Extrusion 3D printing of carbon nanotube-assembled carbon aerogel nanocomposites with high electrical conductivity

Carbon nanotubes(CNTs)with high aspect ratio and excellent electrical conduction offer huge functional improvements for current carbon aerogels.However,there remains a major challenge for achieving the on-demand shaping of carbon aerogels with tailored micro-nano structural textures and geometric features.Herein,a facile extrusion 3D printing strategy has been proposed for fabricating CNT-assembled carbon(CNT/C)aerogel nanocomposites through the extrusion printing of pseudoplastic carbomer-based inks,in which the stable dispersion of CNT nanofibers has been achieved relying on the high viscosity of carbomer microgels.After extrusion printing,the chemical solidification through polymerizing RF sols enables 3D-printed aerogel nanocomposites to display high shape fidelity in macroscopic geometries.Benefiting from the micro-nano scale assembly of CNT nanofiber networks and carbon nanoparticle networks in composite phases,3D-printed CNT/C aerogels exhibit enhanced mechanical strength(fracture strength,0.79 MPa)and typical porous structure characteristics,including low density(0.220 g cm^(-3)),high surface area(298.4 m^(2)g^(-1)),and concentrated pore diameter distribution(~32.8nm).More importantly,CNT nanofibers provide an efficient electron transport pathway,imparting 3D-printed CNT/C aerogel composites with a high electrical conductivity of 1.49 S cm^(-1).Our work would offer feasible guidelines for the design and fabrication of shape-dominated functional materials by additive manufacturing.

Assembling ionic liquid into porous molecular filler of mixed matrix membrane to trigger high gas permeability,selectivity,and stability for CO_(2)/CH_(4) separation

As an emerging zero-dimensional nano crystalline porous material,porous organic cages(POCs)with soluble properties in organic solvents,are promising candidates as molecular fillers in mixed matrix membranes(MMMs).The pore structure of POCs should be adjusted to trigger efficient gas separation performance,and the interaction between filler and matrix should be optimized.In this work,ionic liquid(IL)was introduced into the molecular fillers of CC3,to construct the IL@CC3/PIM-1 membrane to effectively separate CO_(2) from CH_(4).The advantages of doping IL include:(1)narrowing the cavity size of POCs from 4.4 to 3.9Åto enhance the diffusion selectivity,(2)strengthening the CO_(2) solubility to heighten the gas permeability,and(3)improving the compatibility between filler and matrix to upgrade membrane stability.After the optimization of the membrane composite,the IL@CC3/PIM-1-10%membrane possesses the CO_(2) permeability of 7868 Barrer and the CO_(2)/CH_(4) selectivity of 73.4,which compared to the CC3/PIM-1-10%membrane,improved by 15.9%and 106.2%,respectively.Furthermore,the membrane has maintained a stable separation performance at varied temperatures and pressures during the long-term test.The proposed method offers an efficient way to improve the performance of POCs-based MMMs in gas separation.

Genetic Variation of the Novel Badnaviruses Infecting Nelumbo Nucifera Based on the RT/RNase H Coding Region Sequences

Lotus(Nelumbo nucifera Gaertn.)is an economically important perennial aquatic herb plant in China.Presently,viral diseases caused by Cucumber mosaic virus(CMV)and Dasheen mosaic virus(DsMV)are detected in lotus.In this study,the putatively novel badnaviruses from lotus plants(LBVs)were identified using next-generation sequencing of siRNAs and conventional Sanger sequencing based on the RT/RNase H coding region sequences.Lotus plants infected by LBVs harbored virus quasispecies.A unique recombination event of LBVs was found in a single lotus plant.Sap inoculation showed that LBVs could actively replicate in the lotus plants,but without a wide host range.The field survey of 43 lotus plants in Jiangsu Province showed a prevalence of 62.8%for LBVs,confirming that it is widely distributed in Jiangsu Province of China.

氧化物气凝胶高温红外改性研究

氧化物气凝胶是一类具有超低热导率的新型纳米多孔材料,在航空航天等高温隔热领域具有广阔的应用前景。然而目前常见的氧化硅、氧化铝等氧化物气凝胶受材料/结构单元固有性质的限制,其通常具有红外透明性,而高温下辐射传热占据主导地位,大量红外辐射会透过气凝胶,热导率急剧攀升,导致其高温隔热性能较差,因此需要对其进行高温红外改性,从而满足更高的隔热性能需求。本文综述了近年来添加遮光剂、纤维及调整气凝胶的结构/形貌在提高氧化物气凝胶高温隔热性能方面的研究进展,并对未来研究方向进行展望。

基于水性气相二氧化硅浆料制备柔性二氧化硅气凝胶复合毡

二氧化硅气凝胶由于其低导热率在隔热应用方面具有巨大的潜力.然而,它们通常具有较差的机械性能,需要在保持低热导率的同时增强机械性能.本研究以商业化气相二氧化硅和甲基三甲氧基硅烷为硅源,并以水和乙醇为溶剂形成浆料.基于此,二氧化硅气凝胶块体(SAMs)可通过常压干燥进行制备,且无需额外的表面改性或溶剂置换.制备的SAMs保持了典型的纳米孔结构,具有低密度(0.24 g cm^(-3))、收缩率(4%)和热导率(0.046 W m^(-1)K^(-1)).通过辊压将浆料浸渍到纤维毡中,并通过浆料热固化和常压干燥制备出二氧化硅气凝胶毡(SABs).制备的SABs具有良好的柔韧性和机械性能,便于安装和隔热应用,并显著减少了生产周期和成本.此外,基于SAMs的纳米孔结构和低收缩率,通过调控遮光剂的粒径和质量分数进一步降低了SABs的高温热导率,优化后的SABs在800℃的热导率低至0.054 W m^(-1)K^(-1).

Constructing ultrastable electrode/electrolyte interface for rapid potassium ion storage capability via salt chemistry and interfacial engineering

Conversion/alloying anode materials exhibiting high K storage capacities suffer from large volume variations and unstable electrode/electrolyte interfaces upon cycling.Herein,taking SnS/reduced graphene oxide(SnS/rGO)anodes as an example,the electrochemical performance of SnS/rGO could significantly be improved via employing potassium bis(fluorosulfonyl)imide(KFSI)salt in electrolytes and ultrathin TiO_(2) coating.KF-rich inorganic layer was demonstrated to help form robust SEI layer,which could suppress the side reactions to increase the Coulombic efficiency.The formed potassiated K_(x)TiO_(2) coating layer was constructed to boost charge transfer capability and K-ion diffusion kinetics.The as-prepared SnS/rGO@TiO_(2)-20 electrode in KFSI electrolyte delivers the high CE of 99.1%and 424 mAh·g^(−1) after 200 cycles with an ultrahigh capacity retention of 98.5%.

Continuous synthesis for zirconium metal-organic frameworks with high quality and productivity via microdroplet flow reaction

Zirconium metal-organic frameworks（Zr-MOFs） represent the most promising candidates among MOFs for industrial utilizations owing to their high porosity and excellent stability. However, the efficient synthesis of Zr-MOFs combining with continuous production, high productivity and good product quality still remains a critical issue for practical applications. Herein, we report an efficient method of synthesizing a series of Zr-MOFs through a microdroplet flow reaction, which is more accommodate the requirements of industrial production. Four types of Zr-based MOFs with different ligands and topologies（MOF-801, MOF-804, DUT-67 and MOF-808） were produced as a pure phase of high quality crystalline with uniform morphologies. Furthermore, this series of Zr-MOFs were obtained in a continuous way and at a space-time yield（STY） highly up to 367.2 kg m-3 d-1. These MOFs exhibit the similar pore structure and thermal stability with that prepared from conventional solvothermal synthesis. CO2 sorption studies on these MOFs demonstrate that the hydroxyl groups on ligand can render MOFs with high CO2/N2 selectivity.

超轻纳米纤维气凝胶的制备及其应用

超轻纳米纤维气凝胶是一种以一维纳米纤维为基本构筑单元的新型气凝胶材料,相比于传统气凝胶,其不仅具有更高的孔隙率和更低的密度,还拥有更优异的机械性能和理化性质,因此该材料的先进制备技术和在新兴领域的创新性应用是近年来超轻气凝胶领域的研究热点。本文结合国内外研究现状,按照材料体系分类系统综述了超轻纤维气凝胶的制备方法、结构特点以及在隔热、吸附、电化学、传感和生物医学等领域的重要应用,提出了现阶段该材料面临的一些挑战,并展望了其在未来的发展方向。

金刚烷基微孔有机聚合物的合成与性能

微孔有机聚合物由于具有优异的热稳定性、化学稳定性、低密度、高比表面积、分子尺度的孔径分布等优点,在气体储存、气体吸附与分离、有机蒸气吸附、异相催化剂载体、水处理、功能材料等方面引起研究者们极大的兴趣。通常,分子构筑单元特别是在平面或空间中呈对称性的单元,是合成微孔有机聚合物的核心单位。在众多的构筑单元或单体中,多取代金刚烷化合物具有高空间对称性和刚性结构特点,已被成功地用作分子“结”与其他多种类型的连接单元(分子“杆”)来构建三维微孔有机聚合物,而且此类微孔有机聚合物在合成产率、结构稳定性、孔径分布、吸附分离等方面表现出许多特殊或优异的性质。本文介绍了目前由金刚烷结构单元构建的以下几种微孔有机聚合物在合成和性能方面的研究进展:苯环连接型、席夫碱连接型、酰亚胺连接型、富氮型(苯并咪唑和三嗪),详细分析和比较了这些聚合物在合成方法、结构特点、稳定性与吸附性能等方面的异同点。此外,介绍了几种其他新型的金刚烷基聚合物。最后提出基于金刚烷的微孔有机聚合物未来的研究方向与思路。