Imparting Functionality to Metal-Organic Frameworks for Potential Applications

Department of Chemistryope

Tetrazole-Based Energetic Metal-Organic Frameworks: Impacts of Metals and Ligands on Explosive Properties

New energetic materials are required to compensate for the shortcomings of the current ones. Especially secondary explosives are the ones with low-sensitivity, while maintaining energetic performance similar to those of primary ones, and particularly useful when safety must be ensured. Herein, we report two energetic metal-organic frameworks (eMOFs), eMOF-1, [Mn-5(mtz)(6.1)(atz)(2.9)(NO3)] (mtz=5-methyltetrazole, atz=5-aminotetrazole) and eMOF-2, [Cu(mtz)(2)], both of which have unique detonation and sensitivity properties. In particular, eMOF-1, firstly reported here, shows better energetic performance when compared with the previously reported material, Cd-based mtz MOF, an isostructural series. In addition, eMOF-2 synthesized in water shows a great detonation performance, whereas isotopological Zn-based mtz MOF did not show a meaningful performance as an explosive. Therefore, such reticular approach, i. e. replacing metal ions or ligands in isostructural frameworks, can be quite effective for the development of a new breed of energetic materials

All-impurities Scavenging, Safe Separators with Functional Metal-Organic-Frameworks for High-Energy-Density Li-Ion Battery

Li-ion batteries (LIBs) have wide applications owing to their high-energy density and stable cycle characteristics. Nevertheless, with the rapid expansion of electric vehicle market, issues such as explosion of LIBs and the need to secure a longer driving distance have emerged. In this work, functional metal-organic frameworks (MOFs) are introduced as a separator in LIBs, in which a highly heat-resistant polymer separator is fabricated through electrospinning. The MOFs can scavenge impurities (including gas, water, and hydrofluoric acid) that positively affect battery performance and safety. The multi-functional separator suppresses salt decomposition when a nickel-rich cathode is operated at high voltage and high temperature through it. This delays the deterioration of the cathode interface and results in a superb cycle stability with 75% retention even in the presence of 500 ppm of water in the electrolytes. In addition, the pouch cell is manufactured by enlarging the separator, and the degree of electrode swelling due to gas generation and interface degradation in the pouch state is alleviated to 50% or less. These findings highlight the necessity of scavenging impurities to maintain excellent performance and provides the development direction of functional separators in LIBs

Interface-Sensitized Chemiresistor: Integrated Conductive and Porous Metal-Organic Frameworks

Research to develop ideal sensing devices for toxic gases is on the rise, and amongst various materials, metal--organic frameworks (MOFs) have opened up promising vistas as chemiresistive sensors due to their high structural and functional tunability. Here, we report the composites of dimensionally (2D and 3D) and func-tionally (conductive and porous) different two MOFs in the form of a well-integrated core-shell structure. The hierarchically assembled 2D-MOF@3D-MOF exhibits new interfacial properties that are responsible for syn-ergetically enhanced sensing performances toward toxic H2S gas with the lowest recorded limit of detection (1.4 ppb), superior sensitivity (& UDelta;R/R0 = 3.37), and outstanding selectivity at room temperature in air. The sensing mechanisms are proposed by combinational studies of experiments and calculation, which indicates that multiple changes (e.g., local structural change of the shell MOF, secondary binding sites generation from the core MOF, and free radicals formation) play a critical role in achieving synergetic chemiresistive sensing