Solar cells with graphene and carbon nanotubes on silicon

Graphene and carbon nanotubes (CNTs) represent attractive materials for photovoltaic (PV) devices due to their unique electronic and optical properties. Graphene and single-wall carbon nanotubes (SWNTs) layers can be directly configured as energy conversion materials to fabricate thin-film solar cells, serving as both photogeneration sites and charge carrier collecting/transport layers. SWNTs can be modified into either p-type conductor through chemical doping (like acidic purification) or n-type conductor through polymer functionalisation. The solar cells can be simply made of a semitransparent thin film of graphene (or SWNTs) deposited on a proper type of silicon substrate to create high-density Schottky (or p–n) junctions at the interface. The high aspect ratios and large surface area of these carbon nano-structured materials can benefit exciton dissociation and charge carrier transport thus improving the power conversion efficiency.     

碳纳米管的剪切研究

将碳纳米管放入浓硫酸和浓硝酸(3∶1)的混合溶液中,通过长时间超声处理剪切碳纳米管,TEM观测确认,碳纳米管被剪断,长度由1μm以上减小到300nm以下。     

Hybrid metal-based carbon nanotubes: Novel platform for multifunctional applications

Combining objects with diverse properties has often the advantage of giving rise to novel functionalities. In this scenario, metal-filled and decorated carbon nanotubes (m-CNTs) represent a class of hybrid carbon-based nanostructured materials with enormous interest for application in several fields, ranging from nanoelectronics and spintronics to nanomedicine and magnetic data recording. The present review will provide the reader with an overview of state-of-the-art hybrid architectures based on m-CNT systems, methods currently employed for their fabrication, the set of their unique properties and how they can be applied toward novel devices with multifunctional properties for a broad range of applications.     

Effects of amino group on the properties of carbon nanotubes

The surfaces of multi-walled carbon nanotubes were grafted with amino functional groups by reacting acyl-chloride-functionalized carbon nanotubes (CNTs) with hexamethylene diamine, which improves the surfactivity of CNTs. The dispersity, surface morphology, and thermogravimetry of acid-treated and amino-functionalized CNTs were investigated. Amino-functionalized CNTs were added into epoxy resin to analyze the effects of amino functional groups on the properties of resin composites. It was found that the properties of CNTs, such as morphology and scale, were not affected by amino functional groups, but the dispersity in water was highly improved. Amino-functionalized CNTs are better dispersed in resin matrix, and the mechanical properties of composites are improved significantly, whereas the conductivity of composites is not enhanced as expected.     

反应温度对碳纳米管的影响

本文利用化学气相沉积( CVD)法,以乙烯为碳源气体,二茂铁为催化剂,在二氧化硅上制备出一系列碳纳米管,并通过拉曼光谱和扫描电子显微镜( SEM)对其形貌、结构和组分进行表征,分析反应温度对碳纳米管的影响.研究发现:当反应温度为860℃时,有均匀的碳纳米管薄膜生成,其管径和长度分别达到104 nm和95 μm,同时结构缺陷少,非碳管杂质较少,纯度较高.     

碳纳米管对中间相炭微球制备的影响

以中温煤沥青和碳纳米管为原料进行热缩聚反应,制备出含有碳纳米管的中间相炭微球,采用扫描电子显微镜(SEM)、激光粒度仪和X射线衍射(XRD)等分析手段对其形貌及结构进行了表征。研究了添加碳纳米管对中间相炭微球形貌、粒径、产率、微晶结构及热缩聚工艺的影响。结果表明添加碳纳米管能够促进小球成核,阻止小球的融并长大,使炭微球的粒径减小,分布均匀,但过多的碳纳米管会导致球形度变差及中间相沥青产率的降低;碳纳米管的存在使石墨片层尺寸减小,石墨化程度降低;碳纳米管经过酸煮处理后,可以获得球形度更好、含有更大比例碳纳米管的中间相炭微球。     

基于碳纳米管复合物的电化学生物传感器研究进展

新型碳纳米管复合物的开发及其在电化学生物传感器中的应用是近年来材料学和分析领域的研究热点.介绍了碳纳米管复合物在电化学生物传感领域的研究发展,重点对碳纳米管与纳米颗粒、聚合物及离子液体复合材料在电化学生物传感中的应用进行了论述.     

碳纳米管的制备和吸附特性研究

采用CVD法制备了碳纳米管,并用TEM、BET吸附和~(129)Xe NMR对碳纳米管的表面和内部结构进行了表征.通过BET吸附和~(129)Xe NMR的结果对比分析,可以推断碳纳米管并非全部是中空的,而是被许多隔膜分隔成多个锥帽形空腔,这些隔膜一般为无定形碳,五元环或七元环.经过纯化后的碳纳米管具有优异的吸附性能,有望作为新一代的储氢材料.     

碳纳米管增强陶瓷基复合材料研究进展

从制备方法和力学性能两方面出发,综述了碳纳米管增强陶瓷基复合材料的研究现状,针对研究中存在的问题,提出了相应的解决方法,并预测了其发展趋势.     

纳米碳材料在聚合物阻燃中的应用研究进展

综述了近年来纳米碳材料在聚合物阻燃应用方面所取得的研究进展,重点讨论了碳纳米管、富勒烯、石墨烯和纳米炭黑等纳米碳材料在单独用作阻燃剂、改性后用作阻燃剂以及与其他物质协同阻燃聚合物方面取得的研究成果,并指出聚合物/纳米碳材料阻燃体系的研究应侧重于阻燃机理,并将纳米碳材料与其他阻燃剂协同使用,以便发挥各自的优势。     

Selective adsorption of cations on single-walled carbon nanotubes: A density functional theory study

The selective adsorption of cation on single-walled carbon nanotubes (SWNTs) is systemically studied by using density functional theory calculations. It is found that the adsorption energy of cations on SWNTs depends on the concentration of cations and the diameter and the electronic structure of SWNTs. The binding strength of on each SWNT increases monotonically as the concentration of decreases, undergoing a change from endothermic to exothermic reaction. Generally speaking, the binding of on SWNTs becomes weaker as the diameter increases. In the medium-diameter region (9 < d < 11 Å), prefers to interact with metallic SWNTs (m-SWNTs) rather than semiconducting SWNTs (s-SWNTs) at the same concentration of . In the small-diameter region (d < 9 Å), the binding of is nearly independent of metallicity, but it is stronger than that of on the medium-diameter s-SWNTs. In the large-diameter region (d > 11 Å), the dependence of adsorption on the electronic structure is complicated, but the binding of is weaker than that on the medium-diameter s-SWNTs. Our results are in agreement with the experimental report that the small-diameter m- and s-SWNTs and the medium-diameter m-SWNTs are etched away by while the medium-diameter s-SWNTs and the large-diameter m- and s-SWNTs are intact.     

Effect of patterned and aligned carbon nanotubes on field emission properties

The field emission (FE) properties of carbon nanotubes (CNTs) films with different morphologies were simulated and examined. Based on the FE mechanism of aligned CNTs’ emitter the theoretical analysis exhibited the following relations: the FE enhancement factor with the distance between the emitters, the electric field with work function, and the work function with FE enhancement factor. Using the structure-induced CNTs growing method and theoretical results the direction of aligned CNTs could be controlled and the special morphology with different aligned CNTs’ film could be fabricated. Comparing to the experimental results (the medium density and patterned CNTs’ emitters) with the theoretically calculating results the I-V curves had the same trend with only 0.05 mA deviation. Based on the better experimental methods and means the accurate of formula could be further improved by modified the FE properties (Φ, β).     

Fabrication of PtNi bimetallic nanoparticles supported on multi-walled carbon nanotubes

Platinum/nickel bimetallic nanoparticles supported on multi-walled carbon nanotubes (xPtNi/CNTs) were synthesised. The fabrication process includes the chemical modification on the graphene surface of CNTs by acid treatment and the subsequent deposition of Pt or PtNi bimetallic nanoparticles with different compositions of Pt (x = 100, 90, 80 and 70 wt%). The deposition was carried out using ethylene glycol as a reducing agent in the polyol method or using poly(amidoamine) dendrimer as a platform and sodium borohydride as a reducing agent to load the metal nanoparticles on the CNT surface. The structures of the produced PtNi/CNT nanoparticles were investigated by ultraviolet absorption spectra, X-ray diffraction (XRD) and the composite ratio consisting of 70 wt% of metal content and 30 wt% of CNTs was confirmed by the thermogravimetric analysis. The morphology and the phase identification of the produced PtNi/CNT nanoparticles were investigated by high-resolution scanning electron microscope, transmission electron microscope and XRD measurements. It was observed that the deposited Pt and PtNi bimetallic nanoparticles on the surface of CNTs had average particle sizes of 2–16 nm, when they were prepared from the polyol method. On the other hand, the PtNi/CNT nanoparticles prepared by using a dendrimer as an intermediate had a smaller particle size and more uniform size distribution of the quantum dot size ranged from 2 to 4 nm.     

单壁碳纳米管束的排布

流体排布法是实现碳纳米管定向排列的一种简单的方法。采用流体排布法在具有浸润性图案化的基底上成功地对单壁碳纳米管(SWNTs)束进行了水平方向上的排布。将SWNTs悬浮液滴入光刻胶制成的微通道中,在流体剪切力作用下,弯曲的SWNTs在一定程度上会被拉伸并且平行地排列在纳米级宽度的微通道中。将排列好的SWNTs阵列转移到一些不同间距的金电极对上面,制作成碳纳米管场效应晶体管(CNTFET)。CNTFET的电性能测试结果表明,制备的SWNTs束可以制造出不同电极间距同时具有良好电性能的CNTFET。     

利用碳纳米管吸附溶液中金属离子的研究进展

碳纳米管具有中空层状结构,大的比表面积和长径比,高的化学稳定性和热稳定性以及端帽、内腔、管壁容易被修饰等特点,是一种较为理想的吸附材料。综述了碳纳米管与吸附相关的结构和性质,分析了经硝酸氧化处理过的碳纳米管对溶液中金属离子的吸附作用原理,以及pH值、离子浓度对吸附作用的影响。讨论了将碳纳米管对金属离子的吸附作用与分离富集技术相联系,应用于元素分析测定,能够提高方法灵敏度,降低了元素检出限。在仪器分析方面将有巨大潜力。     

Comparative experimental study of methane adsorption on multi-walled carbon nanotubes and granular activated carbons

In this study, methane storage capacity of granular activated carbons (GACs) and two types of multi-walled carbon nanotubes (MWCNTs) was investigated and compared. An experimental apparatus consisting a dual adsorption vessel was set up for measurement of equilibrium adsorption of methane on adsorbents using volumetric technique at pressure range of 0–50?bar at different temperatures. The first type of MWCNs has shown lower methane uptake (4.5?mmol?g^?1) compared to GACs (6.5?mmol?g^?1) at the temperature of 283.15?K and the pressure of 50?bar, while 33?mmol?g^?1 of methane storage capacity was achieved using the second type of MWCNTs that is much higher than methane storage on GACs at the same operating conditions. The superior uptake performance for the second type of MWCNTs can be attributed to its specific characteristics such as smaller pore size and higher pore volume. The experimental data of adsorption were almost equally well described by Langmuir, Freundlich and Sips equations to determine the model isotherms. The isosteric heat of methane adsorption on the adsorbent was calculated based on Clausius–Clapeyron and the Sips isotherm model using the experimental data at different temperatures. Results revealed that the isosteric heat of methane adsorption on MWCNTs was lower than the heat of methane adsorption on GACs. Low values obtained for isosteric heats of adsorption indicated dominance of physisorption mechanism for all adsorbents. In general, the obtained data indicated that some well-structured MWCNTs with uniform and narrow size distribution as well as higher pore volume are potential materials for methane storage and deserve further study.     

纳米碳管/羟基磷灰石复合材料的凝胶注模

采用凝胶浇注成型工艺制备了纳米碳管/ 羟基磷灰石复合材料坯体。研究了p H 值、分散剂、固相含量(纳米碳管和羟基磷灰石在料浆中的质量分数) 、分散工艺等因素对料浆和复合材料坯体性能的影响, 对坯体的力学性能进行了测试, 借助扫描电镜分析了坯体的微观组织。实验发现, 料浆的p H 值应控制在10～12 的范围内;聚甲基丙烯酸铵的浓度为0. 6 %时, 羟基磷灰石悬浮体流动性最好; 十二烷基磺酸钠的浓度在SDS/ CNTs = 1 %～2 %时, 纳米碳管/ 羟基磷灰石复相料浆的粘度最低; 采用球磨法制备的复相料浆固相含量达到55 % , 复合材料坯体的抗弯强度达到57. 403 MPa 。      

基于碳纳米管的纳米泵浦系统模拟研究

碳纳米管的纳米泵浦效应在药物传输、新型纳米推进器与传感器等方面有着广泛的潜在应用,而纳米泵浦效应能够获得应用的前提是建立稳定的纳米泵浦系统。通过分子动力学模拟,研究了基于碳纳米管的稳定纳米泵浦系统的建立方法和影响纳米泵浦效应的关键因素＂泵浦系统的边界势垒＂;在建立稳定泵浦系统和克服边界势垒的条件下,模拟了在外界驱动下的纳米泵浦过程。该项研究的结果为碳纳米管纳米泵浦效应的应用提供了重要理论参考。     

Highly conductive polymer materials based multi-walled carbon nanotubes as counter electrodes for dye-sensitized solar cells

Poly(3,4-ethylenedioxxythiophene) (PEDOT), polyaniline (PANI) and polythiophene (PTh) based multi-walled carbon nanotube (MWCNT) composites were successfully prepared using RF-rotating plasma grafting method. Morphological characterizations of composites were determined using scanning electron microscopy (SEM), which showed that conducting polymers (CPs) of PEDOT, PANI and PTh were coated on the surface of CNTs. The surface properties of the Carbon Nanotube (CNT) composites were also determined by using Infrared Spectra (FT-IR), X-ray Photon Spectra (XPS), and Scanning Electron Microscopy-Energy Dispersive X-ray Spectra (SEM-EDX) analysis. X-ray photon spectra results confirmed the formation of the composites. Composites of MWCNT were used in dye-sensitized solar cells (DSSCs) as counter electrodes and exhibited short-circuit photocurrent densities of 11.19, 10.70 and 8.54 mA/cm² for PANI/MWCNT, PTh/MWCNT and PEDOT/CNT, respectively.     

环己烷浮游催化法在碳纤维表面生长碳纳米管

以环己烷为碳源、二茂铁为催化剂前躯,采用浮游催化法成功的在碳纤维表面生长了碳纳米管(CNT),制备了多尺度杂化材料CNTs/CF。实验重点考察了反应温度、二茂铁浓度、载气等参数对CNT在纤维表面生长的影响,通过扫描电镜(SEM)、投射电镜(TEM)研究了CNTs/CF的形貌及产物CNT的微观结构。当固定反应温度为820℃、二茂铁-环己烷浓度为2g/100mL时,随着氢气在载气中含量在0～100%范围内变化,产物CNT直径亦有86nm降低至39nm。通过单丝拉伸测试发现,相比初始碳纤维,不同长度的CNTs/CF单纤维强度下降幅度均在10%以内。