Ni-based metal organic frameworks (Ni-MOFs) with unique hierarchical hollow ball-in-ball nanostructure were synthesized by solvothermal reactions. After successive carbonization and oxidation treatments, hierarchical NiO/Ni nanocrystals covered with a graphene shell were obtained with the hollow ball-in-ball nanostructure intact. The resulting materials exhibited superior performance as the anode in lithium ion batteries (LIBs): they provide high reversible specific capacity (1144 mAh/g), excellent cyclability (nearly no capacity loss after 1000 cycles) and rate performance (805 mAh/g at 15 A/g). In addition, the hierarchical NiO/Ni/Graphene composites demonstrated promising performance as anode materials for sodium-ion batteries (SIBs). Such a superior lithium and sodium storage performance is derived from the well-designed hierarchical hollow ball-in-ball structure of NiO/Ni/Graphene composites, which not only mitigates the volume expansion of NiO during the cycles but also provides a continuous highly conductive graphene matrix to facilitate the fast charge transfer and form a stable SEI layer.

Metal Organic Frameworks Derived Hierarchical Hollow NiO/Ni/Graphene Composites for Lithium and Sodium Storage

https://doi.org/10.1016/j.xinn.2022.100281

Metal-organic framework nanocrystal-derived hollow porous materials: Synthetic strategies and emerging applications

Metal organic frameworks (MOFs) have been widely researched and applied in many fields. However, the poor electrical conductivity of many traditional MOFs greatly limits their application in electrochemistry, especially in energy storage. Benefited from the full charge delocalization in the atomical plane, conductive MOFs (c-MOFs) exhibit good electrochemical performance. Besides, unlike graphene, c-MOFs are provided with 1D cylindrical channels, which can facilitate the ion transport and enable high ion conductivity. Transition-metal oxides (TMOs) are promising materials with good electrochemical energy storage performance due to their excellent oxidation-reduction activity. When composited with TMOs, the c-MOFs can significantly improve the capacitance and rate performance. In this work, for the first time, we designed serial MnO2@Ni-HHTP (HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene) nanoarrays with different lengths and explored how the lengths influence the electrochemical energy storage performance. By taking advantage of the high redox activity of MnO2 and the excellent electron and ion conductivity in Ni-HHTP, when assembled as the positive electrode material in an aqueous asymmetric supercapacitor, the device displays high energy density, outstanding rate performance, and superior cycle stability. We believe that the results of this work would provide a good prospect for developing other c-MOF composites as a potential class of electrode materials in energy storage and conversion.

When Conductive MOFs Meet MnO2: High Electrochemical Energy Storage Performance in an Aqueous Asymmetric Supercapacitor.

Fabrication of hollow MnFe2O4 nanocubes assembled by CoS2 nanosheets for hybrid supercapacitors

Metal organic frameworks (MOFs) are hybrid materials built with both organic and inorganic components. The potential of these structures was highlighted in the 1990s and since then, over 90 000 articles dealing with MOFs have been published (still growing rapidly), demonstrating a wide variety of applications. However, an improvement in the electrochemical properties of MOFs is still required to enhance the attributes to satisfy the real and strategic applications of MOF-electrode materials in energy conversion and storage (batteries, supercapacitors, and as catalysts for fuel cells and water splitting), especially in the development of electrochemical sensors. In this sense, being the focus of this review, the great potential of MOF-derived structures for the construction of electrochemical sensors is presented, highlighting the recent advances and strategies on MOF-derived materials, such as metals, metal oxide/hydroxide, metal sulfides, metal phosphides, carbons, or their composites and their potential as electrode materials. In fact, MOF-derived materials exhibit exceptional conductivity, electrochemical activity, and stability, which surpass the relative low conductivity and lack chemical/structural robustness of pristine MOFs, inheriting only the essential structural and compositional properties from their MOF precursors.

Recent trends and perspectives in electrochemical sensors based on MOF-derived materials

Hollow nanostructured materials are suitable for electrochemical reactions because of their unique internal cavity and short transport path. Carbon-based nanomaterials, including simplex carbon materials, heteroatom-doped carbon materials, carbon-transition metal nanoparticle composites, and carbon-transition metal compound composites, are promising electrode materials because of their high conductivity and stable structure. Hollow carbon-based nanomaterials, which possess the features of the aforementioned materials, have become a research hotspot in electrochemical energy storage and electrocatalysis. The excellent characteristics of metal–organic frameworks (MOFs) make them an ideal material for constructing hollow carbon-based nanomaterials. In this article, the process of preparing MOF-derived hollow carbon-based materials and their applications in electrochemical energy storage and electrocatalysis are reviewed. First, the various methods for preparing MOF-derived hollow carbon-based materials are introduced, and the characteristics of each method are analyzed. Second, the applications of MOF-derived hollow carbon-based materials in the oxygen evolution reaction, oxygen reduction reaction, hydrogen evolution reaction, lithium-ion batteries, sodium-ion batteries, lithium–sulfur batteries, and supercapacitors are analyzed and summarized. Finally, research directions for further development of MOF-derived hollow carbon-based materials are proposed.

Ying Wei

Papers

Design of hollow carbon-based materials derived from metal–organic frameworks for electrocatalysis and electrochemical energy storage

Heat treatment-induced Co3+ enrichment in CoFePBA to enhance OER electrocatalytic performance