Facile fabrication of MOF-decorated nickel iron foam for highly efficient oxygen evolution

Metal-organic frameworks (MOFs) have emerged as efficient electrocatalysts due to the features of high specific surface area, rich pore structure and diversified composition. It is still challenging to synthesize self-supporting MOF-based catalysts using simple and low-cost fabrication methods. Herein, we successfully fabricated Ni-doped MIL-53(Fe) supported on nickel-iron foam (Ni-MIL-53(Fe)/NFF) as efficient electrocatalyst. A facile two-step solvothermal method without adding any metal salts was used, which can simplify the fabrication process and reduce the experimental cost. In the fabrication process, the bimetallic Ni-MIL-53(Fe)/NFF was in situ converted from an intermediate NiFe₂O₄/NFF. The obtained material exhibits outstanding electrocatalytic oxygen evolution performance with a low overpotential of 248 mV at 50 mA cm^?2, and a small Tafel slope of 46.4 mV dec^?1. This work sheds light on the simple and efficient preparation of bimetallic MOF-based material, which is promising in electrocatalysts.     

Synthesis of hollow Fe,Co, and N-doped carbon catalysts from conducting polymer-metal-organic-frameworks core-shell particles for their application in an oxygen reduction reaction

Oxygen reduction reaction (ORR), one of the key reactions for fuel cells and zinc-air batteries, should be improved for higher performance. Herein, we fabricated hollow Fe, Co, and nitrogen co-doped carbon (H-FeCo-NC) catalyst, which was prepared by carbonization of core-shell particles made of polypyrrole (PPy)-coated polystyrene (PS) spheres as cores and (Zn, Co) bimetallic-zeolitic imidazolate frameworks (ZnCoBZIFs) as shells. PPy was used as a nitrogen and a carbon source. The H-FeCo-NC catalyst had a high surface area of 324.08 m² g^?1 with uniformly distributed Fe and Co species, and excellent ORR performance with the half-wave potential of 0.888 V vs. reversible hydrogen electrode in alkaline media. Furthermore, the H-FeCo-NC catalyst demonstrated exceptional stability, durability, and tolerance to methanol crossover.     

Micromembrane absorber with deep-permeation nanostructure assembled by flowing synthesis

A micromembrane adsorber with deep-permeation nanostructure (DPNS) has been successfully fabricated by flowing synthesis. The nanoparticles are in-situ assembled in membrane pores and immobilized in each membrane pore along the direction of membrane thickness. The nanoparticles with a lower size and thinner size distribution can be achieved owing to the confined space effect of the membrane pores. As a concept-of-proof, the nano ZIF-8 and ZIF-67 are fabricated in porous membrane pores for methyl orange (MO) and rhodamine B (RhB) adsorption. The adsorption rate is increased significantly owing to the enhanced contact and mass transfer in the confined space. The adsorption capacity for the RhB is also increased, since the size of the nanoparticles assembled in membrane pores is smaller with more active sites exposed. This micromembrane adsorber with DPNS has good reusability and can provide a promising prospect for industrial application.     

红色烟火着色剂MOF[Sr2(DTDA)(H2O)6]n的制备与性能

以富氮羧酸类分子2,2'-(3,3'-偶氮-双(1H-1,2,4-三唑-5基))二乙酸(H2DTDA)与氢氧化锶八水合物为原料,在水热条件下制备了一种金属有机框架(MOF)结构的新型红色烟火着色剂[Sr_2(DTDA)(H_2O)_6]_n(1);采用傅里叶变换红外光谱(FT-IR)、X射线单晶衍射(XRD)、粉末X射线单晶衍射(PXRD)和元素分析等对化合物结构进行了表征;采用热重法(TG)-差示扫描量热法(DSC)、BAM标准法测试了化合物1的热性能和感度性能;设计了烟火剂配方,对化合物1应用于红色烟火着色剂的可行性进行分析。结果表明,化合物1是一种具有二维空间结构的MOF材料,其层状结构之间存在丰富的氢键作用;放大合成的水热实验同样可以得到高纯度的化合物1;撞击感度为80 J,摩擦感度 360 N;化合物1可作为红色着色剂应用于烟火剂配方中。     

金属有机骨架材料（MOFs）用于气态轻烃的高效分离研究进展

气态轻烃（C₁～C₃）如甲烷、乙烯、丙烯分别作为应用最广的清洁燃料和大宗化工产品，在国民经济中占据重要的地位。然而，在其生产过程中广泛存在着分离与提纯能耗较高的问题。金属有机骨架材料（MOFs）作为第三代新型多孔材料，近年来在轻烃分离领域显示出巨大的应用潜力。本文综述了MOFs用于气态轻烃分离的现状和机理，总结了本文作者课题组针对不同轻烃产物的分离要求，对MOFs进行了精确的孔径调控、配体功能化修饰、构筑吸附位点、调变柔性结构“开口压力”等，实现了多种气态轻烃组分的高效分离。最后，针对低碳烃工业分离过程中存在的关键问题，对MOFs材料的吸附分离机理进行了深入分析，以及MOFs工业化应用所面临的结构稳定性与分离工艺匹配等进行了展望。     

共价有机框架材料及其在关键核素分离中的应用进展

共价有机框架材料（COFs）是一类由共价键连接的多孔晶态材料。因具有单体链接方式灵活、结构可调、活性位点丰富、比表面积大、理化性质相对稳定等特点，它们在气体储存与分离、能量储存、催化和光电学领域受到了广泛的关注。本文主要从结构设计、合成方法及功能化、材料的分析表征和晶形控制等方面概括地介绍了COFs材料。在此基础上，综述了COFs材料在关键核素分离方面的研究进展，并展望了其在核素分离领域的应用前景和今后的研究方向。     

Flexible,Mechanically Stable,Porous Self-Standing Microfiber Network Membranes of Covalent Organic Frameworks: Preparation Method and Characterization

Covalent organic frameworks (COFs) show advantageous characteristics, such as an ordered pore structure and a large surface area for gas storage and separation, energy storage, catalysis, and molecular separation. However, COFs usually exist as difficult-to-process powders, and preparing continuous, robust, flexible, foldable, and rollable COF membranes is still a challenge. Herein, such COF membranes with fiber morphology for the first time prepared via a newly introduced template-assisted framework process are reported. This method uses electrospun porous polymer membranes as a sacrificial large dimension template for making self-standing COF membranes. The porous COF fiber membranes, besides having high crystallinity, also show a large surface area (1153 m² g⁻¹), good mechanical stability, excellent thermal stability, and flexibility. This study opens up the possibility of preparation of large dimension COF membranes and their derivatives in a simple way and hence shows promise in technical applications in separation, catalysis, and energy in the future.     

MOF衍生的高选择性加氢芳香硝基化合物的石墨碳包覆镍催化剂

针对芳香硝基化合物的催化选择性加氢反应，开发可替代贵金属催化剂的低成本、高效非贵金属催化剂，对于芳香胺类化合物的绿色生产具有重要意义。利用简易、可规模化的制备方法，以镍—2,5-吡啶二羧酸金属有机框架为前驱体，热解制备了氮掺杂石墨碳包覆镍纳米催化材料（Ni@CN）。采用X射线衍射、扫描电镜、透射电镜、元素分析、N2吸脱附等检测手段对Ni@CN的物化性质进行了表征，并对其催化性能进行了评价。结果表明，Ni@CN可在温和条件下（85℃，1.0 MPa H2)高效加氢含取代官能团的芳香硝基化合物生成对应的芳香胺类化合物。对比试验表明，镍纳米颗粒是Ni@CN的加氢活性中心，而石墨碳壳的存在有利于优先吸附硝基官能团。此外，进一步考察了Ni@CN的循环使用性能以及抗硫化物中毒的特性。     

Impact of defects on the decomposition of chemical warfare agent simulants in Zr-based metal organic frameworks

Metal organic frameworks (MOFs) containing zirconium secondary building units (SBUs) in UiO-67 and related MOFs, are highly active for neutralizing both the chemical warfare agents and simulants, such as dimethyl methylphosphonate (DMMP). However, two recent publications gave conflicting reports of DMMP reaction with UiO-67 under ultra high vacuum (UHV) conditions, with one reporting chemisorption and reaction (Wang et al., J Phys Chem C, 2017, 121, 11261–11272) and the other reporting only physisorption and reversible desorption (Ruffley et al., J Phys Chem C, 2019, 123, 19748–19758) from very similar temperature programmed desorption experiments. We show that the discrepancy between these experiments may be explained by different levels of missing linker defects in the UiO-67 samples. We present density functional theory calculations showing that SBU sites having two-adjacent missing linkers exhibit reaction barriers that are about 30 kJ/mol lower than SBU sites having a single missing linker. We also show that topology of the undercoordinated sites plays an important role in the reaction barrier under UHV conditions.     

A fast procedure for the estimation of the hydrogen storage capacity by cryoadsorption of metal-organic framework materials from their available porous properties

In order to identify the best porous materials for the cryogenic physisorption of hydrogen, high-throughput calculations are performed starting, i.e., from the collected information in crystallographic databases. However, these calculations, like molecular simulations, require specific training and significant computational cost. Herein, a relatively simple procedure is proposed to estimate and compare hydrogen uptakes at 77 K and pressure values from 40 bar starting from the porous properties of MOF materials, without involving simulation tools. This procedure uses definitions for adsorption and considers the adsorbed phase as an incompressible fluid whose pressure-density change is that for the liquid phase at 19 K. For the 7000 structures from the CoRE MOF database, the average error of the predictions is only of 1% from reference values at 100 bar, with an SD of ±8%. This accuracy is lower than that from simulation tools, but involving lower computational cost and training.