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11.
We report a convenient method for quantitative non-covalent functionalization of single-walled carbon nanotubes (SWNT) with phthalocyanine (Pc) compounds, in which a surface coverage of 49% was achieved. The effect of several process parameters on the functionalization process was elucidated. Firstly, as-produced SWNT gave the largest extent of functionalization compared with purified SWNT and as-produced multi-walled carbon nanotubes (MWNT). Secondly, the extent of functionalization was sensitive to the specific molecular structures of the Pc compounds. Finally, in terms of solvent selection, dimethylformamide (DMF) was found to give the largest extent of functionalization, which is then followed by chloroform (CHCl3) and 1,2-dichlorobenzene (ODCB). The method reported in this paper provides new insights on the interactions between Pc molecules and carbon nanotubes and paves the way for rational control of the degree of functionalization, which is an important step from the perspective of carbon nanotube applications.
Electronic supplementary material Supplementary material for this article is avilable at and is accessible for authorised users. 相似文献
12.
AgI Microplate Monocrystals with Polar {0001} Facets: Spontaneous Photocarrier Separation and Enhanced Photocatalytic Activity
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Dr. Qin Kuang Xiaoli Zheng Prof. Shihe Yang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(9):2637-2645
Elucidating the facet‐dependent photocatalytic activity of semiconductor photocatalysts is important in improving the overall efficiency of photocatalysis. Furthermore, combining facet control with selective deposition of oxidation and/or reduction cocatalysts on specific faces of semiconductor photocatalysts is potentially an effective strategy to synergistically optimize the functionality of photocatalysts. In the present study, high‐purity wurtzite‐type β‐AgI platelet microcrystals with polar {0001} facets were prepared by a facile polyvinylpyrrolidone‐assisted precipitation reaction. The polar‐faceted AgI microplates were used as archetypes to demonstrate preferential diametric migration (i.e., effective separation) of photogenerated electrons and holes along the c axis. Such vectorial electron–hole separation stems from the asymmetric surface structures, which give rise to distinct photoexcited reaction behaviors on the ±(0001) polar facets of wurtzite‐type semiconductors. Furthermore, on selective deposition of Ag and MnOx (1.5<x<2) cocatalysts on the reductive (0001) and oxidative (000$\bar 1$ ) facets, respectively, photocatalytic activity of the AgI microplates in degrading organic pollutants was dramatically enhanced thanks to the broad light‐absorption range, strong dye‐adsorption ability, and effective spatial separation of photocarriers. 相似文献
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We report on the successful synthesis of silver sulfide (Ag(2)S) nanowires by a simple and mild gas-solid reaction approach. For the nanowire synthesis, a preoxidized silver substrate is exposed to an atmosphere of an O(2)/H(2)S mixture at room temperature or slightly above. The resulting Ag(2)S nanowires are phase pure with a monoclinic crystal structure and have diameters of a few tens of nanometers and lengths up to 100 mum. The influence of reaction conditions on the diameter, length, and morphology of the Ag(2)S nanowires has been studied by a number of structural and spectroscopic techniques. The nanowire growth mechanism on the Ag substrate has been discussed, which is likely characterized by continuous deposition at the tip. Additionally, we demonstrate thinning and cutting of individual Ag(2)S nanowires with electron beams and laser beams, which are potentially useful for nanowire manipulation and engineering. 相似文献
16.
The photochemistry of a gas-phase complex, Mg*(+)(2-fluoropyridine), has been studied in the spectral range of approximately 230-440 nm with a molecular beam coupled with a time-of-flight mass spectrometer. Surprisingly rich chemistry has been observed. Aside from the evaporative photofragment, Mg*(+), an abundant photoproduct, C(4)H(4)*(+), is observed after the electronic excitation of Mg(+). The formation of this photoproduct is associated with the loss of a stable species, CN[bond]Mg[bond]F. Also identified in this work are reactive pathways that occur with the elimination of HCN, HF, or MgF from the complex. The observed photoreactions have been examined in detail using quantum mechanics methods. A distinct structural feature of the complex is the direct attachment of Mg*(+) to the N atom of fluoropyridine due to the strong electrostatic interaction. The key to the rich photochemistry is the formation of the FMg(+)(C(5)H(4)N) intermediate, through facile fluorine migration. Plausible photoreaction mechanisms have been proposed. These mechanisms account for the evolution of the energized complex with the pre-defined structure en route to the target photoproducts that we have detected. 相似文献
17.
Shihe Xu 《Nonlinear Analysis: Real World Applications》2010,11(1):401-406
In this paper, a free boundary problem modeling tumor growth under the direct effect of an inhibitor with time delays is studied. The delays represent the time taken for cells to undergo mitosis. Nonnegativity of solutions, the existence of the stationary solutions and their asymptomatic behavior are studied. The results show that when the inhibitor is large, and the initial tumor is not too large, the tumor will disappear. If however, the initial tumor is large enough, then it will grow. When the inhibitor is not as large, the growth of the tumor is determined by the size of the nutrients and whether the initial tumor is large or not. When the inhibitor is smaller, the tumor will grow no matter if the initial tumor is large or not. 相似文献
18.
In this paper, a differentially heated square/cubic cavity is studied by performing three-dimensional direct numerical simulations. The first bifurcation observed at is due to the 3D vortex structures generated at the end regions of vertical boundary layers near the median plane. The main results of this Note are that the flow returns to a steady state for higher values of the Rayleigh number (7×107 and 108 for example) still exhibiting these 3D vortex structures, and that multiple steady flows which differ by their symmetry properties, are obtained for . However, the flow reverts to unsteadiness for . In this latter case, the instability is due to the vertical boundary layers. To cite this article: G. de Gassowski et al., C. R. Mecanique 331 (2003). 相似文献
19.
A numerical tool is developed for coupling natural convection in cavities with surface radiation and computations are performed for an air-filled square cavity whose four walls have the same emissivity. Compared to the adiabatic case without radiation, the top wall is cooled, the bottom wall is heated, air flow along the horizontal walls are reinforced and thermal stratification in cavity core is reduced. Detailed analysis shows that net radiative heat flux is linear with ΔT if , which is the case at low Rayleigh number, and that radiative Nusselt number is a linear function of the cavity height. Surface radiation induces an early transition to time-dependent flows: for and a cavity height of 0.335 m the critical Rayleigh number is equal to and the corresponding Hopf bifurcation is supercritical. Furthermore, multiple periodic solutions are observed between and . To cite this article: H. Wang et al., C. R. Mecanique 334 (2006). 相似文献
20.
Zhenghui Luo Fei Wu Teng Zhang Xuan Zeng Yiqun Xiao Tao Liu Cheng Zhong Xinhui Lu Linna Zhu Shihe Yang Chuluo Yang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(25):8608-8613
Electron transport materials (ETM) play an important role in the improvement of efficiency and stability for inverted perovskite solar cells (PSCs). This work reports an efficient ETM, named PDI‐C60, by the combination of perylene diimide (PDI) and fullerene. Compared to the traditional PCBM, this strategy endows PDI‐C60 with slightly shallower energy level and higher electron mobility. As a result, the device based on PDI‐C60 as electron transport layer (ETL) achieves high power conversion efficiency (PCE) of 18.6 %, which is significantly higher than those of the control devices of PCBM (16.6 %) and PDI (13.8 %). The high PCE of the PDI‐C60‐based device can be attributed to the more matching energy level with the perovskite, more efficient charge extraction, transport, and reduced recombination rate. To the best of our knowledge, the PCE of 18.6 % is the highest value in the PSCs using PDI derivatives as ETLs. Moreover, the device with PDI‐C60 as ETL exhibits better device stability due to the stronger hydrophobic properties of PDI‐C60. The strategy using the PDI/fullerene hybrid provides insights for future molecular design of the efficient ETM for the inverted PSCs. 相似文献