Control of Porosity by Using Isoreticular Zeolitic Imidazolate Frameworks (IRZIFs) as a Template for Porous Carbon Synthesis

Herein, by using isoreticular zeolitic imidazolate frameworks (IRZIFs) as a template, we report the synthesis, morphology, and gas adsorption properties of porous carbon synthesized by a nanocasting method at 1000?°C, in which furfuryl alcohol (FA) was used as a carbon source. By using IRZIFs with variable porosity as templates, we could achieve control over the carbon porosity and H(2) and CO(2) uptake. The resultant microporous carbon C-70, synthesized by using ZIF-70 as the template, is the most porous (Brunauer-Emmett-Teller (BET) surface area 1510?m(2) g(-1) ). Carbon C-68, synthesized by using ZIF-68, has moderate porosity (BET surface area 1311?m(2) g(-1) ), and C-69, synthesized by using ZIF-69, has the lowest porosity in this series (BET surface area 1171?m(2) g(-1) ). The porous carbons C-70, C-68, and C-69, which have graphitic texture, have promising H(2) uptake capacities of 2.37, 2.15, and 1.96?wt?%, respectively, at 77?K and 1?atm. Additionally, C-70, C-68, and C-69 show CO(2) uptake capacities of 5.45, 4.98, and 4.54?mmol?g(-1) , respectively, at 273?K and 1?atm. The gas uptake trends shown by C-70, C-68, and C-69 clearly indicate the dependence of carbon porosity on the host template. Moreover, the as-synthesized carbons C-70, C-68, and C-69 show variable conductivity.     

沸石咪唑酯骨架结构材料ZIF-8催化Friedel-Crafts酰基化反应(英文)

A zeolite imidazolate framework,ZIF-8,was synthesized and characterized by dynamic laser light scattering,X-ray powder diffraction,scanning electron microscopy,transmission electron microscopy,thermogr...     

Postsynthetic modification of a metal-organic framework for stabilization of a hemiaminal and ammonia uptake

In our study, we show by solid-state (15)N NMR measurements that an important zirconium metal-organic framework (UiO-66) with amino-functionalized links is composed of a mixture of amino and -NH(3)(+)Cl(-) salt functionalities rather than all amino functionality to give a composition of Zr(6)O(4)(OH)(4)(BDC-NH(2))(4)(BDC-NH(3)(+)Cl(-))(2) (UiO-66-A). UiO-66-A was postsynthetically modified to form a mixture of three functionalities, where the hemiaminal functionality is the majority species in UiO-66-B and aziridine is the majority functionality in UiO-66-C. UiO-66-A-C are all porous with surface areas ranging from 780 to 820 m(2)/g and have chemical stability, as evidenced by reversible ammonia uptake and release showing capacities ranging from 134 to 193 cm(3)/g.     

多孔材料表面修饰聚酰亚胺非对称混合基质膜对CO2/N2和CO2/CH4的气体分离

兼具高通量和高选择性的气体分离膜是研究膜分离材料的目标.采用相转化法制备了聚酰亚胺非对称膜,并将其作为基底膜材料,分别在其表面修饰掺有金属有机框架材料Cu₃(BTC)₂ (1, 3, 5-均苯三甲酸合铜),沸石咪唑酯骨架材料ZIF-8以及镁铝水滑石MgAl-LDHs的聚酰胺酸溶液,经热亚胺化后制成非对称混合基质膜.研究了该系列非对称混合基质膜的结构特性和对CO₂、CH₄和N₂气体分离性能;考察了ZIF-8的掺杂量对非对称混合基质膜透气性能的影响.结果表明非对称聚酰亚胺膜的表面修饰可有效地改变膜的表面性质,掺杂ZIF-8的非对称混合基质膜气体的透气性能和选择性都增加,且掺杂量为5% (w)时CO₂/N₂和CO₂/CH₄的理想选择性分别高达24和83,为合成高效的CO₂分离膜提供了借鉴.     

Metal–organic framework derived hierarchical porous TiO_2 nanopills as a super stable anode for Na-ion batteries

Hierarchical porous TiO_2 nanopills were synthesized using a titanium metal-organic framework MIL-125(Ti) as precursor. The as-synthesized TiO_2 nanopills owned a large specific surface area of 102 m~2/g and unique porous structure. Furthermore, the obtained TiO_2 nanopills were applied as anode materials for Na-ion batteries for the first time. The as-synthesized TiO_2 nanopills achieved a high discharge capacity of 196.4 m Ah/g at a current density of 0.1 A/g. A discharge capacity of 115.9 m Ah/g was obtained at a high current density of 0.5 A/g and the capacity retention was remained as high as 90% even after 3000 cycles. The excellent electrochemical performance can be attributed to its unique hierarchical porous feature.     

Porous magnesium carboxylate framework: synthesis, X-ray crystal structure, gas adsorption property and heterogeneous catalytic aldol condensation reaction

A new three-dimensional alkaline-earth metal-organic framework (MOF) compound, [Mg(Pdc)(H(2)O)](n) (1) (H(2)Pdc = pyridine-2,5-dicarboxylic acid), has been synthesized and structurally characterized by single crystal X-ray diffraction analysis. Compound 1 features a 3D porous framework afforded by the Mg(2)-diad centers through formation of interconnected chair like structural motifs. A nitrogen adsorption study confirms the microporosity of compound 1 with a BET surface area of 211 ± 12 m(2) g(-1). Upon dehydration, the BET surface area of 1 is enhanced to a value of 463 ± 36 m(2) g(-1) due to removal of coordinated water molecule. After rehydration, the compound reverts to its original form as evidenced by powder X-ray diffraction and IR spectroscopic analysis and N(2) sorption measurement. Compound 1 retains its pore structure with a variable BET surface area in several cycles of dehydration and rehydration processes indicating robustness of the framework in [Mg(Pdc)(H(2)O)](n) (1). Compound 1 catalyzes the aldol condensation reactions of various aromatic aldehydes with acetone and cyclohexanone in heterogeneous conditions. Notably, the catalytic activity of the compound is enhanced upon dehydration. The catalyst can be recycled and reused several times without significant loss of activity.     

Quest for highly porous metal-metalloporphyrin framework based upon a custom-designed octatopic porphyrin ligand

A porous metal-metalloporphyrin framework, MMPF-2, has been constructed from a custom-designed octatopic porphyrin ligand, tetrakis(3,5-dicarboxyphenyl)porphine, that links a distorted cobalt trigonal prism secondary building unit. MMPF-2 possesses permanent microporosity with the highest surface area of 2037 m(2) g(-1) among reported porphyrin-based MOFs, and demonstrates a high uptake capacity of 170 cm(3) g(-1) CO(2) at 273 K and 1 bar.     

A zeolitic porous lithium-organic framework constructed from cubane clusters

Reported here is a lithium cubane based zeolitic framework possessing a multi-dimensional channel system. The unique design strategy of adopting the ditopic ligand 4-pyridinol leads to a rigid porous framework with high thermal stability. It has a BET surface area of 440.3 m(2) g(-1) and a H(2) uptake capacity of 108.7 cm(3) g(-1) at 77 K.     

不同尺寸ZIF-8对U(VI)的吸附性能

以经典的金属有机骨架(MOFs)材料ZIF-8为吸附剂,研究尺寸效应对铀吸附性能的影响。 通过3种方法合成不同粒径的ZIF-8,利用扫描电子显微镜(SEM)、X射线粉末衍射仪(XRD)、表面积与孔隙度分析仪等对其进行了表征,测试了相同条件下不同尺寸的ZIF-8对硝酸铀酰溶液中U(VI)吸附,分别对其吸附过程的动力学和吸附等温线进行了考察,并测试了材料的可重复利用性。 结果表明,成功制备了高结晶性、高纯度的ZIF-8,产物形貌呈菱形十二面体,颗粒均匀,粒径分别为约50 nm、150 nm及2 μm;3种ZIF-8具有单一均匀的微孔结构和与粒径高度相关的比表面积;不同尺寸的ZIF-8均能快速吸附溶液中的U(VI),在室温pH=3下,在70 min左右时即可吸附初始质量浓度为200 mg/L的U(VI)溶液中90%以上U(VI);其中较小尺寸(约50 nm)的ZIF-8吸附性能最好,单位质量ZIF-8吸附U(VI)的饱和吸附量达到520.26 mg/g;ZIF-8对U的吸附动力学上符合二级动力学方程,吸附等温线符合Langmuir模型,说明ZIF-8对U(VI)的捕获属于化学单层吸附;经过4个吸附-解吸循环后,3种尺寸的ZIF-8均依然保持了70%以上的去除率。     

Synthesis and characterization of a 1-D porous barium carboxylate coordination polymer, [Ba(HBTB)] (H3BTB = benzene-1,3,5-trisbenzoic acid)

The synthesis and characterization of [Ba(HBTB)] is reported. This is the first porous framework synthesized with barium using carboxylate ligands. The framework has robust microporous character (Langmuir surface area of 879 m(2) g(-1)) and possesses unsaturated metal sites when fully desolvated.     

A ZIF-8 Host for Dendrite-Free Zinc Anodes and N,O Dual-doped Carbon Cathodes for High-Performance Zinc-Ion Hybrid Capacitors

Zn is a promising anode for aqueous energy storage owing to it intrinsic superior properties such as large capacity, abundant reserves, low potential and safety. But, the growth of dendrites during charge and discharge leads to a decrease in reversibility. In addition, further development of zinc-ion hybrid capacitors (ZICs) is seriously challenging because of the lack of an exceptional cathode. Herein, we use ZIF-8 annealed at 500 °C (annealed ZIF-8) as a host material for stable and dendrite-free Zn anodes. Utilization of annealed ZIF-8 results in dendrite-free Zn deposition and stripping as a result of its porous construction, which contains trace Zn. Furthermore, we firstly proposed innovative N,O dual-doped carbon which was designed by the derived ZIF-8 (ZIF-8 derived C) as cathode for high-energy and power-density ZICs. The new ZIC assembled by Zn@annealed ZIF-8 anode and ZIF-8 derived C cathode provides a capacity of 135.5 mAh g⁻¹ and an energy density of 108.4 Wh kg⁻¹ with a power density of 800 W kg⁻¹ at 1.0 A g⁻¹. In addition, it shows outstanding cycling stability of 91% capacity retention after 6000 cycles at 5.0 A g⁻¹. Moreover, the solid-state ZICs can drive LEDs and smart watches. This ZIC holds promise for the practical application of supercapacitors.     

氮杂碳原位包覆Cu2O/Co3O4@C异质结构复合材料的设计构筑及高效储锂性能

通过液相法合成了Cu₂O纳米立方体, 并在其基础上利用金属有机框架化合物(MOFs)的自组装形貌调控, 进一步构建了层级多孔Co₃O₄和氮杂碳双壳层的Cu₂O/Co₃O₄@C异质结构复合材料. 利用X射线衍射(XRD)、 扫描电子显微镜(SEM)、 透射电子显微镜(TEM)、 热重分析(TGA)、 BET比表面积及孔径分析、 拉曼光谱和X射线光电子能谱(XPS)等表征手段证实了Cu₂O/Co₃O₄@C异质结构复合材料的成功构筑. 双壳层结构设计和丰富的层级孔道结构有效抑制了材料在充放电循环过程中的体积膨胀, 材料在循环100次后仍保持了原有的形貌和构造. 表面多孔结构对电解液的充分浸润、 异质结构的界面内建电场以及缺陷氮杂碳的表面包覆有效提升了材料的电子和离子导电能力. 异质结构设计、 形貌调控、 多孔特性和氮杂碳的协同作用, 使得Cu₂O/Co₃O₄@C复合材料呈现出优异的电化学性能, 在0.1 A/g电流密度下的首次放电比容量达到2065 mA·h/g, 在 2 A/g电流密度下的可逆放电比容量高于360 mA·h/g, 在1 A/g电流密度下循环350次后仍有530 mA·h/g的高可逆放电比容量.     

Gram-scale synthesis of nanomesh graphene with high surface area and its application in supercapacitor electrodes

Graphene that had nanomeshes, only one to two graphene layers, and specific surface areas of up to 1654 m(2) g(-1) was produced on gram-scale by template growth on porous MgO layers. Its unique porous structure gave excellent electrochemical capacitance (up to 255 F g(-1)), cycle stability and rate performance.     

ZIF-67@Cellulose nanofiber hybrid membrane with controlled porosity for use as Li-ion battery separator

Zeolitic imidazolate framework-67(ZIF-67) was synthesized on the surface of cellulose nanofibers(CNFs)in methonal to address the problems of unhomogeneous pore size and pore distribution of pure CNF membrane.A combination of Energy Dispersive X-Ray Spectroscopy(EDS),X-ray photoelectron spectroscopy(XPS) and X-ray powder diffraction(XRD) patterns were used to determine the successful synthesis of ZIF-67@CNFs.The size of the ZIF-67 particles and pore size of the ZIF-67@CNF membrane were50-200 nm and 150-350 nm, respectively.The prepared ZIF-67@CNF membrane exhibited excellent thermal stability,lower thermal shrinkage and high surface wettability.The discharge capacity retention of the Li-ion batteries(LIBs) made with ZIF-67@CNF,glass fiber(GF),CNF and commercial polymer membranes after 100 th cycle at 0.5 C rate were 88.41%,86.22%,83.27%,and 81.03%,respectively.LIBs with ZIF-67@CNF membrane exhibited a better rate capability than these with other membranes.No damage of porous structure or peel-off of ZIF-67 was observed in the SEM images of ZIF-67@CNF membrane after100 th cycle.The improved cycling performance,rate capability,and good electrochemical stability implied that ZIF-67@CNFs membrane can be considered as a good alternative LIB separator.     

ZIF-8基复合材料高效、稳定电催化还原CO2

电催化CO₂还原反应(eCO₂RR)受到催化剂本征活性以及传质的限制，导致材料的催化活性低、反应起始电位高等问题。我们以类沸石锌盐咪唑骨架(ZIF-8)材料为研究对象，探究了不同粒径ZIF-8材料的eCO₂RR性能。优选粒径为50 nm的ZIF-8材料，进一步引入碳纳米管(CNT)作为其导电基底材料，通过原位生长，构建了复合材料ZIF-8-50@CNT的多级孔结构和疏水界面。eCO₂RR实验结果表明，CNT的引入提高了催化剂的导电性，优化后的复合材料有效地降低了反应的起始电位。在-1.1 V (相对可逆氢电极(RHE))电位下，CO部分电流密度为15.6 mA·cm^-2，ZIF-8-50@CNT催化剂的比表面活性提升了3.5倍(相比ZIF-8-50)，塔菲尔斜率降低到136 mV·dec^-1。并且产物CO的选择性和稳定性得到了提高，在宽电势窗口-0.9~-1.2 V (vs RHE)内，CO的法拉第效率(FE)保持在80%以上。在10 h稳定性测试中，催化剂活性保持稳定，整体增强了复合材料eCO₂RR的性能。     

ZIF-8基复合材料高效、稳定电催化还原CO2

电催化CO₂还原反应(eCO₂RR)受到催化剂本征活性以及传质的限制,导致材料的催化活性低、反应起始电位高等问题。我们以类沸石锌盐咪唑骨架(ZIF-8)材料为研究对象,探究了不同粒径ZIF-8材料的eCO₂RR性能。优选粒径为50 nm的ZIF-8材料,进一步引入碳纳米管(CNT)作为其导电基底材料,通过原位生长,构建了复合材料ZIF-8-50@CNT的多级孔结构和疏水界面。eCO₂RR实验结果表明,CNT的引入提高了催化剂的导电性,优化后的复合材料有效地降低了反应的起始电位。在-1.1 V(相对可逆氢电极(RHE))电位下,CO部分电流密度为15.6 mA·cm^-2,ZIF-8-50@CNT催化剂的比表面活性提升了3.5倍(相比ZIF-8-50),塔菲尔斜率降低到136 mV·dec^-1。并且产物CO的选择性和稳定性得到了提高,在宽电势窗口-0.9～-1.2 V(vs RHE)内,CO的法拉第效率(FE)保持在80%以上。在10 h稳定性测试中,催化剂活...     

Ultra-small Size ZIF-8 Materials for Efficient and Selective Electrocatalytic Reduction of CO2 to CO

Zeolitic Imidazolate Frameworks (ZIFs) are considered as a novel porous material combining high stability in inorganic zeolites with high porosity and organic functionality of MOFs. The cage-like structure selectively and efficiently traps CO₂, which is an indispensable and critical step for Electrocatalytic CO₂ Reduction Reaction (CO₂RR). In this work, ultrasmall ZIF-8 nanomaterials are synthesized by tuning the molar ratio of the feedstock and used as electrocatalysts for the selective reduction of CO₂ to CO. The catalytic activity of the ultra-small size ZIF-8 material for the electrocatalytic reduction of CO₂ can reach satisfactory results with a Faraday efficiency of 91 % for CO and a stability of 12.5 h at a high applied potential of −1.8 V vs. RHE. The investigation can provide a new idea to explore for the design and improvement of catalysts for CO₂RR.     

Effects of raw material texture and activation manner on surface area of porous carbons derived from biomass resources

Porous carbons have been prepared from biomass resources, such as cornstalks, rice straws, pine needles and pinecone hulls, through a simple carbonization and KOH solution activation process. The pore sizes of the obtained porous carbons are mainly distributed in the range of 1-2 nm, whereas the surface areas of the materials vary from 1000 to more than 3000 m(2) g(-1) depending on the raw materials and preparation conditions. It is found that the biomass texture and the activation manner play key roles in determination of surface areas of the porous carbons. In addition, the amount of activation agent, the activation temperature and the activation time also affect the surface area of the porous carbons but to a less extent. The obtained porous carbons with high surface areas show good performance when used as Pt-catalyst supports for cinanamaldehyde hydrogenation.     

Amorphization of the prototypical zeolitic imidazolate framework ZIF-8 by ball-milling

We report the rapid amorphization of the prototypical substituted zeolitic imidazolate framework, ZIF-8, by ball-milling. The resultant amorphous ZIF-8 (a(m)ZIF-8) possesses a continuous random network (CRN) topology with a higher density and a lower porosity than its crystalline counterpart. A decrease in thermal stability upon amorphization is also evident.     

Metal-organic framework materials with ultrahigh surface areas: is the sky the limit?

We have synthesized, characterized, and computationally simulated/validated the behavior of two new metal-organic framework (MOF) materials displaying the highest experimental Brunauer-Emmett-Teller (BET) surface areas of any porous materials reported to date (～7000 m(2)/g). Key to evacuating the initially solvent-filled materials without pore collapse, and thereby accessing the ultrahigh areas, is the use of a supercritical CO(2) activation technique. Additionally, we demonstrate computationally that by shifting from phenyl groups to "space efficient" acetylene moieties as linker expansion units, the hypothetical maximum surface area for a MOF material is substantially greater than previously envisioned (～14600 m(2)/g (or greater) versus ～10500 m(2)/g).