共查询到20条相似文献,搜索用时 15 毫秒
1.
以磺酸化的聚合物对多壁碳纳米管进行功能化,并以此为载体,采用室温下硼氢化钠还原法制备得到负载的Pd电催化剂,循环伏安(CV)和计时电流方法表明:功能化的碳纳米管为载体的Pd/MWCNTs催化剂对甲酸的电化学氧化具有较好的催化活性。 相似文献
2.
O. Yu. Ivanshina M. E. Tamm E. V. Gerasimova M. P. Kochugaeva M. N. Kirikova S. V. Savilov L. V. Yashina 《Inorganic Materials》2011,47(6):618-625
Pt/CNT nanocomposite materials with an average platinum particle size of 3–5 nm and platinum content of 13–28 wt % have been
prepared by reducing chloroplatinic acid, H2PtCl6, in the presence of conical carbon nanotubes. The effect of synthesis conditions on the average platinum particle size, total
platinum content, and surface composition of the nanocomposites has been studied using X-ray photoelectron spectroscopy, IR
spectroscopy, electron microscopy, X-ray diffraction, and thermogravimetry. The materials have been tested as catalysts for
hydrogen oxidation and oxygen reduction. Their performance has been assessed by cyclic and steady-state voltammetric techniques.
The structure and composition effects on the electrocatalytic properties of the nanocomposites are discussed. 相似文献
3.
Jing Xu Xian-Wen Wei Xiao-Jie Song Xiao-Jing Lu Chang-Chun Ji Yong-Hong Ni Guang-Chao Zhao 《Journal of Materials Science》2007,42(16):6972-6976
Cu–Ag bimetallic nanoparticles with atomic ratio of 2.1:1 and diameter in the range of 15–30 nm were decorated on acid-treated
multi-walled carbon nanotubes by a chemical reduction method, which was characterized by transmission electron microscope
(TEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy
(HRTEM). The Cu–Ag/MWNTs nanocomposites were used to construct a modified electrode toward biosensing of H2O2 with a high sensitivity. The catalytic ability of MWNTs/Cu–Ag toward H2O2 was much better than that of MWNTs/Cu and MWNTs/Ag, which indicated that there is a cooperation effect between Cu and Ag. 相似文献
4.
《Journal of Experimental Nanoscience》2013,8(5):742-751
Carbon nanotube (CNT)/silver nanocomposite powders with different volume fractions of CNTs 2.5, 5 and 10?vol.% were prepared by chemical reduction in solution. Multi-walled CNTs underwent surface modifications for functionalisations by acid treatments. The acid-treated CNTs were investigated by FT-IR and X-ray photoelectron spectroscopy. The spectroscopic investigations of the acid-functionalised CNTs detected that several kinds of functional groups attached with the graphene structure as well as produced short and de-caped CNTs. Acidic stannous chloride solution was used to sensitise the surface of the functionalised CNTs. Silver was deposited on the surface of sensitised CNTs with chemical reduction reaction of alkaline silver nitrate solution by formaldehyde at room temperature and pH?~?9. The morphology of the produced CNT/silver nanocomposite powder was investigated by high-resolution SEM and TEM. It was observed that the produced CNT/silver nanocomposite powders have decorated type of spherical silver particle size 2–5?nm deposited on the surface of CNTs as well as the CNTs were implanted in large spherical silver nanoparticles of particle size ~200?nm. The chemical analysis of the produced powder indicates that some oxygen content is included in the prepared powders which can be reduced by heat treatment at temperatures between 300°C and 400°C under hydrogen atmosphere. 相似文献
5.
Ning Wang 《Materials Research Bulletin》2011,46(9):1372-1376
A nanocomposite of SnO2 nanoparticles coated on multi-walled carbon nanotube (MWNT@SnO2) was synthesized and characterized by thermogravimetric analysis, X-ray diffraction, transmission electron microscopy, nitrogen physisorption measurements, photoluminescence. The results show that the SnO2 nanoparticles with a narrow size of 4 nm are uniformly deposited on MWNT. The photocatalytic activity of the nanocomposite was studied using methyl orange as a model organic pollutant. MWNT@SnO2 exhibits much higher photocatalytic activity than that of commercial TiO2 (P-25). The promotion is mainly contributed from electron transfer between SnO2 and MWNT. 相似文献
6.
7.
《Materials Letters》2007,61(8-9):1955-1958
A new method is used to grow macroscopic multi-walled carbon nanotube (MWNT) bundles with uniform diameter in bulk quantities. The diameter of the bundles are about 15–25 μm and their length is over 500 μm. The CNTs in each bundle are closely compact and parallel to each other along the direction of the bundle axis, which have potential applications as a composite enhancer or a high-strength nanostructure. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman analysis have been used to evaluate the morphological and structural features of such nanotube-based material. The formation mechanism of the bundles is discussed. 相似文献
8.
A pure metallic nickel nanoparticle, spherical in shape, has been successfully synthesized by the chemical reduction of nickel chloride with hydrazine at room temperature without any protective agent and inert gas protection. The effect of nickel salt concentration and the molar ratio of hydrazine to Ni2+ on the properties of the resultant products were investigated by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). Also, the reaction mechanism is discussed in this paper. This synthetic method is proven to be simple and very facile. In addition, it is very interesting to note that the obtained nickel nanoparticle can be isolated in the solid state and stabilized for several months in the atmosphere. 相似文献
9.
10.
Lyth SM Nabae Y Islam NM Kuroki S Kakimoto M Miyata S 《Journal of nanoscience and nanotechnology》2012,12(6):4887-4891
Fuel cells offer an alternative to burning fossil fuels, but use platinum as a catalyst which is expensive and scarce. Cheap, alternative catalysts could enable fuel cells to become serious contenders in the green energy sector. One promising class of catalyst for electrochemical oxygen reduction is iron-containing, nanostructured, nitrogen-doped carbon. The catalytic activity of such N-doped carbons has improved vastly over the years bringing industrial applications ever closer. Stoichiometric carbon nitride powder has only been observed in recent years. It has nitrogen content up to 57% and as such is an extremely interesting material to work with. The electrochemical activity of carbon nitride has already been explored, confirming that iron is not a necessary ingredient for 4-electron oxygen reduction. Here, we synthesize carbon nitride on a carbon nanotube support and subject it to high temperature treatment in an effort to increase the surface area and conductivity. The results lend insight into the mechanism of oxygen reduction and show the potential for carbon nanotube-supported carbon nitride to be used as a catalyst to replace platinum in fuel cells. 相似文献
11.
A combined hot-injection and heat-up method was developed to synthesize monodisperse and uniform CoMn2O4 quantum dots (CMO QDs).CMO QDs with average size of 2.0,3.9,and 5.4 nm were selectively obtained at 80,90,and 105 ℃,respectively.The CMO QDs supported on carbon nanotubes (CNTs) were employed as catalysts for the oxygen reduction/evolution reaction (ORR/OER) in alkaline solution to investigate their size-performance relationship.The results revealed that the amount of surface-adsorbed oxygen and the band gap energy,which affect the charge transfer in the oxygen electrocatalysis processes,strongly depend on the size of the CMO QDs.The CMO-3.9/CNT hybrid,consisting of CNT-supported CMO QDs of 3.9 nm size,possesses a moderate amount of surfaceadsorbed oxygen,a lower band gap energy,and a larger charge carrier concentration,and exhibits the highest electrocatalytic activity among the hybrid materials investigated.Moreover,the CMO-3.9/CNT hybrid displays ORR and OER performances similar to those of the benchmark Pt/C and RuO2 catalysts,respectively,due to the strong carbon-oxide interactions and the high dispersion of CoMn2O4 QDs on the carbon substrate;this reveals the huge potential of the CMO-3.9/CNT hybrid as a bifunctional OER/ORR electrocatalyst.The present results highlight the importance of controlling the size of metal oxide nanodots in the design of active oxygen electrocatalysts based on spinel-type,nonprecious metal oxides. 相似文献
12.
MnOx-doped carbon nanotube (MnOx-CNTs) catalysts for the oxygen reduction reaction (ORR) were fabricated using a simple electrochemical deposition method. MnOx-CNTs (0.85 wt % MnOx) could exhibit an improved electrocatalytic activity, long-term stability and excellent resistance to crossover-effect compared to Pt/C catalysts. High-resolution transmission electron microscopy (HRTEM) and X-ray diffraction analysis confirm that the MnOx in the MnOx-CNTs exists in an amorphous state. Moreover, compared to the catalytic performances of MnOx on other substrates, the MnOx-CNTs exhibit a high ORR activity. X-ray photoelectron spectroscopy results suggest that the electron transfer, from the CNTs to the Mn ions occurs and the high positive charge is generated on the MnOx-CNT surface. This is believed to be origin of the catalytic activity observed in the ORR using MnOx-CNTs. 相似文献
13.
Composites of carbon nanotubes with attached carboxylic groups (c-MWCNTs) and water-soluble externally doped sulfonated polyaniline (ED-SPANI) were prepared by solution mixing of c-MWCNT and ED-SPANI aqueous colloids. Fourier-transform infrared spectroscopy, Raman spectroscopy, ultraviolet–visible (UV–Vis) absorption spectroscopy, field-emission scanning and high-resolution transmission electron microscopy were used to characterize their structure and morphology. Raman and UV–Vis spectra revealed the presence of electrostatic interaction between the C–N+ species of the ED-SPANI and the COO− species of the c-MWCNTs. The addition of c-MWCNT to ED-SPANI can improve its thermal stability. The conductivity of 3 wt.% ED-SPANI/c-MWCNT composites at room temperature is sixteen times higher than that of ED-SPANI. These results demonstrate that the addition of a small number of c-MWCNTs to an ED-SPANI matrix can form a conducting network in well dispersed composites, thus increasing their electrical conductivity. 相似文献
14.
Yexin Zhang Chunlin Chen Lixia Peng Zhongsen Ma Yajie Zhang Hengheng Xia Aili Yang Lei Wang Dang Sheng Su Jian Zhang 《Nano Research》2015,8(2):502-511
Ozone treatment is a common way to functionalize commercial multi-walled carbon nanotubes (CNTs) with various oxygen functionalities like carboxyl, phenol and lactone groups, in order to enhance their textural properties and chemical activity. In order to detail the effect of each functional group, we correlated the activity with the surface density of each group, and found that the carboxyl groups play a pivotal role in two important catalytic reactions, namely the electrochemical oxygen reduction reaction (ORR) and agar conversion to 5-hydroxymethylfurfural (HMF). During the processes, the hydrophilic surface provides a strong affinity for reaction substrates while the improved porosity allows the efficient diffusion of reactants and products. Furthermore, the activity of functionalized CNTs for agar conversion remained almost unchanged during nine cycles of reaction. This work highlights a strategy for improving the activity of CNTs for electrochemical ORR and agar conversion reactions, as well a promising application of carboxyl-rich CNTs as a solid acid catalyst to produce high-purity HMF—an important chemical intermediate. 相似文献
15.
Gao YB Wang Y Wang JY Xu SY Wei XL Wang MS Li Y Peng LM 《Journal of nanoscience and nanotechnology》2010,10(8):4985-4991
We report here a method for measurement of thermoelectric power of quasi-one dimensional nano-materials with a simple platform, where individual nanomaterial is assembled with nano-probes in a scanning electron microscope. This approach allows repeated manipulation and thermoelectric measurement of the same loaded nanosample with adjustable number of individual nanotubes or nanowires. It also allows assembly of multiple samples on one measurement stage. For multi-walled carbon nanotube bundles, we have observed a weak trend that, when the number of individual tubes in a bundle varies from ten millions to around a hundred thousand, the thermoelectric power almost remains at around 10 microV/K. When the tube number in the bundle is further reduced, the up-limit of the thermoelectric power gradually increases to a value near 20 microV/K. 相似文献
16.
以聚二甲基二烯丙基氯化铵功能化石墨烯(PDDA-GNs)和磷钼酸功能化石墨烯(PMo12-GNs)为原料,利用层层自组装法制备了功能化石墨烯多层膜({PDDA-GNs/PMo12-GNs}),以此多层膜为载体,通过恒电位电沉积法制备功能化石墨烯多层膜载金催化剂(Au/{PDDA-GNs/PMo12-GNs}n)。采用XRD、XPS和SEM等表征Au/{PDDA-GNs/PMo12-GNs}n催化剂的组成、结构和形貌。结果表明:实验成功制备了Au/{PDDA-GNs/PMo12-GNs}n催化剂,且多层膜载体改善了Au粒子的分散性。利用循环伏安(CV)、计时电流(It)和交流阻抗(EIS)等评价催化剂对肼氧化的电催化性能。结果表明,Au/{PDDA-GNs/PMo12-GNs}n催化剂使肼氧化的电催化活性和稳定性得到很大提高。与Au/玻碳电极(GCE)相比,Au/{PDDA-GNs/PMo12-GNs}n催化肼氧化反应的峰电流密度从0.46 mA/cm2提高到0.87 mA/cm2,600 s时的稳态电流密度是Au/GCE的2.5倍。 相似文献
17.
A water/oil microemulsion system having been successfully used for synthesizing polyaniline(PANi) nanoparticles, was employed for preparing PANi/multi-walled carbon nanotube (MWCNT) nanocomposites via in situ chemical oxidative polymerization. The structures and the electrical property of PANi/MWCNT nanocomposites were also studied. The studies showed that PANi could coat MWCNTs to form nanocables with core-shell structure, and the backbone structure of PANi was not damaged by the introduction of MWCNTs. The conductivities of PANi/MWCNT nanocomposites were higher than that of PANi. Moreover, a model was supposed to be used for describing a PANi/MWCNT nanocable formation by in situ microemulsion polymerization. 相似文献
18.
Well dispersed nickel nanoparticles with uniform size were synthesized via a modified hydrazine reduction route without any surfactant introduced. Ethanol was used as solvent and played the complementary reducing role. The as-prepared samples were characterized by XRD, FESEM, TEM and TG. Pure metallic Ni could be easily obtained when ethanol instead of water was used as solvent. The particle surface was much improved when ethanol was involved in the reduction process at high temperature. The resultant particles have smooth surface and uniform size of about 50 nm. The nickel powders have an oxidization temperature of about 200 °C. The formation process was discussed based on the experimental results. 相似文献
19.
Fabrication of multi-walled carbon nanotube reinforced polyelectrolyte hollow nanofibers by electrospinning 总被引:1,自引:0,他引:1
Hybrid hollow multi-walled carbon nanotubes (MWCNTs)/polyelectrolytes (PE) nanofibers were prepared by a combination of the electrospinning method and layer-by-layer (LbL) technique. The mixed polystyrene (PS)/MWCNTs nanofibers were obtained by electrospinning method, which were employed as templates to self-assembly multilayered polyelectrolytes by LbL technique. Hollow MWCNTs/PE nanofibers were obtained by selectively removed part of the template: PS, which is confirmed by Raman spectra, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). 相似文献
20.
Multi-walled carbon nanotubes (MWCNTs) were produced by chemical vapor decomposition using acetylene gas in the presence of Ferrocene catalyst at 800 degrees C, and then oxidized with concentrated nitric acid at 150 degrees C. Both (as-produced and oxidized) CNTs were characterized by TEM, Boehm titration, N2-BET and cation exchange capacity techniques. The adsorption capacity for nickel ions from aqueous solutions increased significantly onto the surface of the oxidized CNTs compared to that on the as-produced CNTs. The effects of adsorption time, solution pH and initial nickel ions concentrations on the adsorption uptake of Ni2+ for both the as-produced and oxidized CNTs were investigated at room temperature. Both Langmuir and Freundlich isotherm models match the experimental data very well. According to the Langmuir model the maximum nickel ions adsorption uptake onto the as-produced and oxidized CNTs were determined as 18.083 and 49.261 mg/g, respectively. Our results showed that CNTs can be used as an effective Ni2+ adsorbent due to the high adsorption capacity as well as the short adsorption time needed to achieve equilibrium. 相似文献