One-pot construction of highly oriented Co-MOF nanoneedle arrays on Co foam for high-performance supercapacitor

MOF-derived scaffolds as electrode materials: a mini-review

Metal-organic frameworks (MOFs) have unique properties but suffer from low conductivity and poor stability, limiting their use in energy storage. Transforming MOFs into other materials, like porous carbon or metal oxides/chalcogenides has been explored to overcome these limitations. However, these approaches still face issues such as dead volume and poor attachment due to insulating binders, causing high resistance and detachment. To address this, MOFs and their derived scaffolds directly on conductive substrates without binders have emerged. These electrodes offer simplified preparation, enhanced electron transfer, and improved interface contact. This mini-review focuses on MOF-derived scaffold electrodes using transition metal oxides, sulfides, selenides, and tellurides, which show promise in energy storage applications. Valuable insights, identified opportunities, and future suggestions in the field of MOF-derived scaffold electrodes and their applications in energy storage applications have been discussed.

Effect of synthesis temperature on the structural morphology of a metal-organic framework and the capacitor performance of derived cobalt-nickel layered double hydroxides

Three-dimensional interconnected nickel-cobalt layered double hydroxides (NiCo-LDHs) were prepared on nickel foam by ion exchange using a cobalt-based metal-organic framework (Co-MOF) as a template at different temperatures. The effects of the Co-MOF preparation temperature on the growth, mass, morphology, and electrochemical properties of the Co-MOF and derived NiCo-LDH samples were studied. The synthesis temperature from 30 to 50 °C gradually increased the mass of the active material and the thickness of the Co-MOF sheets grown on the nickel foam. The higher the temperature is, the larger the proportion of Co3+. β-Cobalt hydroxide (β-Co(OH)2) sheets were generated above 60 °C. The morphology and mass loading pattern of the derived flocculent layer clusters of NiCo-LDH were inherited from metal-organic frameworks (MOFs). The areal capacitance of NiCo-LDH shows an inverted U-shaped curve trend with increasing temperature. The electrode material synthesized at 50 °C had a tremendous specific capacitance of 7631 mF·cm-2 at a current density of 2 mA·cm-2. The asymmetric supercapacitor assembled with the sample and active carbon (AC) achieved an energy density of 55.0 Wh·kg-1 at a power density of 800.0 W·kg-1, demonstrating the great potential of the NiCo-LDH material for energy storage. This work presents a new strategy for designing and fabricating advanced green supercapacitor materials with large power and energy densities.

High-performance electrode of ZIF-67 metal-organic framework (MOF) loaded laser-induced graphene (LIG) composite for all-solid-state supercapacitor

This work demonstrates a facile and efficient methodology to synthesize a composite material of zeolitic imidazolate frameworks (ZIFs) and laser-induced graphene (LIG). This ZIF-67 loaded LIG composite (ZIF-67/LIG) has been adequately characterized for its morphology and structure, and its electrochemical performance has been specifically examined. As supercapacitors (SCs) electrode material, the ZIF-67/LIG composite exhibits superb electrochemical performance, owing to the inherent high porosity, abundant active sites, large specific surface area of ZIF-67, and the excellent conductive three-dimensional hierarchical porous network structure provided by LIG. In three-electrode system, ZIF-67/LIG composite electrode displays outstanding areal specific capacitance (C_A) of 135.6 mF cm^-2at a current density of 1 mA cm^-2with 1 M Na₂SO₄aqueous electrolyte, which is far greater than that of pristine LIG (7.7 mF cm^-2). Furthermore, the ZIF-67/LIG composite has been fabricated into an all-solid-state planar micro-supercapacitor (MSC). This ZIF-67/LIG MSC exhibits an impressiveC_Aof 38.1 mF cm^-2at a current density of 0.20 mA cm^-2, a good cycling stability of 80.3% capacitance retention after 3000 cycles, and a high energy density of 5.29μWh cm^-2at a power density of 0.1 mW cm^-2. All electrochemical results clearly manifest that as-prepared ZIF-67/LIG composite can be a candidate in energy storage field with exciting possibilities.

Unlocking active metal site of Ti-MOF for boosted heterogeneous catalysis via a facile coordinative reconstruction

Constructing sophisticated hollow structure and exposing more metal sites in metal-organic frameworks (MOFs) can not only enhance their catalytic performance but also endow them with new functions. Herein, we present a facile coordinative reconstruction strategy to transform Ti-MOF polyhedron into nanosheet-assembled hollow structure with a large amount of exposed metal sites. Importantly, the reconstruction process relies on the esterification reaction between the organic solvent, i.e. ethanol and the carboxylic acid ligand, allowing the conversion of MOF without the addition of any other modulators and/or surfactants. Moreover, the surface and internal structure of the reconstructed MOF can be well tuned via altering the conversion time. Impressively, the reconstructed MOF exhibits ∼5.1-fold rate constant compared to the pristine one in an important desulfurization reaction for clean fuels production, i.e. the oxidation of dibenzothiophene.