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1.
The modification of covalent organic frameworks (COFs) based on postsynthetic covalent linkages is discussed in this review. In this strategy, the COF is preparedas scaffold and then assembled with functional groups with preservation of structural skeleton. Recent studies indicate that a number of COFs, such as COF-5 and 3D-OH-COOF, are controllable to postsynthetic modification. Furthermore, covalentmodifications including triazole, ester, amide, sulfide, o-carbamate, ether, and oxime are suitable for postsynthetic functionalization. The rapid development of postsynthetic modification demonstrates that this approach will provide a general platform to create COFs as robust functional porous materials for wide applications. 相似文献
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Cai-Yue Wang Meng-Qi Gao Cheng-Cai Zhao Li-Min Zhao Hui Zhao 《Frontiers of Chemical Science and Engineering》2022,16(9):1367
The exploration of efficient bifunctional electrocatalysts for oxygen reduction reaction and oxygen evolution reaction is pivotal for the development of rechargeable metal–air batteries. Transition metal phosphides are emerging as promising catalyst candidates because of their superb activity and low cost. Herein, a novel metal phosphonate-derived cobalt/nickel phosphide@N-doped carbon hybrid was developed by a carbothermal reduction of cobalt/nickel phosphonate hybrids with different Co/Ni molar ratios. The metal phosphonate derivation method achieved an intimately coupled interaction between metal phosphides and a heteroatom-doped carbon substrate. The resultant Co2P/Ni3P@NC-0.2 enables an impressive electrocatalytic oxygen reduction reaction activity, comparable with those of state-of-the-art Pt/C catalysts in terms of onset potential (0.88 V), 4e‒ selectivity, methanol tolerance, and long-term durability. Moreover, remarkable oxygen evolution reaction activity was also observed in alkaline conditions. The high activity is ascribed to the N-doping, abundant accessible catalytic active sites, and the synergistic effect among the components. This work not only describes a high-efficiency electrocatalyst for both oxygen reduction reaction and oxygen evolution reaction, but also highlights the application of metal phosphonate hybrids in fabricating metal phosphides with tunable structures, which is of great significance in the energy conversion field. 相似文献
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设计了应用于全钒液流电池的尺寸筛分效应共价有机框架/聚醚砜(COF/PES)复合膜,利用纳米片的有序交错堆叠在聚醚砜支撑层上构建了具有均匀埃米级离子传输通道的连续COF分离层。连续COF层的规整刚性骨架赋予了膜极低的溶胀比,有序的埃米级孔道(有效孔径约为0.6 nm)对氢/钒离子具有精确的尺寸筛分作用。COF/PES筛分复合膜的钒渗透率仅有0.61×10-8 cm-2·s-1,质子/钒离子选择性为Nafion 212的4.0倍。电流密度为80 mA·cm-2下复合膜的能量效率达到82.9%,优于Nafion 212(81.2%)。100 mA·cm-2下的长循环测试中,复合膜电池容量保持率相比于Nafion 212电池提高了16.2%,表明连续COF/PES筛分复合膜在全钒液流电池中具有广阔的应用前景。 相似文献
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设计了应用于全钒液流电池的尺寸筛分效应共价有机框架/聚醚砜(COF/PES)复合膜,利用纳米片的有序交错堆叠在聚醚砜支撑层上构建了具有均匀埃米级离子传输通道的连续COF分离层。连续COF层的规整刚性骨架赋予了膜极低的溶胀比,有序的埃米级孔道(有效孔径约为0.6 nm)对氢/钒离子具有精确的尺寸筛分作用。COF/PES筛分复合膜的钒渗透率仅有0.61×10-8 cm-2·s-1,质子/钒离子选择性为Nafion 212的4.0倍。电流密度为80 mA·cm-2下复合膜的能量效率达到82.9%,优于Nafion 212(81.2%)。100 mA·cm-2下的长循环测试中,复合膜电池容量保持率相比于Nafion 212电池提高了16.2%,表明连续COF/PES筛分复合膜在全钒液流电池中具有广阔的应用前景。 相似文献
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The versatility of porphyrins as optoelectronic or catalytic units makes them attractive elements for inclusion in functional materials. Polymers that include porphyrins have been created with a wide variety of structures and used in a wide range of applications. This review covers recent developments in the synthesis, characterization and applications of polymeric materials in which porphyrins are key components of the repeat units, including the rapidly growing area of metal–organic frameworks and related covalent organic frameworks. © 2015 Society of Chemical Industry 相似文献
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Jun Chen Liandong Li Liu Yang Chang Chen Shitao Wang Yan Huang Dapeng Cao 《中国化学工程学报》2022,43(3):161-168
Developing high efficient bifunctional oxygen electrocatalysts for clean energy applications like Zin-air battery (ZAB) is highly desired, because it would reduce the cost and speed up the practical application of ZAB. Here we use a dual metal–organic framework (MOF) synthesis strategy to prepare the N-doped carbon supported bimetallic FeCo nanoparticle catalysts (marked as FeCo@NC) by pyrolysis of ZnCo-ZIF/MIL-101(Fe) composite. The FeCo@NC exhibits remarkable electrocatalytic activity for ORR with half-wave potential of 0.89 V vs. the reversible hydrogen electrode (RHE) and robust durability for both ORR and OER (oxygen reduction reaction and oxygen evolution reaction), which is attributed to the generation of Fe0.26Co0.74 crystalline phase and mesopores due to the dual-MOF synthesis strategy. The rechargeable ZAB based on FeCo@NC air electrode shows a maximum energy density of 139.6mW·cm-2 and excellent cyclic stability over 130 h, significantly surpassing the Pt and Ir-based ZAB. The present work provides a useful dual-MOF synthesis strategy for preparing high-performance multifunctional catalysts for ORR, OER and hydrogen evolution reaction (HER). 相似文献
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将柠檬酸铁铵作为Fe源掺入叶片状ZIF-L前驱体中,经过分段式高温热解成功制备出形貌维持良好的二维片状的Fe-NC催化剂。通过探究Fe载量对催化性质的影响发现,Fe-NC-1%催化剂在碱性电解质中呈现出最为优异的氧还原反应（ORR）活性,半波电位E1/2达到了0.897 V,动力学电流密度J0.85 V为26.70 mA/cm2,5 000次循环过后E1/2衰减5 mV,均超过了商业Pt/C催化剂。结合Raman光谱、XPS、BET法比表面积测定等分析表明,Fe-NC-1%的大比表面积、高石墨化程度、丰富的含氮活性物种等优势赋予了较高的传质效率及催化活性位点利用率,是促进其ORR反应动力学的重要因素。 相似文献
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利用溶剂热法合成了一种二维的共价有机框架（DMTP-TAPB COF）材料。通过X射线衍射仪（XRD）、扫描电子显微镜（SEM）和热重分析仪（TGA）对合成材料的结构、形貌和性能进行了详细的研究。然后研究了制备的共价有机框架材料对于靛蓝胭脂红染料（IC）的吸附能力,考察了不同吸附时间、不同p H和不同靛蓝胭脂红的初始浓度对吸附性能的影响。实验结果表明,制备的二维共价有机框架材料具有良好的结晶度和均匀的形貌。同时,DMTP-TAPB COF对靛蓝胭脂红具有较高的吸附能力（330.5 mg/g）和移除效率（84.5%）,吸附过程符合准二级动力学方程和Langmuir吸附模型。该研究表明共价有机框架材料作为污染物的吸附剂具有广阔的应用前景。 相似文献
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《Ceramics International》2022,48(5):6506-6511
Precious metal-free bifunctional electrocatalysts with efficient performance to ORR (oxygen reduction reaction) and OER (oxygen evolution reaction) are the prerequisite to the commercialization of rechargeable Zn-air battery (RZAB). Here, ultrathin amorphous MnO2 modified prawn shells-derived porous carbon (U–MnO2/PSNC) is designed and synthesized via a self-template assisted pyrolysis coupling in-situ redox reaction strategy. In this composite, the ultrathin amorphous MnO2 provides high surface defects and homogeneous catalytic active sites. The conductive prawn shells-derived porous carbon displays macro-meso-microporous structure, promoting electric conductivity and offering fast pathway for mass diffusion. With optimized composition, the U–MnO2-0.01/PSNC delivers an excellent bifunctional to ORR/OER with a small ΔE (bifunctional activity parameter) value of 0.776 V. Moreover, the RZAB equipped with U–MnO2-0.01/PSNC displays a considerable stability with narrow decay of battery efficiency (1.10%) for ～334 h (500 cycles) at 10 mA cm?2. This work enlightens a new pathway to design cost-effective bifunctional electrocatalysts for metal-air battery. 相似文献
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共价有机框架（COFs）是一种由C、B、N、O等轻元素通过强共价键有序连接形成的周期性网状结构的有机多孔材料,具有比表面积大、密度低、孔道规则、易修饰、结构多样、稳定性好等优点,在众多领域得到了广泛应用。本综述介绍了COFs的结构,总结了合成COFs的硼酸缩聚反应、C-C偶联反应、席夫碱反应、氰基自聚和芳醚聚合等反应类型的进展,并介绍了COFs的溶剂热合成法、微波加热合成法、离子热合成法、机械研磨合成法、界面合成法、微流控合成法及后合成修饰等制备方法,进而讨论了COFs结构的表征方法。此外,对COFs在气体吸附与分离、光催化、电催化、不对称催化合成及手性分离、电化学储能等领域的研究进展进行了总结。最后对目前COFs合成和应用的机遇和挑战进行了展望,希望能为COFs的进一步深入研究提供有益的启发和参考。 相似文献
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Hongyan Cao Yu Xia Yuqin Lu Yulin Wu Yongsheng Xia Xiaoxuan Hou Yixing Wang Gongping Liu Kang Huang Zhi Xu 《American Institute of Chemical Engineers》2022,68(6):e17657
Molecular sieving metal–organic framework (MOF) polycrystalline membranes have great potential for ion sieving and are desirable as efficient separators for devices of energy storage such as flow battery. Herein, we report a continuous MOF-801 polycrystalline membrane with an ultrathin polymeric assembly layer (less than 10 nm) for the vanadium flow battery (VFB). Owing to the precise sub-nanometer sieving pores and abundant H-bond networks in MOF-801 frameworks, the membrane exhibited better H/V selectivity (up to 194) and conductivity (about 0.028 S/cm) than commercial Nafion-117 membrane (H/V selectivity: ~9.5, conductivity: 0.017 S/cm). VFB results revealed that a cell with above MOF polycrystalline membrane showed high coulombic efficiency (CE: 96.1%) and excellent energy efficiency (EE: 83.2%) at 20 mA/cm2, which was much comparable to Nafion membrane. This work demonstrates that MOF polycrystalline membrane is a promising candidate as ion sieving membrane for energy technique. 相似文献
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Tatsuhiro Okada Satoshi Gotou Masaya Yoshida Makoto Yuasa Takuji Hirose Isao Sekine 《Journal of Inorganic and Organometallic Polymers》1999,9(4):199-219
Reduction of platinum catalysts loading is a central issue in polymer electrolyte fuel cells. As alternatives for platinum, some organic metal chelate compounds are tested as cathode catalysts, such as cobalt aza-complexes or cobalt complexes possessing aminophenyl moieties featured as Co-N4 or Co-N2O2 chelate structures. The way of immobilization of catalysts on the graphite surface influences their stability as well as the performance of oxygen reduction. Heat-treated catalysts supported on graphite at 600°C show much better oxygen reduction abilities than as-received metal complexes. The original chemical structure of metal complexes affects crucially the catalytic ability, though initial structures of molecules are no more intact after the heat treatment. The catalytic activity of these complexes may originate from the central chelate unit CoN4 on the carbon substrate, and this unit is assumed to constitute the basic coordination site for an oxygen molecule. Electropolymerized catalysts impart a high level of oxygen reduction ability, probably due to the improved molecular orientation for oxygen coordination and formation of good chelate sites on the graphite surface. 相似文献
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Hydrophilicity is key factor to sub-nanometer channels for water transport. However, how to effectively integrate the respective advantages of hydrophilicity and hydrophobicity to realize ultrafast water transport at the sub-nanometer scale is still confusing. By using sub-nanometer channels formed by two-dimensional covalent organic frameworks as typical models, we herein demonstrate that alternating hydrophilic–hydrophobic patterns in channels are capable of significantly improving water transport. Alternatingly stacking hydrophilic and hydrophobic monolayers is testified to be energetically favorable to directly piling their multilayers. Meanwhile, alternatingly-stacked hydrophilic–hydrophobic multilayers are able to achieve much higher water permeability than individual hydrophilic or hydrophobic multilayers. The effect of framework flexibility is also investigated. The exceptional performances benefit from the perfect balance between excellent wettability of hydrophilicity and low friction of hydrophobicity. In order to give full play to the synergistic advantages, the thickness of hydrophobic patterns spaced by hydrophilic ones should be less than 1 nm. 相似文献
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通过溶液合成法制备了一种共价有机框架（COF）,再将COF包覆在焦磷酸哌嗪（PAPP）上形成PAPP@COF杂化阻燃剂,并将其应用于EP中。通过氧指数测定仪、垂直燃烧测定仪和锥形量热仪分析了PAPP@COF杂化阻燃剂对EP的阻燃及消烟性能的影响。结果表明,加入2%（质量分数,下同）的PAPP@COF时,EP复合材料的氧指数达到了30.0%,热释放速率峰值为911.35 k W/m2,烟释放速率峰值为0.394 m2/s,相比于纯EP分别降低了37.36%和34.27%。PAPP@COF杂化阻燃剂对EP有优异的阻燃和消烟作用,为COF类阻燃剂的研究提供了一定的基础。 相似文献
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Revathi Purushothaman;C. K. Arvinda Pandian; 《Polymer Engineering and Science》2024,64(9):4539-4550
Polyimides are used in various applications, including fuel cells, membranes, and microelectronics, due to their outstanding tensile properties, great thermal stability, low dielectric constant, and chemical inertness. Applications requiring even lower dielectric constants include interlayer dielectrics and tape-automated bonding. In this study, a covalent organic framework (COF-1) was synthesized and dispersed in various percentages into a solution of terpoly(amide acid) (TPAA) to produce COF-1/terpolyimide composites. 3,3′,4,4′-Oxydiphthalic dianhydride (ODPA), 3,3′,4,4′-biphenyltetracarboxylicdianhydride (BPDA), and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) were reacted with 4,4′-(hexafluoroisopropylidene)bis[(4-aminophenoxy)benzene] (HFBAPP) or 4,4′-(hexafluoroisopropylidene) dianiline (6FpDA) to form terpoly(amide acid). In this case, monomers with fluorinated substituents (HFBAPP, 6FpDA, and 6FDA) were utilized to improve free volume. Pores of COF-1 and gaps between polyimide chains and COF-1 can be filled with air with a dielectric constant (κ) ~1, lowering the κ value of terpolyimide composites. The κ value of COF-1/terpolyimide composites decreased as COF-1 content increased, reaching a minimum of 1.96. Tensile properties decreased slightly with increasing COF-1 levels. The terpolyimides and their composites were thermally stable up to approximately 520°C. As a result, these polymer composites look promising for use as insulators in microelectronic applications. 相似文献
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In this study, a highly thermally stable benzimidazole based covalent organic framework (bCOF) was synthesized by the reaction of perlin‐tetracarboxylic anhydride, 5‐aminoisophthalic acid and diaminobenzidine in polyphosphoric acid medium. The synthesized porous bCOF was identified by different techniques. From CO2 adsorption, the micropore surface area of the bCOF was found to be 856 m2 g?1; this synthesized bCOF has a widespread netting construction, and it has various porosity. The TGA results displayed the high thermal strength of the synthesized bCOF. After characterization, the bCOF was used for the removal of methylene blue from aqueous solution, and the essential parameters such as pH of the solution, contact time and initial concentration were assessed. The maximum adsorption capacity of the bCOF for removal of methylene blue was 63.29 mg g?1 after only 40 min contact time at a pH of 6. Two kinetics and adsorption models were used for interpretation, and the outcomes showed that the pseudo‐second‐order and Langmuir models respectively were better fitted to the results. According to the results, the novel bCOF can be applied to remove methylene blue from aqueous solution. © 2020 Society of Chemical Industry 相似文献
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《Ceramics International》2021,47(21):30091-30098
Rational design and fabrication of optimal reversible oxygen electrocatalysts are essential yet still remain great challenges for rechargeable metal-air batteries. Supramolecular coordination polymer-derived strategy for transition metal–nitrogen–doped carbon (M–N/C, M = Co, Fe, etc.) composites catalysts has been deemed promising in preserving rich M–Nx coordination modes and enhancing their intrinsic activities. However, the closely packed and nonporous characteristics of coordination polymer usually lead to the serious agglomeration of metallic nanoparticles and lack of porous channels after pyrolysis, impacting the abundance and accessibility of the exposed active sites during electrocatalysis. In this work, we put forward a new tactic to obtain ultra-small Co nanoparticles confined within N-doped carbon nanotubes grafted to reduced graphene oxide (Co/N-CNTs@rGO) through a coordination-driven in situ self-assembly approach followed by pyrolysis. The integration of high intrinsic activity, enhanced conductivity, populated and richly exposed active species throughout the laminated hierarchical composite structure endows Co/N-CNTs@rGO with appealing bifunctional oxygen electrocatalysis properties. Impressively, Co/N-CNTs@rGO was subsequently fabricated as the air electrode in a rechargeable Zn−air battery, and the device achieves a maximum power density of 168 mW cm−2, a large specific capacity of 765 mA h g−1 while maintaining satisfying cycling durability. This work may provide valuable insights in regulating the coordination polymer derivatives and bring new perspectives for future design of promising composites electrocatalysts for electrochemical conversions and energy storage technologies. 相似文献