Solvent-free route for metal–organic framework membranes growth aiming for efficient gas separation

Industrial applications of membranes based on metal–organic frameworks (MOFs) are challenged by their complex fabrication procedures and poor processability, despite their huge potential for efficient gas separation. Especially, the consumption of a large amount of toxic, expensive solvent, and harsh operation by conventional solvothermal growth also make it less attractive for industrial production. Herein, a solvent-free method is proposed to fabricate continuous defect-free MOF membranes on commercial porous stainless steel substrates, where the metal precursors are electrodeposited on the support followed by a heat treatment with the ligand powder via solid-state reaction without using any solvent. This strategy is proven to be applicable for various MOF membranes and it is expected to be a facile, cheap, and environmental friendly way for future large-scale production. © 2018 American Institute of Chemical Engineers AIChE J, 65: 712–722, 2019     

Integration of MnO2 and ZIF-Derived nanoporous carbon on nickel foam as an electrode for high-performance supercapacitors

MnO₂ has the highest potential as a supercapacitor electrode; however, its disadvantage in electronic conductivity hinders its widespread use. This study reports the excellent electrochemical performance of MnMC/NF (MnO₂ and ZIF-derived nanoporous carbon on nickel foam) composites. MnMC/NF composites are produced when leaf-like Co-ZIF is annealed on nickel foam, followed by potassium permanganate treatment. When the annealing temperature reaches 700 °C, the maximum specific capacitance of 531 F/g is achieved at 1 A/g (456 F/g at 20 A/g) with a rate capability of 85.5%. MnMC/NF700 has a long cyclic stability, and the capacitance retention was 82% after 5000 cycles. The energy density of an assembled device using MnMC/NF700 composite as positive electrodes can reach 38.8 Wh/kg. This is due to the combined effect of nickel substrate's 3D porous structure and the excellent electronic conductivity of ZIF-derived nanoporous carbon. The unique configuration of MnMC/NF composites may provide a referable design for energy storage systems, including materials that have the highest potential for use as supercapacitor electrodes.     

亲疏水性CuBTC/PVDF复合膜应用于膜蒸馏抗油实验

采用水热法合成亲水性的CuBTC金属有机骨架(MOFs)颗粒，采用聚乙烯醇(PVA)作为黏合剂，用抽滤的方法将CuBTC颗粒附载在聚偏氟乙烯(PVDF)膜上，之后用戊二醛(GA)对PVA进行交联，制备出表层亲水、底层疏水的CuBTC/PVDF复合膜。通过场发射电子显微镜、比表面积及孔径分析仪、接触角测量仪、孔径分析仪、X射线衍射仪等对CuBTC颗粒和不同CuBTC含量的复合膜的表面特征、结构形态和稳定性进行了表征。结果表明，CuBTC颗粒有着较大的比表面积和孔容，CuBTC颗粒可以牢固地抽滤在PVDF膜表面，热稳定性高且有较好的柔韧性。与抽滤前的PVDF膜相比，随着CuBTC颗粒的增多，膜厚度有所增加，孔径和孔隙率有所减小，但对其膜蒸馏膜通量的影响不大，且在CuBTC含量在0.6 g时表现出较好的性能。在以1 g/L原油和35 g/L氯化钠混合溶液为进料液对原膜和复合膜进行直接接触膜蒸馏抗油污实验，发现原膜很快被油污染堵塞毛孔，而复合膜具有良好的抗油污染能力，可以进行长期的膜蒸馏实验。     

Formation of C?X Bonds in CO2 Chemical Fixation Catalyzed by Metal−Organic Frameworks

Transformation of CO₂ based on metal−organic framework (MOF) catalysts is becoming a hot research topic, not only because it will help to reduce greenhouse gas emission, but also because it will allow for the production of valuable chemicals. In addition, a large number of impressive products have been synthesized by utilizing CO₂. In fact, it is the formation of new covalent bonds between CO₂ and substrate molecules that successfully result in CO₂ solidly inserting into the products, and only four types of new C X bonds, including C H, C C, C N, and C O bonds, are observed in this exploration. An overview of recent progress in constructing C X bonds for CO₂ conversion catalyzed by various MOF catalysts is provided. The catalytic mechanism of generating different C X bonds is further discussed according to both structural features of MOFs and the interactions among CO₂, substrates, as well as MOFs. The future opportunities and challenges in this field are also tentatively covered.     

Low-pressure-plasma-processed NiFe-MOFs/nickel foam as an efficient electrocatalyst for oxygen evolution reaction

A NiFe bimetallic metal organic framework (MOF) deposited on nickel foam and processed by low-pressure plasmas with 95%Ar+5%H₂, pure Ar, and 95%Ar+5%O₂ gases is used as an electrocatalyst for the oxygen evolution reaction. An alkaline solution (1 M KOH) with 95%Ar+5%H₂ plasma processed NiFe-MOFs/NF exhibits the best electrocatalytic performance with the lowest overpotential of 149 mV at a current density of 10 mA cm^?2 and a Tafel slope of 54 mV dec^?1. Furthermore, electrical impedance spectroscopy and cyclic voltammetry show that after 95%Ar+5%H₂ plasma treatment, the interfacial impedance greatly reduces, and the electrical double-layer capacitance slightly increased.     

Purified mesoporous nickel metal organic framework as electrocatalyst for hydrogen evolution reaction (HER) in basic medium

Metal organic framework or MOFs are found to be a good catalyst for hydrogen evolution in view of its excellent structural features like porous nature and well-defined morphology. This report describes the synthesis of Nickel-MOF prepared by solvothermal approach and further purified by a chemical process. Both impure and purified Nickel-MOFs are fabricated as electrodes for evaluating HER reaction. The performance towards electrocatalytic activity is affected due to the impurities present in the porous structure. In view of investigating the effect of activation/purification process towards morphology and in-turn HER activity, activation and purification is carried out to enhance the performance of MOFs. The electrochemical characterization proves high electrocatalytic activity for purified Ni-MOF with high rate kinetics towards HER than impure Ni-MOF. The Tafel slope of purified Nickel MOF is estimated to be 73.7 mV/dec with a low charge transfer resistance of 1.84 Ω, whereas the unpurified Ni-MOF shows 87.47 mV/dec and 3.85 Ω. Results show that pure Ni-MOF has abundant catalytic active edge sites and obeys Volmer-Heyrvosky mechanism with makes desorption of hydrogen as rate determining step.     

高性能的MOF/carbon复合材料对水溶液中铀酰的吸附

通过水热法和煅烧处理合成了金属有机框架/碳(MOF/carbon)，并用作吸附剂吸附水溶液中的U(Ⅵ)。研究了MOF/carbon在不同的pH、初始U(Ⅵ)浓度、反应时间下的吸附实验。结果表明：MOF/carbon对U(Ⅵ)的吸附能力远远高于单纯的MOF和碳，这主要归因于MOF/carbon丰富的表面吸附位点和MOF/carbon与U(Ⅵ)之间极强的静电吸引作用。基于Zeta和X射线光电子能谱分析发现，表面络合和静电作用可以为MOF/carbon吸附U(Ⅵ)提供一个非常合理的解释。热力学实验表明，U(Ⅵ)的去除是一个自发和吸热过程。此外，吸附动力学实验结果表明：U(Ⅵ)的吸附是一个快速并且高效的过程。这一发现为废水中U(Ⅵ)的消除和环境修复提供了一种高效吸附剂。