滴涂法制备石墨烯/碳纳米管复合薄膜及其表征

以化学气相沉积(CVD)法制备的石墨烯和碳纳米管的邻二氯苯分散液为原料, 采用滴涂法制备石墨烯/碳纳米管复合薄膜, 用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、拉曼光谱(Raman)和X射线光电子能谱(XPS)对其形貌和结构进行表征。实验发现随着碳纳米管分散液浓度的增大, 复合薄膜结构中碳纳米管的面密度线性增大。利用紫外-可见光谱仪和四探针测试仪表征了不同碳纳米管浓度下复合薄膜的透光率及其薄层电阻, 结果表明: 随着碳纳米管浓度的增大, 复合薄膜的透光率及其薄层电阻都将减小, 当碳纳米管浓度为0.1 mg/mL时, 复合薄膜的透光率(550 nm)及其薄层电阻分别为92.18%和0.998 kΩ/□。实验通过调节碳纳米管浓度制备得到不同性能的石墨烯/碳纳米管复合薄膜, 该复合薄膜在透明电极、场效应晶体管和激光锁模等方面具有潜在应用。     

Carbon Nanotube and Graphene‐based Bioinspired Electrochemical Actuators

Bio‐inspired actuation materials, also called artificial muscles, have attracted great attention in recent decades for their potential application in intelligent robots, biomedical devices, and micro‐electro‐mechanical systems. Among them, ionic polymer metal composite (IPMC) actuator has been intensively studied for their impressive high‐strain under low voltage stimulation and air‐working capability. A typical IPMC actuator is composed of one ion‐conductive electrolyte membrane laminated by two electron‐conductive metal electrode membranes, which can bend back and forth due to the electrode expansion and contraction induced by ion motion under alternating applied voltage. As its actuation performance is mainly dominated by electrochemical and electromechanical process of the electrode layer, the electrode material and structure become to be more crucial to higher performance. The recent discovery of one dimensional carbon nanotube and two dimensional graphene has created a revolution in functional nanomaterials. Their unique structures render them intriguing electrical and mechanical properties, which makes them ideal flexible electrode materials for IPMC actuators in stead of conventional metal electrodes. Currently although the detailed effect caused by those carbon nanomaterial electrodes is not very clear, the presented outstanding actuation performance gives us tremendous motivation to meet the challenge in understanding the mechanism and thus developing more advanced actuator materials. Therefore, in this review IPMC actuators prepared with different kinds of carbon nanomaterials based electrodes or electrolytes are addressed. Key parameters which may generate important influence on actuation process are discussed in order to shed light on possible future research and application of the novel carbon nanomateials based bio‐inspired electrochemical actuators.     

High‐Performance Biscrolled MXene/Carbon Nanotube Yarn Supercapacitors

Yarn‐shaped supercapacitors (YSCs) once integrated into fabrics provide promising energy storage solutions to the increasing demand of wearable and portable electronics. In such device format, however, it is a challenge to achieve outstanding electrochemical performance without compromising flexibility. Here, MXene‐based YSCs that exhibit both flexibility and superior energy storage performance by employing a biscrolling approach to create flexible yarns from highly delaminated and pseudocapacitive MXene sheets that are trapped within helical yarn corridors are reported. With specific capacitance and energy and power densities values exceeding those reported for any YSCs, this work illustrates that biscrolled MXene yarns can potentially provide the conformal energy solution for powering electronics beyond just the form factor of flexible YSCs.     

碳纳米管表面沉积氧化镍及其超电容器的电化学行为

通过催化裂解法制备了碳纳米管并进一步制备了碳纳米管薄膜电极.基于该种材料的超电容器电极比容量达到36F/g.研究了在碳纳米管薄膜基体上使用电化学方法沉积氧化镍的新工艺,制备出碳纳米管和氧化镍的复合电极.电化学测试证明复合电极的比容量提高到52F/g以上且基于这种复合电极的超电容器具有极低的自放电率.     

石墨烯/炭气凝胶的制备及其结构与性能研究

以间苯二酚(R)和甲醛(F)为炭前驱体原料, 通过溶胶-凝胶法制备石墨烯/炭气凝胶复合材料。采用XRD、Raman、SEM和N₂吸附/脱附等对样品进行结构表征。结果表明: 石墨烯为R和F的聚合提供形核场所, R和F首先在氧化石墨烯(GO)表面聚合, 随着RF含量的增加, 复合炭气凝胶(RF)结构从石墨烯薄片层为骨架的三维网络, 经RF基炭球包裹于石墨烯的网络结构, 最终转变为球形团簇交联的三维网络。石墨烯/炭气凝胶复合材料的比表面积随着RF的增加先增大后减小。当GO与RF质量比为1︰100时, GO/RF-100用作超级电容器电极材料, 在6 mol/L KOH电解液中的比电容达169 F/g, 具有较好的电容特性。     

Electrochemically Powered,Energy‐Conserving Carbon Nanotube Artificial Muscles

While artificial muscle yarns and fibers are potentially important for many applications, the combination of large strokes, high gravimetric work capacities, short cycle times, and high efficiencies are not realized for these fibers. This paper demonstrates here electrochemically powered carbon nanotube yarn muscles that provide tensile contraction as high as 16.5%, which is 12.7 times higher than previously obtained. These electrochemical muscles can deliver a contractile energy conversion efficiency of 5.4%, which is 4.1 times higher than reported for any organic‐material‐based artificial muscle. All‐solid‐state parallel muscles and braided muscles, which do not require a liquid electrolyte, provide tensile contractions of 11.6% and 5%, respectively. These artificial muscles might eventually be deployed for a host of applications, from robotics to perhaps even implantable medical devices.     

Carbon Nanotube Yarn‐Based Glucose Sensing Artificial Muscle

Boronic acid (BA), known to be a reversible glucose‐sensing material, is conjugated to a nanogel (NG) derived from hyaluronic acid biopolymer and used as a guest material for a carbon multiwalled nanotube (MWNT) yarn. By exploiting the swelling/deswelling of the NG that originates from the internal anionic charge changes resulting from BA binding to glucose, a NG MWNT yarn artificial muscle is obtained that provides reversible torsional actuation that can be used for glucose sensing. This actuator shows a short response time and high sensitivity (in the 5–100 × 10^?3m range) for monitoring changes in glucose concentration in physiological buffer, without using any additional auxiliary substances or an electrical power source. It may be possible to apply the glucose‐sensing MWNT yarn muscles as implantable glucose sensors that automatically release drugs when needed or as an artificial pancreas.     

Oxygen Evolution Assisted Fabrication of Highly Loaded Carbon Nanotube/MnO2 Hybrid Films for High‐Performance Flexible Pseudosupercapacitors

To date, it has been a great challenge to design high‐performance flexible energy storage devices for sufficient loading of redox species in the electrode assemblies, with well‐maintained mechanical robustness and enhanced electron/ionic transport during charge/discharge cycles. An electrochemical activation strategy is demonstrated for the facile regeneration of carbon nanotube (CNT) film prepared via floating catalyst chemical vapor deposition strategy into a flexible, robust, and highly conductive hydrogel‐like film, which is promising as electrode matrix for efficient loading of redox species and the fabrication of high‐performance flexible pseudosupercapacitors. The strong and conductive CNT films can be effectively expanded and activated by electrochemical anodic oxygen evolution reaction, presenting greatly enhanced internal space and surface wettability with well‐maintained strength, flexibility, and conductivity. The as‐formed hydrogel‐like film is quite favorable for electrochemical deposition of manganese dioxide (MnO₂) with loading mass up to 93 wt% and electrode capacitance kept around 300 F g^?1 (areal capacitance of 1.2 F cm^?2). This hybrid film was further used to assemble a flexible symmetric pseudosupercapacitor without using any other current collectors and conductive additives. The assembled flexible supercapacitors exhibited good rate performance, with the areal capacitance of more than 300 mF cm^?2, much superior to other reported MnO₂ based flexible thin‐film supercapacitors.