表面官能团化多壁碳纳米管/环氧树脂复合材料的制备及性能

本文首先将多壁碳纳米管(MWNT)进行表面化学修饰,接入羧基、胺基等官能团,采用红外光谱进行了表征.以纯化后的MWNT和表面化学修饰的MWNT作为填料,制备了MWNT /环氧树脂复合材料,研究了MWNT的加入对环氧树脂的力学性能、电学性能、热稳定性和玻璃化转变温度等的影响,并利用场发射电镜观察了胺基化MWNT在环氧树脂基体中的分散情况.     

TiO2-grafted multi-walled carbon nanotubes for dye-sensitized solar cells

Dye-Sensitized Solar Cells (DSSCs) comprised of TiO2 porous films with multi-walled carbon nanotubes (MWNT) were prepared at low temperature (150 degrees C). MWNT were incorporated to facilitate the fast electron transport resulting from metallic properties of carbon nanotubes. In order to enhance the effect of MWNT incorporation, TiO2-grafted MWNT (TiO2-MWNT) was synthesized which can increase the electron transport rate further due to proximity of TiO2 to MWNT The presence of TiO2 nanoparticles on the surface of MWNT was confirmed by electron microscopy and energy dispersive X-ray spectroscopy. As in the DSSCs prepared through high temperature sintering of photoanodes, the maximum content of MWNT incorporated into TiO2 was limited to 0.01 wt% relative to TiO2. TiO2 photoanodes including TiO2-grafted MWNT (TiO2-MWNT/P25) enhanced the cell efficiencies by ca. 28% and 14%, relative to TiO2 photoanodes without and with MWNT respectively, reaching the efficiency of 5.0%. Electrochemical impedance spectroscopy (EIS) was utilized to examine the effect of incorporation of TiO2 nanoparticles grafted to MWNT on the cell performance.     

熔融纺丝方法制备纳米碳管/聚丙烯复合纤维及其拉伸性能

采用传统的熔融纺丝技术大量制备了定向性良好的纳米碳管／聚丙烯复合纤维。扫描电镜观察证实了纳米碳管在纤维里的定向性以及分散性都得到了较大的改善。通过拉伸实验测试了纳米碳管／聚丙烯复合纤维的力学性能，采用weibull统计分析发现纳米碳管的添加显著提高了复合纤维的拉伸强度，当添加纳米碳管的质量分数达到3％时，纤维强度最高，达到61MPa，超过聚丙烯纤维强度120％。复合纤维拉伸断口的形貌特征也证实了纳米碳管添加对复合纤维拉伸性能影响存在临界现象。     

Multi-walled carbon nanotube/silver nanoparticles used for thermal transportation

A green method was applied to prepare composites of multi-walled carbon nanotubes (MWNTs) decorated with silver nanoparticles (Ag-NPs). MWNTs were functionalized using ball milling technology in the presence of ammonium bicarbonate, and the traditional method of silver mirror was used to decorate MWNTs to obtain Ag/MWNT composite. The obtained Ag/MWNT composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transmission infrared spectroscopy, and Brunauer–Emmet–Teller (BET) surface area analysis. SEM characterization showed that Ag-NPs distributed uniformly on the walls of MWNTs. The content and size of Ag-NPs could be controlled by adjusting the redox time. XRD patterns demonstrated that the Ag-NPs are composed of pure Ag and crystallized well. BET analysis indicated that the specific surface areas of Ag/MWNT decrease with increasing the content of Ag-NPs, and this result is similar to that of the literature. The measurement results of the thermal property showed that the thermal conductivity of the nanofluid containing Ag/MWNT composites was higher than that of nanofluid containing pristine or functionalized MWNTs.     

Study on the infrared property of polyaniline/multi-wall carbon nanotube composite

Composites of polyaniline (PANI) and multi-wall carbon nanotube (MWNT) were synthesized by in situ polymerization with different MWNT content. The composites were characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The SEM photos indicated that a mass of MWNT was enchased into PANI matrix when the content of MWNT was low. With the MWNT content increases, the surface of MWNT was covered with PANI and formed the core-shell structure. From the FT-IR spectroscopy of the composites, it can be confirmed that there was interaction between PANI and multi-wall carbon nanotube. The composites had better thermal stability than pure PANI. Infrared emission property of the composites was analyzed by an IR-II infrared emissivity instrument and an infrared camera. It was found that infrared emission of the composites was lower than pure PANI in all wavelength range and infrared emissivity value was related to the content of MWNT in the composites.     

Process optimization and microstructural analysis of aluminum based composite reinforced by multi‐walled carbon nanotubes with various aspect ratios

The dispersion of carbon nanostructures in metallic matrix with strong bonding is a very important challenge to achieve a composite with high mechanical properties. In this work, the effect of aspect ratio of reinforcement phase, weight percent and using improved mechanical alloying process and sonication on the well dispersion of multiwalled carbon nanostructures (MWCNTs) were investigated. Moreover, the hot pressing conditions were optimized by factorial design technique to achieve the highest relative density. Field emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM) and X‐ray diffraction were used to analyse the microstructure. Also, the particle size of the grain structure of composite containing multi‐walled carbon nanotubes determined for evaluating the influence of aspect ratio on grain growth. The results verified that by using conventional method of alloying, grinding process and agglomeration of 2 wt% multi‐walled carbon nanotubes with long length can be occurred. By decreasing the weight percent of multi‐walled carbon nanotubes to 1 wt%, dispersion process progressed slightly. Short length multi‐walled carbon nanotubes showed more clustering and minor damage in both 1 and 2 wt%. By using modified design of alloying (using magnet), both types of multi‐walled carbon nanotubes dispersed better than conventional design in the matrix with good bonding at initial times.     

碳化铈水解氧化法制备CeO2纳米粉

提出了一种可大规模制备CeO2纳米粉的有效方法.用碳化铈水解氧化制得颗粒大小为3~5 nm的CeO2纳米粉.研究了各种实验参数包括水解温度、反应时间和投料比对CeO2纳米粉比表面积的影响.结果表明:较低的水解温度(室温附近),较高的投料比(1:20(g/mL))和适当的反应时间(18 h)可得到比表面积为149 m2/g的CeO2纳米粉.优化实验参数(水解温度为30℃,水解时间为18 h,投料比为1:20(g/mL),滤饼在空气中80℃烘干4 h)得到中间产物Ce(OH)3和目标产物CeO2,并用XRD、TEM、SAED及紫外可见光分光光度计进行测试表征.发现Ce(OH)3是由大量长为50~100 nm,直径为5~20 nm的纳米棒组成.CeO2纳米粉具有较高的紫外吸收性能和较好的催化CO性能.     

PMDA-ODA型聚酰亚胺炭/碳纳米管杂化膜的制备及气体分离性能研究

针对现有气体分离炭膜存在的渗透速率低等问题, 提出并设计在PMDA-ODA型聚酰亚胺前驱体中掺杂碳纳米管, 经高温热解后制备炭/碳纳米管杂化膜. 分别采用透射电镜(TEM)、X射线衍射分析(XRD)和气体渗透实验对炭/碳纳米管杂化膜的微观结构和分离性能进行表征. 实验结果表明, 在PMDA-ODA型聚酰亚胺前驱体中掺杂碳纳米管后, 碳纳米管与炭基体之间形成明显的“界面间隙”, 打破了原有炭膜中由乱层炭构成的无序微孔结构, 重新构建了杂化炭膜的孔隙结构. 与纯炭膜相比, 杂化炭膜的气体渗透速率大幅增加, 其中O₂的渗透速率增大接近4倍(达到1576 Barrer), 而O₂/N₂的分离选择性仅降低17%.     

PP/碳纳米管复合材料的制备及电性能

采用原子转移自由基(ATRP)活性聚合方法在多壁碳纳米管(MWNT)表面接枝丙烯酸丁酯聚合物(PBA),并以此对聚丙烯(PP)进行改性。红外光谱(FT-IR)及透射电子显微镜(TEM)测试结果表明,采用ATRP法成功地将PBA接枝到多壁碳纳米管(MWNT)表面。对PP/MWNT复合材料电性能研究表明,MWNT-PBA的添加比MWNT-COOH更能降低复合材料的电阻率。MWNT-PBA的加入可使PP从绝缘材料转变为抗静电材料。MWNT-PBA和MWNT-COOH加入PP都能提高材料的电性能,而MWNT-PBA比MWNT-COOH的作用更加明显。     

Highly Efficient Photoelectrocatalytic Reduction of CO2 to Methanol by a p–n Heterojunction CeO2/CuO/Cu Catalyst

Photoelectrocatalytic reduction of CO2 to fuels has great potential for reducing anthropogenic CO2 emissions and also lessening our dependence on fossil fuel energy.Herein,we report the successful development of a novel photoelectrocatalytic catalyst for the selective reduction of CO2 to methanol,comprising a copper catalyst modified with flower-like cerium oxide nanoparticles(CeO2 NPs)(a n-type semiconductor)and copper oxide nanoparticles(CuO NPs)(a p-type semiconductor).At an applied potential of−1.0 V(vs SCE)under visible light irradiation,the CeO2 NPs/CuO NPs/Cu catalyst yielded methanol at a rate of 3.44μmol cm^−2 h^−1,which was approximately five times higher than that of a CuO NPs/Cu catalyst(0.67μmol cm^−2 h^−1).The carrier concentration increased by^108 times when the flower-like CeO2 NPs were deposited on the CuO NPs/Cu catalyst,due to synergistic transfer of photoexcited electrons from the conduction band of CuO to that of CeO2,which enhanced both photocatalytic and photoelectrocatalytic CO2 reduction on the CeO2 NPs.The facile migration of photoexcited electrons and holes across the p–n heterojunction that formed between the CeO2 and CuO components was thus critical to excellent light-induced CO2 reduction properties of the CeO2 NPs/CuO NPs/Cu catalyst.Results encourage the wider application of composite semiconductor electrodes in carbon dioxide reduction.     

Effect of support size on the catalytic activity of metal-oxide-doped silica particles in the glycolysis of polyethylene terephthalate

Zinc oxide (ZnO) and cerium oxide (CeO2) nanoparticles were deposited on the surface of preformed silica spheres with diameters ranging from 60 to 750 nm. Ultrasonic irradiation was employed to promote the deposition of the metal oxide nanoparticles on the surface of silica. Silica-supported zinc oxide or cerium oxide was used as a catalyst in the glycolysis of polyethylene terephthalate, one of the key processes in the depolymerization of polyethylene terephthalate. The effect of the support size on the catalytic activity was studied in terms of monomer yield, and the monomer concentration was analyzed via high-performance liquid chromatography (HPLC). The morphologies and surface properties of the catalysts were characterized using a scanning electron microscope, a transmission electron microscope, and a BET surface area analyzer, while the monomer was characterized via HPLC and nuclear-magnetic-resonance spectroscopy. Both the zinc oxide and cerium oxide deposited on a smaller support showed better distribution and less aggregation. The high specific surface area of the smaller support catalysts provided a large number of active sites. The highest monomer yield was obtained with a catalyst of 60-nm silica support.     

Preparation and characterization of aligned carbon nanotube-ruthenium oxide nanocomposites for supercapacitors

A novel type of ruthenium oxide (RuO(2))-modified multi-walled carbon nanotube (MWNT) nanocomposite electrode (RuO(2)/MWNT) for supercapacitors has been prepared. The nanocomposites were formed by depositing Ru by magnetic-sputtering in an Ar/O(2) atmosphere onto MWNTs, which were synthesized on Ta plates by chemical vapor deposition. Cyclic voltammetry, chronopotentiometry, and electrochemical impedance measurements were applied to investigate the performance of the RuO(2)/MWNT nanocomposite electrodes. The capacitance of the MWNT electrodes in 1.0 M H(2)SO(4) is significantly increased from 0.35 to 16.94 mF cm(-2) by modification with RuO(2). The RuO(2) film on the surface of the nanotubes is composed of small crystal grains with tilted bundle-like microstructures, as observed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results demonstrate a promising route to prepare RuO(2)/MWNT-based double-layer supercapacitors.     

Effect of morphology of dispersed nano-CeO2 on far infrared emission property of natural tourmaline

Dispersed nano-CeO2 successfully grew on the surface of natural tourmaline powders by a precipitation method. The results of Fourier transform infrared spectroscopy (FTIR) showed that CeO2 (111) nanospots could apparently enhance the far infrared emission property of tourmaline in relation to CeO2 nanoparticles. This is the first report regarding the effect of the morphology of nano-CeO2 on the far infrared emission property of natural tourmaline. The results of the characterization by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) showed that CeO2 (111) nanospots have much more chemisorbed oxygen than CeO2 nanoparticles, which is beneficial to the unit cell volume shrinkage of tourmaline, thus increasing its far infrared emissivity.     

One pot synthesis and characterization of ultra fine CeO2 and Cu/CeO2 nanoparticles. Application for low temperature CO oxidation

Ultra fine cerium oxide and copper doped cerium oxide nanoparticles are prepared in a one-step reaction by thermal decomposition of Ce acetate in commercial oleylamine. The products are highly crystalline and were characterized by XRD, Raman spectroscopy, XPS, TEM and BET. The TEM images show that the CeO2 particles prepared are uniformly nanosized. The size of the nanoparticles can be controlled in the sub-10 nm range by the presence of other capping agent in the reaction mixture such as tri-octylphosphine oxide and oleic acid. The copper doped cerium oxide nanoparticles show high specific surface area (up to 299 m2/gr) and high catalytic activity for the low temperature CO oxidation even at low copper loading such as 9 at.%.     

Electrochemical fabrication of polyaniline/multi-walled carbon nanotube composite films for electrooxidation of methanol

Polyaniline (PANI)/multi-walled carbon nanotubes (MWNTs) composite films were fabricated by electropolymerization of aniline containing well-dissolved MWNTs. The films can be used as catalyst supports for electro-oxidation of methanol. Cyclic voltammogram and Chronoamperogram results show that platinum particles deposited on PANI/MWNT composite films exhibit higher electrocatalytic activity towards methanol oxidation than that deposited on pure PANI films. The porous structure and electrical conductivity of PANI films has been significantly changed by introduction of MWNTs, higher surface areas of PANI/MWNT composites has been achieved therefore. It favors for platinum particles to be highly dispersed on the PANI/MWNT composite films and the better electrocatalytic activity of Pt/PANI/MWNT electrode is induced consequently.     

测试介质对纳米CeO_2改性SPEEK膜质子电导率的影响

采用纳米氧化铈(CeO2)改性磺化度48.3%的磺化聚醚醚酮(SPEEK),通过溶液浇铸法制备用于直接甲醇燃料电池的质子交换膜.在两种介质中测试改性膜的电导率均随温度的升高而增大,与未改性膜相比却大小正好相反:在1 mol/L以盐酸溶液为电解液的测试介质中,改性膜的电导率是未改性膜的15倍,在水蒸气测试介质中,却仅为40%.红外光谱分析表明,CeO2中的铈原子与—SO3H基团中的氧原子发生配位作用.X射线衍射仪(XRD)分析可见,当复合膜浸入1 mol/L盐酸4 h前后,纳米CeO2的晶体结构未见明显变化,表明所发生的配位作用仅处于CeO2和SPEEK两个固相界面上.扫描电子显微镜(SEM)观察改性膜和未改性膜均无网络结构和微相分离,质子在膜内通过—SO3H基团之间的跃迁传导,酸溶液介质远比水蒸气有利于质子在纳米CeO2改性SPEEK膜内磺酸基团之间的跃迁.     

Growth of single and double walled carbon nanotubes over Co/V/MgO catalysts

High quality single walled carbon nanotubes (SWCNTs) and double walled carbon nanotubes (DWCNTs) were synthesized on Co/V/MgO catalysts by catalytic decomposition of CH₄ in H₂. Raman spectroscopy data revealed that the diameters of as-prepared SWCNTs are 1.28 and 0.73 nm. The diameter value of DWCNTs from Raman analysis also showed a narrow diameter distribution. Using field emission transmission electron microscopy (TEM), it was found that the diameter of carbon nanotubes can be controlled mainly by adjusting the molar ratio of Co–V versus the MgO support. The structure properties of catalysts were examined by X-ray diffraction (XRD). The formation of C₇V₈ may play an important role in preserving carbon in the catalyst particle and favoring the dissociation balance of CH₄.     

Preparation of carbon nanotube/chitosan/gold nanoparticle composite microspheres

The electrostatic layer-by-layer (LbL) assembly of acid-modified multi-walled carbon nanotubes (MWNTs) and biopolymer chitosan (CHIT) is realized on planar substrates and polystyrene (PS) microsphere templates, respectively. The successful stepwise growing process of the composite films on planar substrates is investigated and confirmed by scanning electron microscopy and UV-vis spectroscopy. The transfer of the LbL assembly of MWNTs and CHIT to spherical PS microspheres leads to novel (MWNT/CHIT)PS core-shell structure, on which the gold nanoparticles (GNPs) are deposited to fabricate GNP(MWNT/CHIT)PS composite microspheres. The glass carbon electrodes modified with such (MWNT/CHIT)PS or GNP(MWNT/CHIT)PS composites exhibit satisfactory electrocatalytic activities for biomolecule dopamine.     

Design of an Assembly of Poly(benzimidazole), Carbon Nanotubes,and Pt Nanoparticles for a Fuel‐Cell Electrocatalyst with an Ideal Interfacial Nanostructure

A newly designed and fabricated novel nanocomposite composed of multiwalled carbon nanotubes (MWNTs), poly(benzimidazole) (PBI), and Pt nanoparticles. This composite is fabricated by the preparation of PBI‐wrapped MWNTs (MWNT/PBI), followed by Pt loading onto the MWNT/PBI. As a result of the PBI wrapping, the loading efficiency of the Pt nanoparticles onto the MWNTs is dramatically improved up to 58.8% compared to that of the pristine MWNTs (41.0%). The process also allows homogeneous Pt immobilization onto the surface of MWNTs without any strong oxidation process for the MWNTs that is typically used for metal supporting on carbon nanotubes. Far‐IR spectroscopy of the composite shows a peak from the Pt? N bonding, indicating that these improvements are derived from the coordination of the Pt ion with the PBI molecules. Cyclic voltammogram measurements reveal that the Pt nanoparticles deposited on the MWNT/PBI shows higher utilization efficiency (74%) for electrocatalysts compared to that on the pristine MWNT (39%).     

MWNT reinforced polyurethane foam: Processing, characterization and modelling of mechanical properties

The mechanical properties of a foam material changes when the foam is reinforced with nanoparticles. In this paper it is investigated how the addition of multi-walled carbon nanotubes (MWNTs) influences the effective properties of polyurethane foam. Both pure and nano-reinforced foams containing different amounts of MWNT are produced and both pristine and functionalized MWNT are used as reinforcement. The MWNT are dispersed in the polyol using high-shear mixing with various mixing times to examine how that influences the properties of the produced foams. SEM is used to characterize the microstructure of the produced foams and these examinations reveals that the foam changes from a completely closed cell material for the pure PU foam to a partly open celled foam when adding MWNT. Compressive tests are performed in order to determine the strength and stiffness of the produced foams and the increase in these properties are very dependent on both the wt.% of MWNT and the mixing time used to disperse them in the polyol. Furthermore, the effective properties of the reinforced foams are determined using the Mori-Tanaka (MT) method and generally the correlation between the experimentally and numerically determined properties improves when the mixing time used increases for a constant wt.% of MWNT.