A novel 3D metal-organic framework(MOF) with remarkable thermal stability,Ni(BIC)2.2·5H2O(JUC-86)(HBIC = 1-H-benzimidazole-5-carboxylic acid and JUC = Jilin University China),has been synthesized under hydrothermal conditions.It crystallizes in tetragonal symmetry with P43212 space group.The 3D structure consists of channels assembled from triple helices with a 4.5 × 4.52 aperture,which are formed by the parallel alignment of three infinite helical chains.The thermogravimetric analysis(TGA) and powder X-ray diffractions(PXRD) indicate JUC-86 with high thermal stability(up to 350 ℃).
The introduction of electrospinning technique in synthesis of supported microporous membranes and films opens bright pro-spects for mass production and practical applications.This novel and promising strategy has wide suitable range for various substrates with the possibility of large-area processing.We successfully synthesized several kinds of microporous materials into high quality membranes and films on different shaped supports by this method,such as zeolite NaA and pure-silica-zeolite Beta membranes on porous A1203 tube,zeolite NaY membrane on stainless steel net and a metal-organic framework Eu(BTC)(H20)DMF(JUC-32)film on porous silica disc.X-ray diffraction(XRD)and scanning electron microscopy(SEM)were used as characterization means.The results verified the effectiveness of this new approach in fabrication of membranes and films.
金属有机骨架(Metal organic framework,MOF)配位聚合物作为一类重要的多孔材料具有诸多独特的性能.新型MOF材料的结构表征与确定一直是该研究领域的关键性研究问题.由于单晶X-射线衍射等结构测定方法对晶体尺寸有一定限制,小尺寸MOF新材料的晶体结构确定一直是亟待解决的科学难题.透射电子显微分析方法(Transmission electron microscopy,TEM)作为纳米尺寸晶体材料最有力的结构表征手段之一,已经被逐渐应用于MOF新材料领域,展现出了巨大的应用潜力.本文以几个国内外有代表性的工作为例,浅析TEM在MOF材料领域的发展现状.
采用一步水热法合成了棒状NiCo_2O_4前驱体,并通过调节水热反应过程中碳源(葡萄糖)的加入量以及后续热处理条件(气氛、温度)得到了一系列不同的NiCo_2O_4及NiCo_2O_4@C产物,并对这些产物的结构、形貌及电化学储锂性能进行了测试.结果表明,适当的葡萄糖加入量(0.5 g)配合合理的煅烧条件(400℃,氮气气氛)可以获得倍率性能和循环稳定性兼具的NiCo_2O_4@C纳米复合材料.在100 m A/g的电流密度下,该材料的首次充/放电比容量为634.1/767.2 m A·h/g,对应的库仑效率为82.7%,5周后的放电比容量为650.1 m A·h/g,容量保持率为84.74%,且在300 m A/g的高电流密度下可逆比容量仍可保持在225.9m A·h/g.
