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51.
Yongsong Luo Xiaohong Xia Yonggang Zhang Jialin Li Zhijie Jia 《Journal of solid state chemistry》2007,180(6):1928-1933
Luminescence of the short multiwalled carbon nanotubes (MWNTs) conjugated with carboxylic acid groups has been studied. The results show that the carboxyl-functionalized short MWNTs could emit luminescence and the emission peak appears at 500 nm with a corresponding optimal excitation wavelength centering at 310 nm. When the short MWNTs are filtered through 0.15 μm polytetrafluoroethylene (PTFE) membrane, the ultrashort MWNTs are obtained from the filtrate. An interesting feature for the ultrashort MWNTs is that the emission intensity is strengthened and the peak is slightly blue shifted to 460 nm. This result indicates that the luminescence properties of MWNTs are strongly affected by the tube length. After chemical oxidization cutting, defects and carboxylic acid groups at the tube end and/or sidewall can be produced; the more shorten of MWNTs, the better dispersion and carboxylic passivation of the nanotubes, and the more intense luminescence emissions. The broad emissions are logically attributed to the trapping of excitation energy by defect sites in the carboxyl-functionalized nanotube structure. 相似文献
52.
Simple and sensitive electrochemical method for the determination of metronidazole, based on a nanostructured film coated glassy carbon electrode (GCE), is described. Multi-walled carbon nanotubes (MWNT) was dispersed into water in the presence of a hydrophobic surfactant to give very stable and homogeneous MWNT suspension, and a MWNT-film coated GCE was achieved via evaporating solvent. Metronidazole yields a well-defined reduction peak whose potential is −0.71 V at the MWNT-film coated GCE in pH 9.0 Britton-Robinson buffer. Compared with bare GCE, the MWNT-film modified GCE significantly enhances the reduction peak current of metronidazole. All the experimental parameters were optimized for the determination of metronidazole. The detection limit is 6×10−9 mol/l at 2 min accumulation. This method has been successfully used to determine metronidazole in the drugs. Furthermore, results obtained by the proposed method have been compared with spectrophotometric method. 相似文献
53.
CeO2 nanotubes have been synthesized facilely using carbon nanotubes (CNTs) as templates by a liquid phase deposition method. The properties of the CeO2 nanotubes were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectrum (XPS) as well as thermogravimetry and differential thermal analysis (TG-DTA). The obtained CeO2 nanotubes with a polycrystalline face-centered cubic phase have a uniform diameter ranging from 40 to 50 nm. The CeO2 nanotubes are composed of many tiny interconnected nanocrystallites of about 10 nm in size. The pretreatment of CNTs and calcination temperature were confirmed to be the crucial factors determining the formation of CeO2 nanotubes. A possible formation mechanism has been suggested to explain the formation of CeO2 nanotubes. 相似文献
54.
Kun Zhao Shuqi Zhuang Zhu Chang Haiyan Songm Liming Dai Pingang He Yuzhi Fang 《Electroanalysis》2007,19(10):1069-1074
A sensitive amperometric glucose biosensor based on platinum nanoparticles (PtNPs) combined aligned carbon nanotubes (ACNTs) electrode was investigated. PtNPs which can enhance the electrocatalytic activity of the electrode for electrooxidating hydrogen peroxide by enzymatic reaction were electrocrystallized on 4‐aminobenzene monolayer‐grafted ACNTs electrode by potential‐step method. These PtNPs combined ACNTs' (PtNPs/ACNTs) surfaces were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The highly dispersed PtNPs on ACNTs can be obtained. The enzyme electrode exhibits excellent response performance to glucose with linear range from 1×10?5–7×10?3 mol L?1 and fast response time within 5 s. Furthermore, this glucose biosensor also has good reproducibility. It is demonstrated that the PtNPs/ACNTs electrode with high electrocatalytic activity is a suitable basic electrode for preparing enzyme electrodes. 相似文献
55.
《Electroanalysis》2006,18(6):533-550
We review recent advances in biosensors based on one‐dimensional (1‐D) nanostructure field‐effect transistors (FET). Specifically, we address the fabrication, functionalization, assembly/alignment and sensing applications of FET based on carbon nanotubes, silicon nanowires and conducting polymer nanowires. The advantages and disadvantages of various fabrication, functionalization, and assembling procedures of these nanosensors are reviewed and discussed. We evaluate how they have been used for detection of various biological molecules and how such devices have enabled the achievement of high sensitivity and selectivity with low detection limits. Finally, we conclude by highlighting some of the challenges researchers face in the 1‐D nanostructures research arena and also predict the direction toward which future research in this area might be directed. 相似文献
56.
LiNi0.8Co0.2O2 / MWNTs复合物超级电容器电极材料的研究 总被引:2,自引:0,他引:2
Multiwalled carbon nanotubes (MWNTs) were used as the conductive additive in the electrode materials. The electrochemical properties of supercapacitors based on LiNi0.8Co0.2O2 / MWNTs composite and LiNi0.8Co0.2O2/acetylene black composite and MWNTs in 1.0 mol·L-1 LiClO4 / EC+DEC [V(EC)∶V(DEC)=1∶1] electrolyte were investigated by means of constant charge/discharge current tests, respectively. The experimental results show that the LiNi0.8Co0.2O2 / MWNTs composite has better performance than that of others, and the maximum specific capacitance of the supercapacitor can reach 271.6 F·g-1, while the energy density is up to 339.5 Wh·kg-1. Furthermore, it is remarkable that the performance of MWNTs is better than that of acetylene black as the conductive additive. 相似文献
57.
Reginald B. Little 《Journal of Cluster Science》2003,14(2):135-185
The discovery, synthesis, characterization, and applicability of carbon nanotubes have produced tremendous excitement and interest among scientists and engineers. In particular, the use of these unique tubular nanostructures for new strong lightweight materials, nanoelectronics, fuel storage and cells, electron emitters and bio, scanning probe microscopy, and chemical sensing devices has created an intense effort to advance the synthesis so as to mass produce carbon nanotubes with control over diameter and helicity. The massive and controlled synthesis of this heralded nanostructure has been a great challenge. Although significant progress has advanced the preparation, more synthetic development is required. The syntheses have so far involved three main approaches: arc discharge vaporization, laser vaporization, and catalytic chemical vapor deposition. The synthetic trend has progressed to a point where further advancement with these techniques will require a better understanding of the mechanism of nucleation and growth. The mechanics of carbon nanotube nucleation and growth involve very complex and diverse phenomena occurring under extreme conditions and on the mesoscopic scale. As yet the detail mechanism is unknown. Difficulties with experimental probing and computational simulation have increased the mystery of this mechanism. This review presents an account of research on the synthesis of carbon nanotubes and the mechanism of formation. This overview includes all three mentioned synthetic approaches and hybrids thereof. On the basis of this broad account a comprehensive mechanism for carbon nanotube nucleation and growth naturally arises. This mechanism is qualitative and it hopes to inspire more quantitative exploration and synthetic advancement. 相似文献
58.
59.
M. Sarah Mohlala 《Journal of organometallic chemistry》2006,691(22):4768-4772
A range of substituted ferrocenes were used as catalysts for the synthesis of multi-walled carbon nanotubes (MWCNTs) and carbon fibers (CFs). These products were obtained in the temperature range 800-1000 °C, in a reducing atmosphere of 5% H2 by pyrolysis of (CpR)(CpR′)Fe (R and R′ = H, Me, Et and COMe) in toluene solution. The effect of pyrolysis temperature (800-1000 °C), catalyst concentration (5 and 10 wt.% in toluene) and solution injection rate (0.2 and 0.8 ml/min) on the type and yield of carbonaceous product synthesized was investigated. Carbonaceous products formed include graphite film (mostly at high temperature; 900-1000 °C), carbon nanotubes and carbon fibers. The carbonaceous materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The ferrocene ring substituents influenced both the CNT diameter and the carbon product formed. 相似文献
60.
The semiconductor properties of the interface TiO2/electrolyte in high organized porous oxide structures were analyzed by means of impedance spectroscopy near the flat band
potential. The impedance and capacitance studies performed on the as-anodized and thermally treated samples (anatase) indicate
the presence of a duplex structure formed by (1) the oxide at the bottom of the pores and (2) the walls of pores with different
donor densities and surface state concentrations. 相似文献