Synthesis and properties of iron oxide coated carbon nanotubes hybrid materials and their use in epoxy coatings

In this paper, Cu2O/multi-walled carbon nanotube (Cu2O/MWCNT) hybrid material was successfully synthesized by a precipitation method. The constituent, morphology, structure, interaction, and electromagnetic parameters of the Cu2O/MWCNT hybrid material were tested by XRD, SEM, TEM, XPS, FT-IR, TGA, and vector network analysis. The results show that Cu2O nano-particles are randomly deposited on the MWCNTs, the interaction is a chemical force between Cu atoms belonging to Cu2O nano-particles and C=O associated with MWCNTs, and the hybrid material exhibits outstanding microwave absorption ability. When the thickness of the absorber is 1.5 mm, the optimal reflection loss (RL) of the electromagnetic wave is up to −28.8 dB at 11.9 GHz, and the valid bandwidth (RL ≤ −10 dB) is approximately 2.7 GHz (10.7–13.4 GHz). When the thickness of the absorber is 2.0 mm, the optimal RL of the electromagnetic wave is −40.5 dB at 8.1 GHz. The hybrid material has excellent microwave-absorption properties, likely due to its polarization, conductive network, and special interface structure.

Multiwalled carbon nanotubes (MWCNTs) were acidified with nitration mixture; the silicon oxide-coated MWCNTs (SiO2-MWCNTs) hybrid material was then prepared via the sol–gel method, and the results were verified using scanning electron microscopy (SEM), X-ray diffraction, and thermogravimetric analysis (TGA). We modified the hybrid material with silane coupling agent (KH560) and prepared SiO2-MWCNTs/epoxy, MWCNTs/epoxy composite coating, and the pure epoxy coating, respectively. The impedance performance was tested using electrochemical workstation (electron ionization spray); then, the mechanical properties and thermal stability were tested through the shock experiments and TGA. Finally, we used SEM to observe the coating surface condition. The results show that SiO2-MWCNTs have a good dispersion in the epoxy resin and the mechanical properties and corrosion resistance of SiO2-MWCNTs/epoxy composite coating have enhanced.

In situ synthesis of graphene/single-walled carbon nanotube hybrid material by arc-discharge and its application in supercapacitors

Graphene and carbon nanotubes have received much attention for thermal management application due to their unique thermal performance. Theoretical work suggests that a covalent bond can combine 1D carbon nanotubes with 2D graphene together to extend the excellent thermal property to three dimensions for heat dissipation. This paper experimentally demonstrates the high heat dissipation capability of a freestanding 3D multiwall carbon nanotube (MWCNT) and graphene hybrid material. Using high‐resolution transmission electron microscopy and pulsed photothermal reflection measurement method, the covalent bonds between MWCNT and planar graphene are microscopically and numerically demonstrated. Thermal resistance at the junction with covalent bonds is 9 × 10−10 m2 KW−1, which is three orders of magnitude lower than van der Waals contact. Joule heating method is used to verify the extra cooling effect of this 3D hybrid material compared to graphite film. A demonstrator using high power chip is developed to demonstrate the applicability of this hybrid material in thermal application. Temperature at hot spots can be decreased by around 10 °C with the assistance of this hybrid material. These findings are very significant for understanding the thermal conduction during combining 1D and 2D carbon material together for future thermal management application.

Chapter 4 - Carbon Nanotube Hybrid Materials

Zinc oxide (ZnO) decorated multi-walled carbon nanotubes (MWCNTs) hybrid material was prepared to improve the tribological performance of chemically bonded ceramic coatings. TEM results reveal that ZnO has been successfully fabricated on the surface of MWCNTs. The tribological performance of the ceramic coatings with MWCNTs–ZnO hybrid material was investigated using a ball-on-disc method. The results show that the friction coefficient and wear rate of the ceramic coatings decrease with the increase of MWCNTs–ZnO hybrid material. The ceramic coatings with MWCNTs-ZnO hybrid material shows a smooth worn surface with less cracks and delamination. In addition, the worn surface of the counterpart ball shows a smaller worn area and a smooth surface. The excellent wear resistance of the ceramic coatings is attributed to the good bonding strength between MWCNTs–ZnO hybrid material and ceramic matrix.

Nanomaterials and nanocomposites have gained relevance in science and technology due to their excellent properties. Therefore, the characterization of these materials is important. Thermogravimetric analysis is a powerful technique for the characterization of iron-carbon nanotubes (Fe/MWCNT) as hybrid nanomaterials, which may be prepared by impregnation step (alkaline or microwave-assisted precipitation). High-resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD and in situ XRD), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA) were the instrumental techniques used to characterize these hybrid materials. Through TGA, it was possible to determine the quantity of effective impregnated iron on the MWCNT. Further, in a TGA, nitrogen atmosphere reveals a thermal event reflecting the iron reduction by C from MWCNT and the shape of the signal reflects the dispersion and size of the iron particles on the surface. This thermal event is related to the particle sizes and chemical nature of iron oxides present. Thermal events from TGA may be correlated with the results obtained from XRD, XPS, and HR-TEM. The presence of smaller and well-distributed iron nanoparticles impacts the shape of the reducing event in the TGA. The reduction temperature as observed in TGA curves is related to the nature of metal compounds present, such as nitrates or oxides. These results suggest that TGA can be used as a rapid and economical technique for the evaluation of different Fe/MWCNT hybrid material properties. These results may facilitate the estimation of the structural and chemical nature of the Fe/MWCNT nanohybrid materials and permit the projections of potential applications.

CoFe(2)O(4)/multiwalled carbon nanotubes (MWCNTs) hybrid materials were synthesized by a hydrothermal method. Field emission scanning electron microscopy and transmission electron microscopy analysis confirmed the morphology of the as-prepared hybrid material resembling wintersweet flower "buds on branches", in which CoFe(2)O(4) nanoclusters, consisting of nanocrystals with a size of 5-10 nm, are anchored along carbon nanotubes. When applied as an anode material in lithium ion batteries, the CoFe(2)O(4)/MWCNTs hybrid material exhibited a high performance for reversible lithium storage. In particular, the hybrid anode material delivered reversible lithium storage capacities of 809, 765, 539, and 359 mA h g(-1) at current densities of 180, 450, 900, and 1800 mA g(-1), respectively. The superior performance of CoFe(2)O(4)/MWCNTs hybrid materials could be ascribed to the synergistic pinning effect of the wintersweet-flower-like nanoarchitecture. This strategy could also be applied to synthesize other metal oxide/CNTs hybrid materials as high-capacity anode materials for lithium ion batteries.

One-step growth of graphene–carbon nanotube hybrid materials by chemical vapor deposition

Preparation of conjugated polymer-based composite thin film for application in solar cell

A convenient approach for the preparation of cellulose ‐ carbon nanotubes (CNT) hybrid materials owning electromagnetic shielding properties, based on viscose (V) and TEMPO‐oxidized viscose fibers (VO) is proposed. Viscose ‐ carbon nanotubes (V‐CNT) and TEMPO‐oxidized viscose ‐ carbon nanotubes (VO‐CNT) composites were prepared by embedding carbon nanotubes on the surface of two types of cellulose fibers, that is, viscose and its C6‐oxidized derivative. The chemical composition, morphology, and thermal stability of the prepared hybrid materials were thoroughly investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analyses. Moreover, electrical properties of the original and composite fibers were assessed. POLYM. ENG. SCI., 59:1499–1506 2019. © 2019 Society of Plastics Engineers

Microwave-induced fabrication of copper nanoparticle/carbon nanotubes hybrid material

We report the synthesis and characterization of adenine-single-walled carbon nanotube (SWCNT) hybrid materials, where for the first time nucleobases are covalently attached to the exosurface of SWCNTs. The structural properties of all hybrids have been characterized using usual spectroscopic and microscopic techniques. The degree of functional groups for functionalized SWCNTs (f-SWCNTs) 2a and 2b is one adenine group for each 26 and 37 carbon atoms, respectively. Solid-state magic angle spinning (13)C NMR spectroscopy (MAS NMR) and electrochemistry have been also applied for the characterization of these f-SWCNTs. AFM images of f-SWCNT 2b showed an interesting feature of horizontally aligned nanotubes along the surface when deposited on highly oriented pyrolytic graphite surface. Furthermore, we evaluated the coordinating ability of these hybrid materials toward silver ions, and interestingly, we found a pattern of silver nanoparticles localized over the surface of the carbon nanotube network. The presence of aligned and randomly oriented CNTs and their ability to coordinate with metal ions make this class of materials very interesting for applications in the development of novel electronic devices and as new supports for different catalytic transformations.

建立高效、灵敏的农药分离、富集和检测方法具有重要意义。该实验采用一步法合成了钴基沸石咪唑骨架/多壁碳纳米管(ZIF-67/MWCNTs)复合物,并以该复合物为模板通过溶剂热法合成了钴镍笼状双金属氢氧化物/多壁碳纳米管(CoNi-LDH/MWCNTs)复合材料,将CoNi-LDH/MWCNTs用作固相微萃取(SPME)的纤维涂层富集环境水样中的6种农药,结合高效液相色谱(HPLC)测定了环境水样中的6种农药。通过扫描电镜、能谱分析、红外光谱、粉末X射线衍射和N2吸附/脱附对所制备的各种材料进行了表征。利用正交设计试验优化SPME的萃取条件,包括萃取温度、萃取时间、搅拌速率、解吸时间和盐浓度。在最优化的条件下,该方法具有较宽的线性范围(百菌清为0.015~200 μg/L,戊唑醇为0.140~200 μg/L,毒死蜱为0.250~200 μg/L,仲丁灵为0.077~200 μg/L,溴氰菊酯为1.445~200 μg/L,哒螨灵为0.964~200 μg/L)、较低的检出限(0.004~0.434 μg/L)和良好的重复性。单个纤维和不同批次纤维间的相对标准偏差(RSD)分别为0.5%~5.7%和0.5%~4.8%。在10.0 μg/L和50.0 μg/L 2个水平下的加标回收率为83.9%~108.2%, RSD< 5.3%。此外,与其他涂层纤维相比,CoNi-LDH/MWCNTs涂层对农药具有更高效的富集能力,这归因于它的高比表面积以及CoNi-LDH/MWCNTs涂层与目标分析物之间存在的π-π堆积作用、疏水作用、阳离子-π相互作用和氢键作用。该方法可以实现环境水样中农药残留的高选择性、高灵敏度及高准确性的分析测定。

A new method which utilizes a polypropylene amine dendrimers (POPAM)-grafted multi-walled carbon nanotubes (MWCNTs) hybrid materials as an effective sorbent in solid-phase extraction has been developed for separation and preconcentration of Au(III) and Pd(II) trace levels in food, water and soil samples. The optimum experimental conditions such as pH, flow rates, type, concentration, and volume of the eluent for elution of gold and palladium ions, breakthrough volume, and effect of potentially interfering ions on separation and determination of these noble metals were investigated. The extraction recoveries for the mentioned noble metals were greater than 98 % and the limits of detection were 0.08 and 0.12 ng mL−1 for gold and palladium, respectively. The relative standard deviations of the method were less than 4 % for eight separate column experiments for determination of 5.0 μg of gold and palladium ions. The adsorption capacity of the modified MWCNT was 92 mg g−1 for gold and 74 mg g−1 for palladium on POPAM-grafted MWCNTs. Validation of the suggested method was performed by analyzing certified reference materials. Finally, the proposed method was applied for determination of gold(III) and palladium(II) in real samples, including fish, shrimp, water, and soil.