Calcination Of Metal-organic Framework Research Articles

Self-assembled flower-like carbon nanosheets for magnetic solid-phase extraction of microcystins from aquatic organism

Adsorbents with good dispersibility and high efficiency are crucial for magnetic solid-phase extraction (MSPE). In this study, flower-like magnetic nanomaterials (F-Ni@NiO@ZnO2-C) were successfully prepared by calcination of metal-organic framework (MOF) precursors that was stacked by two-dimensional (2D) nanosheet. The synthesized F-Ni@NiO@ZnO2-C has a flower-like layered structure with a large amount of pore space, promoting the rapid diffusion of targets. In addition, Zn2+ doped in MOF precursors was still retained that further produced strong metal chelation with targets. The unique structure of F-Ni@NiO@ZnO2-C was used as MSPE adsorbent, and combined with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) for extraction of three microcystins (MCs) detection, including microcystin-LR (MC-LR), microcystin-RR (MC-RR), microcystin-YR (MC-YR). The resulting method has a detection limit of 0.2–1.0 pg mL−1, a linear dynamic range of 0.6–500.0 pg mL−1 and has good linearity (R ≥ 0.9996). Finally, the established method was applied to the highly selective enrichment of MCs in biological samples, successfully detecting trace amounts of MCs (8.4–15.0 pg mL−1) with satisfactory recovery rates (83.7–103.1 %). The results indicated that flower-like magnetic F-Ni@NiO@ZnO2-C was a promising adsorbent, providing great potential for the determination of trace amounts of MCs in biological samples.

Strategy for the Preparation of ZnS/ZnO Composites Derived from Metal-Organic Frameworks toward Lithium Storage.

The synergistic effect between multicomponent electrode materials often makes them have better lithium storage performance than single-component electrode materials. Therefore, to enhance surface reaction kinetics and encourage electron transfer, using multicomponent anode materials is a useful tactic for achieving high lithium-ion battery performance. In this article, ZnS/ZnO composites were synthesized by solvothermal sulfidation and calcination, with the utilization of metal-organic frameworks acting as sacrificial templates. From the point of material design, both ZnS and ZnO have high theoretical specific capacities, and the synergistic effect of ZnS and ZnO can promote charge transport. From the perspective of electrode engineering, the loose porous carbon skeleton that results from the calcination of metal-organic frameworks can enhance composite material conductivity as well as full electrolyte penetration and the area of contact between the electrolyte and active material, all of which are beneficial to enhancing lithium storage performance. As expected, ZnS/ZnO anode materials displayed remarkably high specific capacities and outstanding performance at different rates. Combining material design and electrode engineering, this paper provides another idea for preparing anode materials with excellent lithium storage properties.

Alkali metal and alkali earth metal-modified La-Fe-based perovskite catalyzed coke combustion

Coke catalytic gasification is an efficient method of burning coke. The core of this technology is the preparation of efficient and stable catalysts. A series of different type La-Fe-based perovskite catalysts, including ABO3 (La1-xSrxFeO3, LaK0.04Sr0.25FeO3), R-P (LaK1.7Sr0.2Fe1.7O6) and A2B2O6 (LaKSr0.17Fe1.5O6, LaKSr0.2Fe1.8O6) were prepared by sol-gel method and calcination of metal-organic framework (MOF) precursor method. The activity of perovskite catalytic coke was tested by thermogravimetric analysis and tubular reactor. Among them, LaKSr0.17Fe1.5O6−MOF has the best catalytic activity, with T10, T50, and T90 values of 610.65 °C, 666.86 °C, and 705.84 °C, respectively. LaKSr0.17Fe1.5O6−MOF not only improves coke conversion but also reduces reaction temperature. DFT and experimental results show that doped K and Sr metals promote the formation of many active sites (oxygen vacancies) on the surface of LaKSr0.17Fe1.5O6−MOF, which reduces the adsorption energy of O2 molecules, realizes the oxygen exchange kinetics. The oxygen release regeneration process is achieved between perovskite lattice oxygen and O2 molecules. These processes synergistically promote coke conversion. In addition, it also has strong stable regeneration performance. These results provide a promising strategy for designing and preparing efficient and low-cost catalysts for the practical application of coke removal.

Hierarchical hollow CuO/Cu2O and Cu2O/Cu/C derived from metal–organic framework for non-enzymatic oxidation toward glucose

Constructing copper-based oxide composite with ingenious architecture is attracting enormous attention due to the synergistic effect of components and enhanced performance resulted from structure. Herein, hierarchical hollow CuO/Cu2O and Cu2O/Cu/C are prepared via calcining hierarchical tubular metal–organic framework (MOF) in air atmosphere and Ar atmosphere, respectively. With calcining in air atmosphere, the obtained hierarchical hollow CuO/Cu2O is constructed by nanosheets which is composed of particles in diameter of 20–30 nm. In Ar atmosphere, the synthesized hierarchical hollow Cu2O/Cu/C is constructed by larger particles in diameter of about 65 nm. And these differences in component and building unit are ascribed to different dominant reaction involved in calcination of MOF at different atmospheres. Notably, the hollow structure of parent MOF is perfectly remained, which contributes to the enhancement of copper-based oxide composites in electrocatalytic oxidation toward glucose. The hierarchical hollow CuO/Cu2O and Cu2O/Cu/C can be applied as an excellent glucose sensor with higher sensitivity, wider detection range and lower limitation of detection. Selecting suitable MOF as sacrificed template being calcined in effective atmosphere, provides a facile strategy for constructing derivant with functional structures and increased properties.

Complete catalytic oxidation of formaldehyde at room temperature on MnxCo3-xO4 catalysts derived from metal-organic frameworks

Developing cost-effective non-noble catalysts for completely decomposing formaldehyde (HCHO) into harmless CO2 and H2O at room temperature remains great challenges for indoor air purification. Herein, MnxCo3-xO4 solid solutions are prepared via the calcination of metal-organic frameworks (MOFs) with different Co/Mn molar ratios. The catalyst (Mn1Co1) achieves 100 % HCHO removal at room temperature for the first time, and possesses excellent stability. During an intermittent test and a non-stop 34 -h test, the HCHO removal efficiency remains almost 100 %. The complete oxidation of HCHO is confirmed by the disappearance of HCHO peaks and the increase of CO2 peak intensity in effluent gas analysis. In situ DRIFTS results show that formate species is the main intermediate and it can be further oxidized to CO2 and H2O as final products in the presence of water vapor. The superior catalytic activity and stability of the Mn1Co1 catalyst endow its great potential in the HCHO removal application.

Novel CoNi-metal-organic framework crystal-derived CoNi@C: synthesis and effective cascade catalysis.

Evaluating the catalytic influence of metal sites on derivates obtained from the calcination of metal-organic frameworks (MOFs) is very important for the rational construction of novel MOFs. Based on this catalytic functional guidance, two new Co-MOF and CoNi-MOF crystals were designed and synthesized, and further pyrolyzed to obtain corresponding porous carbon-based catalysts. Interestingly, the derivates exhibited better catalytic performance toward the tandem reaction of dehydrogenation of NH3BH3 and subsequent hydrogenation reduction of nitro/olefin compounds than those of the CoNi-ZIF (a star MOF)-derived CoNi@carbon and most metal catalysts. Significantly, the CoNi@C maintained excellent activity, even after 30 cycles, demonstrating its great longevity and durability, which are especially important for the practical application of metal catalysts in industrial catalysis.

Flower-like MOF-derived Co–N-doped carbon composite with remarkable activity and durability for electrochemical hydrogen evolution reaction

Electrochemical hydrogen evolution reaction (HER) is one of the most economical, sustainable, and attractive methods to produce hydrogen. Contemporarily, it is still a challenge to develop low-cost catalysts with high activity and durability for HER. Herein, we report a simple strategy to develop a Co–N-doped carbon electrocatalyst derived from a new cobalt metal-organic framework (MOF). The new flower-like 2D→3D MOF {[Co(BIPA)(5-OH-bdc)](DMF)}n (1) was constructed based on bis(4-(1H-imidazol-1-yl)phenyl)amine (BIPA) and 5-hydroxyisophthalic acid (5-OH-H2bdc). After that, the Co–N-doped carbon composite Co-MOF-800 was prepared via calcination of MOF 1. Interestingly, Co-MOF-800 exhibited excellent electrocatalytic activity and durability for HER. The onset potential (0.12 V) and Ej=10 value (0.193 V) of the Co-MOF-800 electrode were comparable to that of the most active non-precious metal HER electrocatalysts derived from other MOFs. The HER performance of Co-MOF-800 was stable without degradation even after long-term cycling.

ZIF-67 derived cobalt-based nanomaterials for electrocatalysis and nonenzymatic detection of glucose: Difference between the calcination atmosphere of nitrogen and air

Calcination of metal-organic frameworks (MOFs) with designed condition is an efficient and flexible method to synthesize electrocatalysts with high activity toward various applications. In this work, we propose a facile calcination procedure under N2 atmosphere utilizing zeolitic imidazolate framework-67 (ZIF-67) as the precursor to obtain cobalt nanoparticles-porous carbon composites (denoted as ZIF-N2) for nonenzymatic glucose detection in alkaline media. At the same time, calcination of ZIF-67 under air atmosphere with the same temperature was also carried out. The resulting product (denoted as ZIF-Air) was used as a comparison when evaluating the electrochemical performance of ZIF-N2. By means of a series of physicochemical and electrochemical characterizations, different calcination atmosphere show great effect on the properties of the resulting materials. ZIF-N2 shows the specific morphology with Co nanoparticles loaded on the porous carbon matrix, with superior conductivity, mass activity, and electrochemical effective surface area to ZIF-Air. Based on these distinct parameters, nearly 10 times higher response of ZIF-N2 is obtained toward glucose than that of ZIF-Air. The sensitivity of ZIF-N2 is calculated to be 0.227mA mM−1cm−2 in the linear range of 0.1–1.1mM, with LOD of 5.69μM. Finally, the nonenzymatic glucose sensing performance of ZIF-N2 modified screen-printed carbon electrode including selectivity, long-term stability and reproducibility were also proved to be outstanding. This work demonstrates the calcination of MOFs under designed condition can be a promising method to obtain electrocatalysts for electrochemical sensing application.