碳纳米管吸波材料研究进展

介绍了碳纳米管的结构和性能特点,归纳和分析了碳纳米管吸波材料的最新进展,并提出了现有研究中存在的不足及进一步研究的方向。目前碳纳米管吸波材料的研究主要集中在不同结构碳纳米管吸波材料、磁性金属/碳纳米管复合吸波材料、稀土/碳纳米管复合吸波材料、铁氧体/碳纳米管复合吸波材料、聚合物/碳纳米管复合吸波材料以及陶瓷/碳纳米管复合吸波材料。对碳纳米管进行形貌控制、结构优化、表面修饰、复合掺杂改性以及界面结合和耐温性能的强化,是碳纳米管吸波材料今后的发展方向。     

含碳纳米管微波吸收材料的制备及其微波吸收性能研究

用竖式炉流动法,以二茂铁为催化剂,噻吩为助催化剂,苯为碳源通过催化裂解反应制备了碳纳米管,碳纳米管的外径为20-50nm,内径10-30nm,长度50-1000μm.分别以碳纳米管、羰基铁粉、碳纳米管与羰基铁粉的混合物为吸收剂制备了微波吸收材料,研究了上述三种微波吸收材料在2-18GHz的吸波性能,与纯碳纳米管和纯羰基铁粉微波吸收材料相比, 碳纳米管与羰基铁粉复合微波吸收材料在2-18GHz的吸收峰明显向低频移动.在含碳纳米管的微波吸收材料中,碳纳米管作为偶极子在交变电场的作用下,产生极化电流,电磁波的能量转换为其他形式的能量,瑞利散射效应和界面极化也是含碳纳米管微波吸收材料的主要吸波机理.     

炭纤维预制体的微波加热性能及其加热机理探讨

通过研究微波功率、炭纤维预制体的密度和叠层层数对预制体微波加热效果的影响, 分析了微波电场在预制体中的分布特点, 提出了炭纤维预制体的微波加热模型, 并对其损耗机制进行了探讨. 结果表明: 在(2450±50)MHz的微波波段, 炭纤维预制体能吸收微波而加热, 其损耗机制主要为偶极子极化、界面极化及电导损耗.     

微波高温加热技术进展

微波高温加热技术被认为是本世纪最有可能取代传统外部加热技术而应用于材料制备的先进技术之一.总结了近年来微波高温加热技术在理论与模拟、结构材料和功能材料方面的研究进展,并对微波高温技术在产业化方面的应用现状和发展前景进行了论述.     

碳纳米管/三元乙丙橡胶复合材料吸波性能的研究

考察了碳纳米管的介电常数,磁导率以及碳纳米管/三元乙丙橡胶复合材料的电磁吸波性能.研究结果表明,碳纳米管介电常数值远大于磁导率值,且电损耗远大于磁损耗,说明碳纳米管是一种电损耗型吸波介质.通过弓形法测定了碳纳米管/三元乙丙橡胶复合材料在2～18GHz范围内的电磁波吸收性能,结果表明,复合材料在5～18GHz范围内具有较好的微波吸收性能.     

The Application of Carbon Nanotube/Graphene‐Based Nanomaterials in Wastewater Treatment

The treatment of organic wastewater is of great significance. Carbon nanotube (CNT)/graphene‐based nanomaterials have great potential as absorbent materials for organic wastewater treatment owing to their high specific surface area, mesoporous structure, tunable surface properties, and high chemical stability; these attributes allow them to endure harsh wastewater conditions, such as acidic, basic, and salty conditions at high concentrations or at high temperatures. Although a substantial amount of work has been reported on the performance of CNT/graphene‐based nanomaterials in organic wastewater systems, engineering challenges still exist for their practical application. Herein, the adsorption mechanism of CNT‐ and graphene‐based nanomaterials is summarized, including the adsorption mechanism of CNTs and graphene at the atomic and molecular levels, their hydrophilic and hydrophobic surface properties, and the structure–property relationship required for adsorption to occur. Second, the structural modification and recombination methods of CNT‐ and graphene‐based adsorbents for various organic wastewater systems are introduced. Third, the engineering challenges, including the molding of macroscopically stable adsorbents, adsorption isotherm models and adsorption kinetic behaviors, and reversible adsorption performance compared to that of activated carbon (AC) are discussed. Finally, cost issues are discussed in light of scalable and practical application of these materials.     

微波辐照液相法合成石墨烯

以天然鳞片石墨为原料, 采用Hummers法先制备出石墨氧化物, 再采用微波辐照法在N-甲基吡咯烷酮(NMP)溶剂中合成出石墨烯. 微波辐照选择性地加热NMP溶剂, 同时石墨氧化物因其含氧官能团分解成CO、CO₂、H₂O气体而得以剥离和还原. 通过XRD、SEM、EDS、TEM、HRTEM、SAED、XPS和Raman测试手段对所合成的石墨烯进行了表征. 结果表明, 所合成的石墨烯尺寸为几微米, 呈透明绢丝状结构, 每个石墨烯片含有2~5层石墨层; 所合成的石墨烯可以均匀地分散在NMP溶剂中.     

Synthesis of a Pillared Graphene Nanostructure: A Counterpart of Three‐Dimensional Carbon Architectures

Graphene is a single sheet of carbon atoms with outstanding electrical and physical properties and is being exploited for applications in electronics, sensors, photovoltaics, and energy storage. A novel 3D architecture called a pillared graphene nanostructure (PGN) is a combination of two allotropes of carbon, including graphene and carbon nanotubes. A one‐step chemical vapor deposition process for large‐area PGN fabrication via a combination of surface catalysis and in situ vapor–liquid–solid mechanisms is described. A process by which PGN layers can be transferred onto arbitrary substrates while keeping the 3D architecture intact is also described. Single and multilayer stacked PGNs are envisioned for future ultralarge and tunable surface‐area applications in hydrogen storage and supercapacitors.     

微波水热法合成钛酸钠盐纳米管

采用微波水热法合成了钛酸钠盐纳米管,考察了原料、反应时间、NaOH浓度等主要影响因素.在微波功率195W、NaOH浓度8—12mol/L、反应时间>70min条件下,得到了形貌均一的钛酸钠盐纳米管,并用TEM、XRD、BET、EDAX和N₂吸附/脱附等对产物进行了表征.研究表明,微波法制得的纳米管合成时间短、热稳定性高,其管壁塌陷温度高于500℃,比普通水热法合成的高100℃左右;所得样品在300℃以上煅烧,可转化为单晶钛酸纳盐纳米管.     

Recycling Polyethylene into High-Value Porous Carbon Composites for Microwave Absorption

The recycling of solid plastic waste has been a major challenge to the sustainable development of today's society. Herein, one of the commonly wasted plastic raw materials, linear low-density polyethylene (LLDPE), is used as the carbon source to explore high-value porous carbon composites for microwave absorption applications. The carbon composites are simply obtained through the delicate carbonization of LLDPE, followed by in situ introducing Ni nanoparticles (NPs) into the carbon monolith. The porous carbon composites show a minimum reflection loss (RL_min) value of −52.2 dB at 1.65 mm, which demonstrates excellent microwave absorption properties of the wasted plastic-derived carbon materials. In addition, the anticorrosion performance of the carbon composites is evaluated by electrochemical technique. Above all, the current study provides a new idea and simple strategy for processing wasted plastics to high-value porous carbon materials.     

定向/有序碳纳米管制备的研究进展

综述了国内外有序、定向碳纳米管制备的研究进展。着重介绍了模板法和等离子体增强化学气相沉积技术在碳纳米管制备方面的应用，并就制备原理、影响因素等作了简单介绍。     

Electronic Property Modification of Single‐Walled Carbon Nanotubes by Encapsulation of Sulfur‐Terminated Graphene Nanoribbons

The use of carbon nanotubes (CNTs) as cylindrical reactor vessels has become a viable means for synthesizing graphene nanoribbons (GNRs). While previous studies demonstrated that the size and edge structure of the as‐produced GNRs are strongly dependent on the diameter of the tubes and the nature of the precursor, the atomic interactions between GNRs and surrounding CNTs and their effect on the electronic properties of the overall system are not well understood. Here, it is shown that the functional terminations of the GNR edges can have a strong influence on the electronic structure of the system. Analysis of SWCNTs before and after the insertion of sulfur‐terminated GNRs suggests a metallization of the majority of semiconducting SWCNTs. This is indicated by changes in the radial breathing modes and the D and G band Raman features, as well as UV–vis–NIR absorption spectra. The variation in resonance conditions of the nanotubes following GNR insertion make direct (n,m) assignment by Raman spectroscopy difficult. Thus, density functional theory calculations of representative GNR/SWCNT systems are performed. The results confirm significant changes in the band structure, including the development of a metallic state in the semiconducting SWCNTs due to sulfur/tube interactions. The GNR‐induced metallization of semiconducting SWCNTs may offer a means of controlling the electronic properties of bulk CNT samples and eliminate the need for a physical separation of semiconducting and metallic tubes.     

碳纳米管构成的二维和三维碳纳米材料的研究进展

碳纳米管(CNTs)可以构成水平排列、垂直排列膜以及多种三维结构碳纳米材料.介绍了 CNTs构成的二维和三维碳纳米材料的分类,综述了其制备方法和应用的研究进展,探讨了该研究领域需要解决的问题以及今后可能的发展前景.     

催化裂解天然气于碳毡内低成本合成碳纳米管

基于制备碳/碳(C/C)复合材料的等温化学气相渗透(ICVI)技术,在1010～1100℃用Fe催化裂解工业天然气可在碳毡内原位合成出碳纳米管(CNTs).扫描电镜(SEM)观察结果表明,1060℃合成的CNTs具有较好的覆盖形貌和均匀管径(110～120nm)且纯净度高.高分辨率透射电镜(HRTEM)和Raman光谱测试结果进一步表明,该温度下合成的CNTs结晶度高,与碳纤维间结合力强.     

薄壁碳纳米管的制取

采用催化裂解法,以二氯苯为碳源,二茂铁为催化剂,制取了薄壁碳纳米管.引入多壁碳纳米管的薄壁指数?来表征多壁碳纳米管的薄壁程度.研究了氢气流量、反应温度和催化剂浓度对薄壁碳纳米管制取的影响.确定了制取薄壁碳纳米管的优化参数:反应温度为850℃,催化剂浓度为0.06g/ml,氩气流量为500ml/min,氢气流量为200ml/min,反应溶液进给量为0.012ml/min.制备出薄壁指数达5.6的大中空薄壁碳纳米管.     

碳纳米管合成进展

自碳纳米管发现以来,其独特的结构与性能以及潜在的应用前景受到广泛的关注.已发展了多种合成技术.从原料、催化、工艺条件、产物形态等方面对重要的合成技术进行了系统的评述,介绍了国内外合成方面的研究现状和面临的挑战,同时提出了一些关于大量有效合成碳纳米管的建议.     

微波法煤基活性炭的制备及其电化学性能研究

以内蒙古优质褐煤为原料,KOH为活化剂,采用微波加热活化法制备超级电容器用活性炭,利用低温氮气吸附及恒流充放电、循环伏安等方法测定活性炭的孔结构及其用作电极材料的电化学性能,并与日本商业化超级电容器用活性炭在结构及性能方面进行对比分析。结果表明,在碱炭比为3,微波活化时间为20min的条件下,可制备出比表面积达2593m2/g、总孔容达1.685cm3/g、孔径主要分布在0.5～10nm之间、中孔率达67.3%、平均孔径为2.61nm的优质活性炭。该活性炭用作超级电容器电极材料在3mol/L KOH电解液中具有优异的电化学性能,电流密度由50mA/g提高到10A/g时,其比电容由346F/g降低到273F/g,显示出良好的功率特性,经1000次循环后,比电容保持率为93.2%。与商业活性炭相比,微波法活性炭的性能更加优良。     

碳负载尺寸可控的铂纳米粒子微波合成和表征

分别以XC-72碳和碳纳米管为载体,H₂PtCl₆为前驱体,用微波辐射加热的方法合成了碳负载的铂纳米粒子,并对其进行了EDX、TEM和XRD表征.研究了H₂PtCl₆乙二醇溶液的pH值对微波合成铂纳米粒子的大小、均匀性及其在碳载体上分散程度的影响.研究结果发现对于Pt/XC-72碳,随着pH值从3.4增加到9.5,铂纳米粒子的平均粒径从5.5nm减小到2.7nm;对于Pt/CNTs,随着pH值从3.5增加到9.4,铂纳米粒子的平均粒径从5.3nm减小到2.8nm.另外,随着pH值的增加,铂纳米粒子的尺寸均匀性及其在碳载体表面的分散程度得到改善.