Three-dimensional graphene/metal-organic framework composites for electrochemical energy storage and conversion

Three-dimensional graphene (3DG)/metal-organic framework (MOF)-based composites have attracted more and more attention in the field of energy due to their unique hierarchical porous structure and properties. The combination of graphene with MOFs can not only effectively overcome the limitations of poor electrical conductivity and low stability of MOFs, but also prevent the aggregation and reaccumulation between graphene sheets. Moreover, 3DG/MOF composites can also be used as multifunctional precursors with adjustable structures and composition of derivatives, thus expanding their applications in the field of electrochemistry. This feature article elaborates the latest synthesis methods of 3DG/MOF composites and their derivatives, along with their applications in batteries, supercapacitors (SCs) and electrocatalysis. In addition, the current challenges and future prospects of 3DG/MOF-based composites are discussed.

Hierarchical porous metal–organic gels and derived materials: from fundamentals to potential applications

This review summarizes recent progress in the development and applications of metal–organic gels (MOGs) and their hybrids and derivatives dividing them into subclasses and discussing their synthesis, design and structure–property relationship.

Multifunctional AIEgen-based luminescent metal–organic frameworks with coordination-induced emission for chemical sensing

Aggregation-induced emission luminogens (AIEgens) offer a timely remedy to tackle aggregation-caused quenching of traditional organic fluorescence probes.

Review on carbonaceous materials and metal composites in deformable electrodes for flexible lithium-ion batteries

With the rapid propagation of flexible electronic devices, flexible lithium-ion batteries (FLIBs) are emerging as the most promising energy supplier among all of the energy storage devices owing to their high energy and power densities with good cycling stability. As a key component of FLIBs, to date, researchers have tried to develop newly designed high-performance electrochemically and mechanically stable pliable electrodes. To synthesize better quality flexible electrodes, based on high conductivity and mechanical strength of carbonaceous materials and metals, several research studies have been conducted. Despite both materials-based electrodes demonstrating excellent electrochemical and mechanical performances in the laboratory experimental process, they cannot meet the expected demands of stable flexible electrodes with high energy density. After all, various significant issues associated with them need to be overcome, for instance, poor electrochemical performance, the rapid decay of the electrode architecture during deformation, and complicated as well as costly production processes thus limiting their expansive applications. Herein, the recent progression in the exploration of carbonaceous materials and metals based flexible electrode materials are summarized and discussed, with special focus on determining their relative electrochemical performance and structural stability based on recent advancement. Major factors for the future advancement of FLIBs in this field are also discussed.

Ultrafast and durable Li/Na storage by an iron selenide anode using an elastic hierarchical structure

An exquisite composite consisting of polycystic FeSe/C microspheres encapsulated within a three-dimensional graphene framework was designed and fabricated for fast and durable Li-/Na-storage applications.

A Robust Strategy for Engineering Fe7S8/C Hybrid Nanocages Reinforced by Defect-Rich MoS2 Nanosheets for Superior Potassium-Ion Storage

Metal sulfides have attracted tremendous research interest for developing high-performance electrodes for potassium-ion batteries (PIBs) for their high theoretical capacities. Nevertheless, the practical application of metal sulfides in PIBs is still unaddressed due to their intrinsic shortcomings of low conductivity and severe volume changes during the potassiation/depotassiation process. Herein, robust Fe₇S₈/C hybrid nanocages reinforced by defect-rich MoS₂ nanosheets (Fe₇S₈/C@d-MoS₂) were designed, which possess abundant multichannel and active sites for potassium-ion transportation and storage. Kinetic analysis and theoretical calculation verify that the introduction of defect-rich MoS₂ nanosheets dramatically promotes the potassium-ion diffusion coefficient. The ex-situ measurements revealed the potassium-ion storage mechanism in the Fe₇S₈/C@d-MoS₂ composite. Benefitting from the tailored structural design, the Fe₇S₈/C@d-MoS₂ hybrid nanocages show high reversible capacity, exceptional rate property, and superior cyclability.

MOF-derived ultrasmall CoSe2 nanoparticles encapsulated by an N-doped carbon matrix and their superior lithium/sodium storage properties

Ultrasmall CoSe₂ nanoparticles encapsulated by an N-doped carbon matrix were prepared by selenizing a novel Co-metal organic framework precursor. The excellent electrochemical performance may be due to the synergistic effect of the N-doped carbon matrix and the ultrasmall CoSe₂.

Tailoring Coral-Like Fe7Se8@C for Superior Low-Temperature Li/Na-Ion Half/Full Batteries: Synthesis, Structure, and DFT Studies

The intrinsic charge-transfer property bears the primary responsibility for the sluggish redox kinetics of the common electrode materials, especially operated at low temperatures. Herein, we report the crafting of homogeneously confined Fe₇Se₈ nanoparticles with a well-defined graphitic carbon matrix that demonstrate a highly efficient charge-transfer system in a designed natural coral-like structure (cl-Fe₇Se₈@C). Notably, the intricate architecture as well as highly conductive peculiarity of C concurrently satisfy the demands of achieving fast ionic/electrical conductivities for both Li/Na-ion batteries in a wide temperature range. For example, when cl-Fe₇Se₈@C is employed as the anode material to assemble full batteries with the cathode of Na₃V₂(PO₄)₂O₂F (NVPOF), decent capacities of 323.1 and 175.9 mA h g^-1 can be acquired at temperatures of 25 and -25 °C, respectively. This work is significant for further developing potential anode materials for advanced energy storage and conversion under low-temperature conditions.

In Situ Fabrication of Carbon-Encapsulated Fe7X8 (X = S, Se) for Enhanced Sodium Storage

Sodium-ion batteries (SIBs) have been regarded as a promising alternative to lithium-ion batteries due to the natural abundance of sodium in the earth's crust. In our work, fusiform Fe₇X₈@C (X = S, Se) composites were obtained via a one-step pyrolysis strategy applied to SIB anode materials. The formed carbon skeleton could prevent the Fe₇X₈ nanoparticles from agglomeration and stabilize the interface of Fe/Na₂X generated in the redox reactions. Fe₇X₈@C (X = S, Se) exhibits excellent reversible specific capacity (1005.3 mAh g^-1 under 0.2 A g^-1 for Fe₇S₈@C and 458.5 mAh g^-1 under 0.5 A g^-1 for Fe₇Se₈@C), outstanding rate performance (654.7 mAh g^-1 for Fe₇S₈@C and 392.9 mAh g^-1 for Fe₇Se₈@C going through 300 loops even under 2 A g^-1), and excellent cycling properties (795.8 mAh g^-1 after 50 loops under 0.2 A g^-1 for Fe7S₈@C and 399.9 mAh g^-1 going through 150 loops under 0.5 A g^-1 for Fe₇Se₈@C). The excellent electrochemical performance of Fe₇X₈@C composites makes them promising anode materials for SIBs.

Applications of Metal-Organic-Framework-Derived Carbon Materials

Carbon materials derived from metal-organic frameworks (MOFs) have attracted much attention in the field of scientific research in recent years because of their advantages of excellent electron conductivity, high porosity, and diverse applications. Tremendous efforts are devoted to improving their chemical and physical properties, including optimizing the morphology and structure of the carbon materials, compositing them with other materials, and so on. Here, many kinds of carbon materials derived from metal-organic frameworks are introduced with a particular focus on their promising applications in batteries (lithium-ion batteries, lithium-sulfur batteries, and sodium-ion batteries), supercapacitors (metal oxide/carbon and metal sulfide/carbon), electrocatalytic reactions (oxygen reduction reaction, oxygen evolution reaction, and hydrogen evolution reaction), water treatment (MOF-derived carbon and other techniques), and other possible fields. To close, some existing problem and corresponding possible solutions are proposed based on academic knowledge from the reported literature, along with a great deal of experimental experience.

Synchronous synthesis of Kirkendall effect induced hollow FeSe2/C nanospheres as anodes for high performance sodium ion batteries

Facilely synthesized Kirkendall effect induced hollow FeSe₂/C nanospheres exhibit excellent electrochemical performance as an anode for sodium ion batteries.

MOF-derived nanohybrids for electrocatalysis and energy storage: current status and perspectives

Metal–organic frameworks can be easily transformed to nanohybrids that are exceptionally good active materials for both electrocatalysis and energy storage. We review the latest developments in this area.