Collection of MOFs(202309)
Lithium-ion batteries (LIBs) are widely applied to various portable electronic devices and new energy vehicles. However, the traditional graphite anode with low theoretical capacity (372 mAh/g) is unable to meet the need of the rapid development of economy and society. Herein, a zinc-based metallic organic framework (ZIF-8) derived three-dimensional network carbon coated silicon (Si@NC) composite was designed for lithium-ion battery. Firstly, the surface of nano-silicon was chemical modified; secondly, small size ZIF-8 was in situ grown on the silicon surface to form Si@ZIF-8; finally, the three-dimensional network Si@NC composite was obtained by carbonization. Results show that the three-dimensional network porous structure of the Si@NC composite not only limits the volume expansion of silicon, but greatly improves the conductivity of the materials, exhibiting excellent cycle stability and outstanding rate performance. As a result, a discharge specific capacity of 760 mAh/g is maintained at a high current density of 5 A/g. Using commercial material as cathode and Si@NC as anode, the assembled full LIBs demonstrate a capacity retention of 60.4% at 0.4C (1C =160 mA/g) for 50 cycles. These results indicate that the as-synthesized three-dimensional network porous structure of Si@NC composite has a potential practical application for LIBs.
Room temperature ionic liquid shows wide electrochemical windows and good environmental stability, which is expected as an ideal electrolyte for electrochromic devices. However, the small crystal spacing of traditional electrochromic materials limits the diffusion of large ions in ionic liquid. Repeated deintercalation/ intercalation of large ions could also destroy the structure of traditional electrochromic materials, resulting in performance degradation. Metal-organic frameworks (MOFs) are topologically porous materials with a large intrinsic nano to microporous structure in crystalline, which are expected to provide channels for transporting large-sized ions in ionic liquids. In present work, triphenylene-based MOFs Cu3(HHTP)2 films were prepared on the surface of the conductive glass. Electrochemical and electrochromic behavior of Cu3(HHTP)2 films were studied in traditional propylene carbonate (PC)-based electrolyte and ionic liquid-based electrolytes. The results show that, compared with the traditional LiClO4/PC or NaClO4/PC electrolyte, Cu3(HHTP)2 film displays low contact resistance and high ion diffusion efficiency in the ionic liquid [EMIm]BF4 electrolyte. Switch speed of the electrochromic electrode is significantly improved with coloring time being reduced from 10.3 s to 8.0 s, and bleaching time being reduced from 23.6 s to 5.2 s. Meanwhile, Cu3(HHTP)2/[EMIm]BF4 electrochromic system also shows a larger light modulation range and coloring efficiency. This work demonstrates the potential of MOFs/ionic liquid electrochemical system in the field of electrochromic device.
Broad application of nuclear energy has resulted in the release of radionuclides such as uranium [U(VI)], into the environment, and its potential toxic and irreversible effects on the environment are among the paramount issues in nuclear energy use. Graphite carbon nitride (g-C3N4) is a kind of non-metallic material with the triazine structure. In recent years, the reduction of U(VI) to insoluble U(IV) by g-C3N4 photocatalysis has become a major research focus on the area of radioactive pollutants. In this work, a metal-organic framework (MOF) material containing cobalt metal was used as a self-sacrificial template. Through simple thermal copolymerization, the Co-Nx coordination was successfully incorporated into g-C3N4 to synthesize the CoNx/g-C3N4 photocatalyst. The effects of the morphology, structure, and photoelectric properties of CoNx/g-C3N4 on the photocatalytic reduction of U(VI) were investigated using macroscopic batch experiments. The results showed that the introduction of Co effectively broadened the absorption range of g-C3N4 to visible light, inhibited recombination of the photogenerated electrons and holes, and facilitated the reduction of U(VI). Under irradiation in visible light for 45 min, pH 5.0 and solid-liquid ratio of 1.0 g/L, the photocatalytic reduction of a standard 50 mg/L U(VI) solution reached 100% by CoNx/g-C3N4(w(Co-MOFs) : w(g-C3N4)=1 : 1). Furthermore, the photocatalytic mechanism of CoNx/g-C3N4 was investigated through capture experiments. In summary, the CoNx/g-C3N4 composite exhibits excellent optical performance, has simple operation, is eco-friendly, and has a significant photocatalytic effect on U(VI) in radioactive wastewater. This work also provides design strategy and technical reference for applying g-C3N4 materials to treat radioactive wastewater.
Luminescent materials have been widely used in confidential information protection and anticounterfeiting. Luminescent lead halide perovskite nanocrystals, which can be converted from the lead source through a two-step method, are attractive candidates for information encryption and decryption. Herein, the reversible conversion between the invisible lead-organic framework and the luminescent MAPbBr3 nanocrystals is achieved, together with their further application on information storage by inkjet printing technology. The lead ions are embedded into the metal-organic frameworks through coordination with the 2-methylimidazole linkers. The inherent confined distribution of lead ions facilitates the in-situ growth of perovskite nanocrystals in the second step without the assistance of external bulky ligands. The recorded information was firstly encrypted by the lead organic frameworks, which is invisible under ambient and UV light. After reacting with methylammonium bromide, the perovskite nanocrystals are in-situ formed, and the information becomes readable under UV light. Using methylammonium bromide and water as the decryption and encryption reagents could also switch on/off the luminescence, therefore, realizing the confidential information storage.
As a common air pollutant, nitrogen dioxide (NO2) gas does serious harm to the natural environment and human health. Therefore, it is imperative to develop efficient detection methods for detecting such toxic and harmful gases. Developing a new type of composite film gas sensor to achieve high selectivity and high sensitivity detection of nitrogen dioxide at room temperature has become a research hotspot. Here, we prepared zeolitic imidazolate framework 8 /reduced graphene oxide (ZIF8/rGO) composite with porosity and large specific surface area through chemical precipitation and ultrasonic method. Based on this materials, an NO2 sensor was constructed and then evaluated at room-temperature. Its possible mechanism of sensing NO2 was explored. The results showed that ZIF8/rGO sensor presented a response of 34.77% toward 50×10-6 NO2, which was 3.2-fold of pure rGO senor. Meanwhile it exhibited excellent repeatability after 4 reversible cycles with the relative standard deviation (RSD) only 3.9% and remarkable long-term stability in four-week test with the RSD of 2.5%, accompanied outstanding selectivity toward NO2 and a low limit of detection of 3.8×10-8. These hypersensitive properties at room temperature were attributed to its porous structure and large specific surface and high performance of rGO. This work offers a new idea for efficiently detecting poisonous NO2 based on ZIF8/rGO.
Metal-organic frameworks (MOFs) are widely used in biomedicine due to their porous structure, high specific surface area, abundant functional groups with metal active sites, good biocompatibility, and suitable degradability. In this study, a multifunctional composite nanoparticle (Fe(VI)@PCN@BSA) was prepared for combined photodynamic and chemodynamic therapy of tumors, which was constructed by loading potassium ferrate (K2FeO4, Fe(VI)) in porphyrin-based MOFs (PCN-224) and following a surface coating with biocompatible bovine serum albumin (BSA). The results showed that the particle sizes of PCN-224 and Fe(VI)@PCN@BSA nanoparticles were about 90 nm and 100 nm, respectively. Interestingly, Fe(VI)@PCN@BSA nanoparticles could catalyze H2O2 to produce •OH under a simulating tumor environmental condition. Meanwhile, they catalyzed to decompose H2O2 to produce O2, and thereby increased the production of singlet oxygen (1O2) under 660 nm laser irradiation, which enhanced the photodynamic effect. More importantly, in vitro evaluation indicated that Fe(VI)@PCN@BSA nanoparticles were biocompatible, and exhibited enhanced photodynamic and chemodynamic combined therapeutic efficacy against tumor cells. Hence, Fe(VI)@PCN@BSA nanoparticles have a great potential application in tumor therapy.
Metal organic frameworks(MOFs) nanofibrous membranes (NFMs) based on electrospinning technology integrate the advantages of inorganic porous materials and polymer nanofibers, enabling them a class of functional materials with broad application prospects. MOFs NFMs with different functions are explored continuously and their application fields are expanding. In this work, we briefly introduce the development of MOFs NFMs, which has experienced a gradual transformation from preparation research to application research. Then, the main methods on preparing MOFs NFMs, including mixed electrospinning, in situ growth, multistep seeded growth, and atomic layer deposition, are described in detail. The main application and of current MOFs NFMs, such as adsorption and separation, heterogeneous catalysis, sensing detection are expounded. And, we put forward the future prospect of the development directions and trends of MOFs NFMs.
Solid polymer electrolytes (SPEs) with high flexibility and processability enable the fabrication of leak-free solid-state batteries with varied geometries. However, SPEs usually suffer from low ionic conductivity and poor stability with lithium metal anodes. Here, we propose nano-sized metal-organic framework (MOF) material(UiO-66) as filler for poly(ethylene oxide) (PEO) polymer electrolyte. The coordination of UiO-66 with oxygen in PEO chain and the interaction between UiO-66 and lithium salt significantly improve the ionic conductivity (3.0×10 -5 S/cm at 25 ℃, 5.8×10 -4 S/cm at 60 ℃) and transference number of Li + (0.36), widen the electrochemical window to 4.9 V (vs Li +/Li), enhance the stability with lithium metal anode. As a result, the as-prepared Li symmetrical cells can continuously operate for 1000 h at 0.15 mA?cm -2, 60 ℃. The results show that UiO-66 filler is effective to improve the electrochemical performance of polymer electrolyte.