Synthesis of carbon nanotube arrays using ethanol in porous anodic aluminum oxide template

Carbon nanotube (CNT) arrays confined by porous anodic aluminum oxide (AAO) template were synthesized using ethanol as reactant carbon source at low pressure. Images by scanning electron microscope (SEM) and low magnification transmission electron microscopy (TEM) show that these CNTs have highly uniform outer diameter and length, absolutely controlled by the diameter and depth of nano-channel arrays of the AAO. High resolution transmission electron microscopy (HRTEM) imaging indicates that the graphitization of the CNT walls is better than the results reported on this kind of template-based CNT arrays, although it is not so good as that of multiwalled carbon nanotubes (MWCNTs) synthesized by catalysis. CNTs synthesized using acetylene as reactant gas show much less graphitization than those prepared using ethanol by comparing the results of HRTEM and Raman spectroscopy. The etchingeffects of decomposed OH radicals on the amorphous carbon and the roughness of AAO nano-channel arrays on the CNTs growth were employed to explain the graphitization and growth of the CNTs.     

The template preparation and characterization of three new shapes of titania nanometer-array systems

Nano-structure systems such as nano-structure de- vices and quantum devices have become a hot spot[1] in the materials science. Recently, the synthesis and the preliminary exploration of the properties of novel nano-structures or nanometer constitutional …     

羟基磷灰石纳米线的可控制备

用P2O5和Ca(NO3)2作为前驱体溶液，将溶胶—凝胶法与氧化铝模板(AAO)技术相结合，大面积制备出结构均匀、晶相一致、彼此平行且高度有序的羟基磷灰石(HAP)纳米线．结果表明，通过控制制备AAO模板的条件，可达到控制HAP形貌的目的．     

Synthesis of carbon nanotube array using corona discharge plasma-enhanced chemical vapor deposition

A corona discharge phasma-enhanced chemical vapor deposition with the features of atmospheric pressure and low temperature has been developed to synthesize the carbon nanotube array ,The array was synthesized from methane and hydrogen mixture in anodic aluminum oxide template channels in that cobalt was electrodeposited at the bottom.The characterization results by the scanning electron microscopy,transmission electron microscopy,energy dispersive X-ray spectroscopy and Raman spectroscopy indicate that the array consists of carbon nanotubes with the diameter of about 40 nm and the length of more than 4 μm, and the carbon anotubes are mainly restrained within the channels of templates.     

掺氮碳纳米管阵列的制备及其场发射特性

使用结构简单的单温炉设备,以二茂铁为碳源与催化剂,三聚氰胺为氮源在硅基底制备出了碳纳米管阵列。所得的碳纳米管为多壁结构,单根碳纳米管的平均直径为50nm,长度为15μm,有着很好的定向性。透射电子显微镜(TEM)和X射线光电子谱(XPS)分析表明所得的碳纳米管是氮掺杂的。利用场发射显微镜研究了掺氮碳纳米管阵列的平面场发射特性,相应的开启场强为1.60V/μm,场发射图像表明了其有较高的场发射点密度。     

细胞色素C在纳米银线阵列传感器上的电化学研究

在自制的多孔阳极氧化铝模板辅助下,用直流电解法在玻碳电极表面成功生长了大面积的纳米银线阵列。高分辨扫描电镜照片显示,银纳米线阵列均匀有序,单根纳米线的直径约40 nm,这与所用氧化铝模板的平均孔径(40 nm)相当吻合。将银纳米线阵列传感器用于细胞色素C的电化学研究,灵敏度大大提高,检测限达到0.1 mg/mL。     

High reproducibility and sensitivity of bifacial copper nanowire array for detection of glucose

The ordered bifacial copper nanowire array (Cu BNWA) was synthesized by a template assisted electrochemical deposition method. The morphology and structure of the as-prepared samples were investigated by field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD). The results show that the ordered Cu nanowire array with uniform geometrical dimensions covered both side of the Cu substrate. When used as the electrode for glucose detection, the minimum detectable concentration of glucose can be reached as low as 0.2 mM. Impressively, the sample still showed high sensitivity and stability for glucose detection after two months placement in ambient environment. These excellent performances of the Cu BNWA make it a promising non-enzyme glucose detection sensor for various applications.     

Growth of graphite film over the tops of vertical carbon nanotubes using Ni/Ti/Si substrate

A substrate with Ni/Ti/Si structure was used to grow vertical carbon nanotubes (CNTs) with a graphite fihn over CNT tops by thermal chemical vapor deposition with CH₄ gas as carbon source. The carbon nanotubes and the substrate were characterized by a field emission scanning electron microscope for the morphologies, a transmission electron microscope for the microstructures, a Raman spectrograph for the ctystallinity, and an Auger electron spectrometer for the depth distribution of elements. The result shows that when the thickness ratio of Ni layer to Ti layer in substrate is about 1, a graphite film with relatively good quality can be formed on the CNT tops.     

Carbon nanotubes prepared by anodic aluminum oxide template method

One of the most unique structural characteristics of carbon nanotubes (CNTs) differentiating from other carbon materials is their hollow nanochannles, which can be utilized for encapsulating and loading foreign matters. The anodic aluminum oxide (AAO) template technique enables the diameter, length, and cap structure control of the replicated CNTs, and thus shows advantages in pore structure control over the traditional CNT growth approaches. This review details the synthesis of CNTs with tunable diameter, length, wall thickness, and crystalline by using the AAO template method. The doping of heteroatoms and filling of foreign matters into AAO-CNTs are also addressed. Moreover, the main challenges and developing trends of the AAO template method are discussed.     

Synthesis of carbon nanotube array using corona discharge plasma-enhanced chemical vapor deposition

Carbon nanotube array plays an important role in the area of nanomaterials due to its potential applications, e.g. as field emitter in flat panel display[1,2] and as template for synthesizing arrays of other important nanomaterials[3]. Anodic aluminum oxide (AAO) template possesses an ordered porous structure that is formed through self-or- ganization during anodization[4,5], and is widely used to synthesize one-dimensional nanomaterial arrays[6]. Carbon nanotubes are usually assembled into t…     

阳极氧化处理的铝为模板电化学沉积铜纳米线

研究如何去除阳极氧化铝膜(AAO)纳米孔与铝基之间的阻挡层。介绍了一种氧化铝模板经阶梯降流处理后可以有效去除AAO模板阻挡层的新方法,并以带铝基的氧化铝膜为模板直流电化学沉积制备了线径可控、大小均一的晶态铜纳米线。     

Analytical optimization for field emission of carbon nanotube array

To optimize field emission （FE） property of carbon nanotube （CNT） array on a planar cathode surface, the Fowler-Nordheim formula has been used to discuss the maximum of the emission current density with the floating sphere model in this paper. The emission current density is dominating as the analytical Fowler-Nordheim function of the intertube distance, and the maximum of the emission current density is deduced and discussed. The results indicate that the intertube distance in CNT array critically affects the field enhancement factor and the emission current density, whose maximum occurs at the intertube distance approximating a tenth of the tube height. Considering the emission current density and the field enhancement factor, the FE can be optimized analytically when the intertube distance is about a tenth of the tube height.     

Optimizing the fabrication of carbon nanotube electrode for effective capacitive deionization via electrophoretic deposition strategy

In order to obtain superior electrode performances in capacitive deionization(CDI), the electrophoretic deposition(EPD) was introduced as a novel strategy for the fabrication of carbon nanotube(CNT) electrode.Preparation parameters, including the concentration of slurry components, deposition time and electric field intensity, were mainly investigated and optimized in terms of electrochemical characteristic and desalination performance of the deposited CNT electrode. The SEM image shows that the CNT material was deposited homogeneously on the current collector and a non-crack surface of the electrode was obtained. An optimal preparation condition of the deposited CNT electrode was obtained and specified as the Al(NO3)3 M concentration of 1.3 × 10~(-2) mol/L, the deposition time of 30 min and the electric field intensity of 15 V/cm. The obtained electrode performs an increasing specific mass capacitance of 33.36 F/g and specific adsorption capacity of 23.93 mg/g, which are 1.62 and 1.85 times those of the coated electrode respectively. The good performance of the deposited CNT electrode indicates the promising application of the EPD methodology in subsequent research and fabrication of the CDI electrodes for CDI process.     

Simple method to rapidly fabricate chain-like carbon nanotube films and its field emission properties

A simple process to fabricate chain-like carbon nanotube (CNT) films by microwave plasma-enhanced chemical vapor deposition (MPCVD) was developed successfully. Prior to deposition, the Ti/Al₂O₃ substrates were ground with Fe-doped SiO₂ powder. The nano-structure of the deposited films was analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. The field electron emission characteristics of the chain-like carbon nanotube films were measured under the vacuum of 10-5 Pa. The low turn-on field of 0.80 V/μm and the emission current density of 8.5 mA/cm2 at the electric field of 3.0 V/μm are obtained. Based on the above results, chain-like carbon nanotube films probably have important applications in cold cathode materials and electrode materials.     

Ohmic contact properties of p-type surface conductive layer on H-terminated diamond films prepared by DC arc jet CVD

With the advantages of high deposition rate and large deposition area, polycrystalline diamond films prepared by direct current (DC) arc jet chemical vapor deposition (CVD) are considered to be one of the most promising materials for high-frequency and high-power electronic devices. In this paper, high-quality self-standing polycrystalline diamond films with the diameter of 100 mm were prepared by DC arc jet CVD, and then, the p-type surface conductive layer with the sheet carrier density of 1011-1013 cm?2 on the H-terminated diamond film was obtained by micro-wave hydrogen plasma treatment for 40 min. Ti/Au and Au films were deposited on the H-terminated diamond surface as the ohmic contact electrode, respectively, afterwards, they were treated by rapid vacuum annealing at different temperatures. The properties of these two types of ohmic contacts were investigated by measuring the specific contact resistance using the transmission line method (TLM). Due to the formation of Ti-related carbide at high temperature, the specific contact resistance of Ti/Au contact gradually decreases to 9.95 × 10?5 Ω·cm2 as the temperature increases to 820℃. However, when the annealing temperature reaches 850℃, the ohmic contact for Ti/Au is degraded significantly due to the strong diffusion and reaction between Ti and Au. As for the as-deposited Au contact, it shows an ohmic contact. After annealing treatment at 550℃, low specific contact resistance was detected for Au contact, which is derived from the enhancement of interdiffusion between Au and diamond films.     

Janus few layered graphene with asymmetric wettability as anti-flooding cathode supports in proton exchange membrane fuel cells

Water balance in cathode catalyst layer (CCL) is crucial for proton exchange membrane fuel cells (PEMFCs). Herein, we report a novel strategy to develop a Janus few layered graphene particles (FLGP) with asymmetric wettability by varying the carbon precursors in the chemical vapor deposition (CVD) process. Using the Janus FLGP supported Pt with asymmetric wettability as the cathode of a PEMFC, a peak power density of 632 mW cm⁻² was achieved, which was about two-folds of the hydrophobic FLGP and three-folds of hydrophilic FLGP based cathode, respectively. The enhanced performance could be ascribed to the well-constructed three-phase boundary in an anti-flooding cathode, leading to enlarged electrochemical active surface area and facilitated mass transfer. This work may provide new clues for improving water management in PEMFCs.     

用AAO模板及脉冲激光溅射制备量子点阵

 利用多孔阳极氧化铝(anodic aluminum oxide,AAO)作为模板,采用准分子脉冲激光溅射方法(pulsed laser deposition,PLD)成功制备了光荧光材料La_0.95Eu_0.05BaB₉O₁₆的量子点阵,用扫描电镜表征了AAO模板和制备的量子点阵,测量了靶材和量子点阵的光荧光谱.讨论了用此方法制备的量子点阵的结构和发光特性.证明此方法可为未来制备其它材料的量子点阵开辟了一条途径.     

电化学组装一维纳米线阵列温差电材料

低维温差电材料具有比块状温差电材料更高的优值,因而研制具有纳米线阵列结构的温差电材料对于提高材料的温差电转换效率具有重要意义.以具有纳米孔阵列结构的氧化铝多孔模板为阴极,在含有Bi 3、HTeO2 1的酸性溶液中,采用直流电沉积技术,通过在氧化铝多孔模板的纳米级微孔中沉积铋和碲,实现了一维纳米线阵列铋碲温差电材料的电化学组装.环境扫描电子显微镜(ESEM)和透射电子显微镜(TEM)的分折表明,电化学组装出的铋碲纳米线分布均匀,形状规则.铋碲纳米线的组成可方便地通过调整电沉积电位加以控制.     

High-performance doping-free carbon-nanotube-based CMOS devices and integrated circuits

Ballistic n-type carbon nanotube (CNT)-based field-effect transistors (FETs) have been fabricated by contacting semiconducting single-walled CNTs (SWCNTs) using Sc or Y. The n-type CNT FETs were pushed to their performance limits through further optimizing their gate structure and insulator. The CNT FETs outperformed n-type Si metal-oxide-semiconductor (MOS) FETs with the same gate length and displayed better downscaling behavior than the Si MOS FETs. Together with the demonstration of ballistic p-type CNT FETs using Pd contacts, this technological advance is a step toward the doping-free fabrication of CNT-based ballistic complementary metal-oxide-semiconductor (CMOS) devices and integrated circuits. Taking full advantage of the perfectly symmetric band structure of the semiconductor SWCNT, a perfect SWCNT-based CMOS inverter was demonstrated, which had a voltage gain of over 160. Two adjacent n- and p-type FETs fabricated on the same SWCNT with a self-aligned top-gate realized high field mobility simultaneously for electrons (3000 cm² V^?1 s^?1) and holes (3300 cm² V^?1 s^?1). The CNT FETs also had excellent potential for high-frequency applications, such as a high-performance frequency doubler.     

Fabrication and thermal conductivity of copper matrix composites reinforced by tungsten-coated carbon nanotubes

Carbon nanotubes (CNTs) were coated by tungsten using metal organic chemical vapor deposition. Magnetic stirring was employed to disperse the W-coated CNTs (W-CNTs) in a Cu matrix, and then, the mixed powders were consolidated by spark plasma sintering. The W-CNTs obtained a uniform dispersion within the Cu matrix when the W-CNT content was less than 5.0vol%, but high content of W-CNTs (10vol%) resulted in the presence of clusters. The W-CNT/Cu composites containing low content of W-CNTs (<5.0vol%) exhibited a higher thermal conductivity than the sintered pure Cu, while the CNT/Cu composites exhibited no increase in thermal conductivity after the incorporation of uncoated CNTs. The W-CNT content was found to play a crucial role in determining the thermal conductivity of the W-CNT/Cu composites. The thermal conductivity of the W-CNT/Cu composites increased first and then decreased with the W-CNT content increasing. When the W-CNT content was 2.5vol%, the W-CNT/Cu composite obtained the maximum value of thermal conductivity. The thermal resistance of the (W-CNT)-Cu interface was predicted in terms of Maxwell-Garnett effective medium approximation, and its calculated value was about 3.0×10-9 m2·K·W-1.