Preparation and characterisation of CNF/MWCNT carbon aerogel as efficient adsorbents

In recent years, carbon aerogels have attracted much attention in basic research and as potential applications in many fields. Herein, the authors report a novel approach using bamboo powder as raw material to fabricate cellulose nanofibers (CNFs)/multi‐walled carbon nanotubes (MWCNTs) carbon aerogels by a simple dipping and carbonisation process. The developed material exhibits many exciting properties including low density (0.056 g cm⁻³), high porosity (95%), efficient capability for separation of oily droplets from water, and high adsorption capacity for a variety of oils and organic solvents by up to 110 times its own weight. Furthermore, the CNF/MWCNT carbon aerogels (CMCA) can be recycled many times by distillation and combustion, satisfying the requirements of practical oil‐water separation. Taken together with its economical, environmentally benign manufacturing process, sustainability of the precursor and versatility of material, the CMCA developed in this study will be a promising candidate for addressing the problems arising from the spills of oily compounds.Inspec keywords: aerogels, adsorption, nanofibres, filled polymers, nanocomposites, multi‐wall carbon nanotubes, porosity, drops, distillation, combustion, nanofabrication, polymer fibresOther keywords: CNF‐MWCNT carbon aerogel, adsorbents, bamboo powder, cellulose nanofibers, multiwalled carbon nanotubes, dipping, carbonisation, density, porosity, oily droplets, adsorption capacity, organic solvents, distillation, combustion, practical oil‐water separation, manufacturing process, sustainability, C     

超疏水性气凝胶粉体涂层的制备与性能

为提高建筑物表层的抗蚀性,将经三甲基氯硅烷(TMCS)改性过的疏水性SiO2气凝胶粉体溶于丙酮溶剂中,制成表面防护涂层。研究了不同温度对气凝胶疏水性能的影响,以及超疏水性气凝胶粉体涂层制备条件、涂刷于混凝土表层时对水的耐久性能;利用红外光谱和扫描电镜对其化学基团和微观形貌进行分析。实验结果表明,250℃以下时,气凝胶为超疏水性,之后随温度升高大幅度下降直到完全消失;涂刷次数与气凝胶在分散体系中的质量有关;冲刷时,涂层先由超疏水性变为疏水性,之后长时间保持不变,水浸泡不改变涂层的超疏水性。     

Facile preparation of superhydrophobic surface with high adhesive forces based carbon/silica composite films

Glass substrates modified by carbon/silica composites are fabricated through a two-step process for the preparation of a superhydrophobic surface (water contact angle ≥ 150°). Carbon nanoparticles were first prepared through a deposition process on glass using a hydrothermal synthesis route, then the glass was modified by SiO₂ using the hydrolysis reaction of tetraethylorthosilicate at room temperature. It is not only a facile method to create a superhydrophobic surface, but also helps to form a multi-functional surface with high adhesive forces.     

MWCNT/Lyocell炭纤维的制备及其性能

为了提高Lyocell基炭纤维的得率及其力学性能,纺制了MWCNT/Lyocell纤维并以此为原丝制备了炭纤维.采用广角X-衍射(WAXD)、热失重分析(TGA)、扫描电镜(SEM)、强度仪等分析了试样的结构与性能.结果表明:MWCNT/Lyocell纤维具有纤维素Ⅱ晶型的结构,纤维表面光滑且截面为圆形,符合优质炭纤维原幺幺的要求.以此为原丝所制炭纤维中,MWCNTs分布均匀;与纯Lyocell基炭纤维相比,掺杂MWCNTs的Lyocell基炭纤维的力学性能明显提高,其中,掺杂质量分数1％ MWCNTs的Lyocell基炭纤维的强度和模量分别比纯Lyocell基炭纤维提高70％和116％.同时掺杂MWCNTs还可以提高Lyocell纤维的热稳定性,进而提高Lyocell基炭纤维的得率.     

Electroconductive properties of zirconia/carbon nanotube aerogel composite

Electroconductive properties of zirconia/multiwalled carbon nanotube aerogel composite are investigated. The composite exhibits bulk percolation cluster-like conductivity at wide range of spatial scales. Conductive atomic force microscopy reveals the localized nature of conductive properties of the composite on the micro(nano)scopic scale and the uniformity of current distribution in all conductive areas independently of their size. The presence of unlinked conductive chains and the possibility of their linking by dissociating ions are demonstrated in experiments on registration of I–V curves during the evacuation of the composite impregnated with distilled water. The experimental data make it possible to describe the electrical properties of the composite as the properties of a circuit formed by the parallel connections of numerous voltage dividers arranged in a bulk porous structure. These features make the synthesized composite a promising candidate for use in catalysis and water vapor sensors.     

Controllable preparation of hierarchical porous carbon aerogel from liquefied wood for supercapacitors

Journal of Materials Science - Carbon aerogel (LWCA) with hierarchical porous was prepared from phenolated wood by self-assembling and one-step carbonization/activation process, and the pores...     

Synthesis and characterization of carbon/silica superhydrophobic multi-layer films

C/SiO₂ multi-layer films (3-layer films and 5-layer films) were obtained by sol-gel method and physical deposition on glass plates, and then heated at 500 °C for 1 h under a nitrogen atmosphere. The mechanical adhesive force with the substrate of the multi-layer films was sharply enhanced compared to the as-deposited amorphous carbon film. An absorption layer was formed on heat treated C/SiO₂ multi-layer films by modification of the surface with trimethylchlorosilane, and the wettability of the films changed from hydrophilic to super-hydrophobic. The structures of the physically deposited carbon and the multi-layer films were analyzed by X-ray diffraction, transmission electron microscopy and scanning electron microscopy. The experimental results showed that the 5-layer films had a concentric ring structure that caused the film to be superhydrophobic.     

Mechanical properties and toughness of carbon aerogel/epoxy polymer composites

Journal of Materials Science - Because of their nanoporous structure and large surface area, carbon aerogels have high potential for improving the material properties of polymer-based composites....     

间苯二酚-糠醛气凝胶的制备与表征

以氢氧化钠为催化剂和乙醇为溶剂合成间苯二酚-糠醛凝胶,经乙醇超临界干燥后得到有机气凝胶.间苯二酚与催化剂的摩尔比、间苯二酚与糠醛的摩尔比以及反应物总浓度等制备条件是影响有机气凝胶密度的主要因素.TEM和N2吸附法表明,有机气凝胶具有典型的三维纳米网络结构,网络颗粒约为10nm,平均孔径为7.8nm,其BET表面积和中孔体积分别为589 m2/g和1.106 cm3/g.     

碳气凝胶/四氧化三钴复合材料的制备及电化学性能

采用电化学沉积法,以碳气凝胶(CA)为基底沉积氢氧化钴(Co(OH)2),并热处理制备碳气凝胶/四氧化三钴(CA/Co3O4)复合电极材料。采用XRD,SEM对样品的结构和微观形貌进行表征。采用循环伏安,恒电流充放电测试,交流阻抗测试对样品的电化学性能进行了表征和测试。研究结果表明,采用电化学沉积法制备的CA/Co3O4复合电极材料,在电流密度0.5和5 A/g时,其质量比容量分别为1 020和646 F/g。可见Co3O4的复合,能够很大程度的提升电化学性能。     

花生壳纳米纤维素超疏水气凝胶的制备及在棉织物上的应用

以花生壳粉为原料,通过化学机械法从中提取纳米纤维素,采用溶胶-凝胶法,在花生壳纳米纤维素悬浮液中加入甲基三甲氧基硅烷以对其进行改性,并采用冷冻干燥法最终制备了纳米纤维素超疏水气凝胶.将通过喷涂的方法使纳米纤维素超疏水气凝胶和聚二甲基硅氧烷(PDMS)整理到棉织物上,分别对超疏水气凝胶和超疏水棉织物进行分析和表征.结果表...     

三种碳源对CNF/AC复合材料性能的影响

采用甲烷、正丁烷、乙炔3种烃类气体作为碳源,纳米金属镍为催化剂,在活性炭(AC)上生长了纳米碳纤维(CNF)。通过氮气等温吸附、粉末比电阻、扫描电镜(SEM)和X光衍射(XRD)等一系列表征手段,比较了3种碳源对获得的CNF/AC复合材料的比表面积、导电性,以及其中的CNF形貌的影响。结果表明,在相同生长条件下,碳沉积速度与碳源气的碳氢比成正相关,与产物的比表面积成负相关。提出碳源气在化学气相沉积(CVD)过程对产物性能影响的机理,提出依据分子中碳气原子比选择烃类碳源气,从而提高CVD过程催化分解反应选择性的方法。     

聚吡咯/硝酸活化碳气凝胶复合材料在超级电容器中的应用

用溶胶-凝胶法制备出碳气凝胶,对其进行硝酸活化,与聚吡咯复合(化学氧化聚合法)及先活化后复合,探究活化、复合对碳气凝胶性能的影响。采用傅立叶变换红外光谱仪和扫描电子显微镜表征材料的成分和形貌,通过循环伏安法、恒流充放电、交流阻抗及循环性测试等考察材料的电化学性能。结果表明,最佳处理方式为先活化后复合。比电容量大大提高,约为纯碳气凝胶的3倍,扫描速率为5mV/s时,比电容量达311F/g;1000次循环后比电容稳定在较高数值;导电性也得到提高。     

SiO2气凝胶/中间相沥青基泡沫炭复合材料的制备与表征

以正硅酸乙酯、乙醇和去离子水为原料,采用溶胶-凝胶法制备了SiO2溶胶;并以煤沥青为原料,采用自挥发发泡法制备了中间相沥青基泡沫炭。然后采用浸渍工艺将SiO2溶胶和中间相沥青基泡沫炭在常压下进行复合,制备了SiO2气凝胶/中间相沥青基泡沫炭复合隔热材料。利用XRD、SEM、热导仪和万能试验机等设备分别研究了SiO2气凝胶、中间相沥青基泡沫炭以及SiO2气凝胶/中间相沥青基泡沫炭复合材料的结构和性能。结果表明,所制备的复合材料具有一定的力学性能,同时其隔热性能优于单一泡沫炭的隔热性能,有望成为一种新型的隔热材料。     

MWCNT synthesis over Fe-BTC as a catalyst/carbon source via CVD

A Fe-BTC (benzene-1,3,5-tricarboxylate) metal-organic framework was used for the first time as a combined catalyst and carbon source for the synthesis of multi-walled carbon nanotubes (MWCNTs). Decomposition of acetylene in the presence of Fe-BTC by the CVD method at 700 to 900 °C led to successful production of high purity as-grown CNT products in high yield.     

Effect of carbon nanofibres dispersion on the microwave absorbing properties of CNF/epoxy composites

Since mid-twentieth century filled polymers have been largely studied for electromagnetic (e.m.) applications, including wave absorbing materials, showing good promise. A certain knowledge was gained in the field of carbon particles filled polymers, even if there is still a lack of understanding the relationship between material microstructure and macroscopic electromagnetic performance. Moreover, the recent discover of carbon nanofibres and nanotubes, with their potentiality, introduces new field of investigation. In this work carbon nanofibers were used to increase permittivity of neat resin, in order to achieve better absorbing performance in the 8–20 GHz range. Carbon nanofibers were chosen as a way of lowering filler content, while increasing the dielectric properties of the resulting composite. Key factor is the nanofiller dispersion process: in this paper two different dispersion methods were used, both employing an organic solvent that was removed either via evaporation or filtration. The resulting microstructures, composed of well dispersed CNF as well as of microaggregates, lead to materials that, on equal filler content, present different dielectric properties and absorbing performance. Microstructures were analyzed by SEM.     

炭气凝胶/活性炭复合电极在有机电解液体系双电层电容器中的阻抗

分别以炭气凝胶(CAG),炭黑(CB)以及石墨(G)为导电剂与KOH活化法高比表面积活性炭(HSAC)制备复合电极,组装成双电层电容器,在(C2H5)4NBF4/丙烯碳酸盐电解液体系中进行交流阻抗测试分析。应用动力学及电子传递控制的等效电路模型对各电极的实验阻抗数据进行拟合得到相应的模型参数,串联溶液电阻Rs、极化电阻Rp、能斯特边界层厚度δ及平均孔内离子扩散系数D。结果表明,炭气凝胶复合电极的孔内离子扩散系数D最高,极化电阻Rp与炭黑复合电极接近。炭气凝胶电极的内阻为各电极中最低并且具有最高的比电容。     

炭气凝胶微球的凝胶化机理

以间苯二酚和甲醛为原料,溴化十六烷三甲基铵为催化剂,通过反相悬浮聚合法成功制备了炭气凝胶微球.研究了反应体系的黏度、酸度、温度以及反应中间产物紫外光谱的变化情况,探讨该凝胶反应的作用机理.结果表明:凝胶反应是一个酚醛缩合过程,其反应历程可以分为线性缩聚、交联、胶粒生长和宏观凝胶化四个阶段.     

制备工艺条件对板式纳米碳纤维形貌和结构的影响

化学气相沉积法制备的纳米碳纤维(CNF)的形貌和结构取决于其制备工艺条件,包括催化剂的组成,制备温度和碳源的组成等.本文以纳米级的Fe3O4粉末为催化剂,CO为碳源,制备CNF,通过高分辨率透射电镜、N2吸附及热重分析考察制备工艺条件对CNF形貌和结构的影响.研究发现,生长温度越高,CNF的表面积和孔客逐渐减小,但仍属于板式纳米碳纤维.还原温度和H2浓度对CNF的形貌和微观结构影响较大,过低的还原温度会导致螺旋状CNF生成.