. Supercapacitors have received extensive attention due to their high power density, fast charge and discharge rates, and long-term cycling stability. During past five years, supercapacitors have been boomed benefited from the development of nanostructured materials synthesis and the promoted innovation of devices construction. In this review, we have summarized the current state-of-the-art development on the fabrication of high-performance supercapacitors. From the electrode material perspective, a variety of materials have been explored for advanced electrode materials with smart material-design strategies such as carbonaceous materials, metal compounds and conducting polymers. Proper nanostructures are engineered to provide sufficient electroactive sites and enhance the kinetics of ion and electron transport. Besides, new-concept supercapacitors have been developed for practical application. Microsupercapacitors and fiber supercapacitors have been explored for portable and compact electronic devices. Subsequently, we have introduced Li-/Na-ion supercapacitors composed of battery-type electrodes and capacitor-type electrode. Integrated energy devices are also explored by incorporating supercapacitors with energy conversion systems for sustainable energy storage. In brief, this review provides a comprehensive summary of recent progress on electrode materials design and burgeoning devices constructions for high-performance supercapacitors.

Nano Metal-Organic Framework-Derived Inorganic Hybrid Nanomaterials: Synthetic Strategies and Applications

Nano- (or micro-scale) metal-organic frameworks (NMOFs), also known as coordination polymer particles (CPPs), have received much attention because of their structural diversities and tunable properties. Besides the direct use, NMOFs can be alternatively used as sacrificial templates/precursors for the preparation of a wide range of hybrid inorganic nanomaterials in straightforward and controllable manners. Distinct advantages of using NMOF templates are correlated to their structural and functional tailorability at molecular levels that is rarely acquired in any other conventional template/precursor. In addition, NMOF-derived inorganic nanomaterials with distinct chemical and physical properties are inferred to dramatically expand the scope of their utilization in many fields. In this review, we aim to provide readers with a comprehensive summary of recent progress in terms of synthetic approaches for the production of diverse inorganic hybrid nanostructures from as-synthesized NMOFs and their promising applications.

High nitrogen-doped carbon/Mn3O4 hybrids synthesized from nitrogen-rich coordination polymer particles as supercapacitor electrodes

High nitrogen-doped carbon/Mn3O4 composites were synthesized by annealing nitrogen-rich Mn-based coordination polymer particles, and investigated by electron microscopy, X-ray diffraction, and electrochemical experiments. To assess the performance of high nitrogen-doped hybrids as electrode materials in supercapacitors, cyclic voltammetry and galvanostatic charging-discharging measurements are performed. High nitrogen-doped carbon/Mn3O4 composites are charged and discharged faster and have higher capacitance than carbon/Mn3O4 nanostructures with low nitrogen amounts and other reported ones. The capacitance of the high nitrogen-doped carbon/Mn3O4 is 94% retained after 1000 cycles at a constant current. These improvements can be attributed to the nitrogen-doped carbon matrix, which promotes fast Faradaic charging and discharging of the Mn3O4 motifs. The nitrogen-doped carbon/Mn3O4 composites could be a promising candidate material for a high-capacity, low-cost, and environmentally friendly electrode for supercapacitors.

Designed two-step morphological transformation: a new strategy to synthesize uniform metalloporphyrin-containing coordination polymer particles

Uniform metalloporphyrin-containing coordination polymer particles were synthesized from seed structures by designed two-step morphological transformation.

In situ fabrication of graphene decorated microstructured globe artichokes of partial molar nickel cobaltite anchored on a Ni foam as a high-performance supercapacitor electrode

3D microstructured globe artichokes of a rGO/Ni_0.3Co_2.7O₄ composite were synthesized through a hydrothermal method to contribute an efficient work nature as supercapacitor electrodes.

Temperature-dependent self-assembly of NiO/Co3O4 composites for supercapacitor electrodes with good cycling performance: from nanoparticles to nanorod arrays

Temperature-dependent and uniform NiO/Co₃O₄ composites have been presented, which show high specific capacitances and good cycling performances even at high current densities.

Controllable fabrication of multifunctional 1D Ag-based coordination polymer@PVP nanowires

The composite Ag-based coordination polymer@PVP nanowires have been mildly synthesized in the presence of PVP, which may be potentially applied in anticancer and antibacterial fields.

Solid-state grinding/low-temperature calcining synthesis of carbon coated MnO2 nanorods and their electrochemical capacitive property

Carbon-coated MnO₂ nanorods, prepared using a solid-state grinding/low-temperature calcining synthesis method, exhibit excellent capacitive performance and long-term cycling stability.

Preparation of size-selective Mn3O4 hexagonal nanoplates with superior electrochemical properties for pseudocapacitors

Regular Mn₃O₄ hexagonal nanoplates are synthesized for a supercapacitor electrode. This electrode exhibits excellent cycling stability with 100% capacity retention after 5000 cycles.

One-dimensional ZnO/Mn3O4 core/shell nanorod and nanotube arrays with high supercapacitive performance for electrochemical energy storage

A facile electrochemical method to prepare one-dimensional ZnO/Mn₃O₄ core/shell nanorod and nanotube arrays is reported and their applications as electrodes in supercapacitors are examined. The as-prepated ZnO/Mn₃O₄ core/shell nanoarray structures exhibit excellent capacitance and superior rate performance.