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91.
Kyo-Hong CHOI Kwon-Koo CHO Gyu-Bong CHO Hyo-Jun AHN Ki-Won KIM Yoo-Young KIM 《材料科学与工程学报》2007,25(6):886-891
Several researches have been reported about the characteristic of β-Ga2O3 nanowires which was synthesized on nickel oxide particle. But indeed, recent researches about synthesis of β-Ga2O3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide catalyst. In this work, Gallium oxide (β-Ga2O3 ) nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700 - 1000℃ using the iron, nickel, copper, cobalt and zinc oxide as a catalyst, respectively. The β-Ga2O3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850, 900 and 950℃ in all the catalysts. But optimum experimental condition in synthesis of nanowires varied with the kind of catalyst. As increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods, and its diameter increased. From these results, we could be proposed that the growth mechanism of β-Ga2O3 nanowires was changed with synthesis temperature of nanowires. Microstructure and morphology of Synthesized nanowire was characterized by HR-TEM, FE-SEM, EDX and XRD. 相似文献
92.
《Advanced Powder Technology》2020,31(8):3650-3656
In this study, Eu3+-containing amorphous silica nanoparticles and Eu compounds were successfully synthesized via a mechanochemical solid-state reaction between silica nanoparticles and EuCl3·6H2O. This reaction was induced by a grinding process, and the states of Eu3+ in the silica/europium composites were investigated. The silica/europium composites exhibited orange–red color luminescence owing to the 5D0–7F0, 5D0–7F1, and 5D0–7F2 transitions, which indicated the presence of Eu3+ in the silica framework and the newly formed Eu compounds such as EuOCl and Eu(OH)2Cl. The mechanochemical reaction because of the grinding process effectively induced an interaction between the silica surface and europium chloride; subsequently, Eu(OH)2Cl was formed in the silica/europium composites. Additionally, the Eu(OH)2Cl in the silica/europium composite exhibited a higher thermal stability than that of simple Eu(OH)2Cl, indicating that the mechanochemical reaction mediated the formation of Eu(OH)2Cl and new chemical bonding between the newly formed Eu(OH)2Cl and the silica surface, providing improved thermal stability to Eu(OH)2Cl. Thus, we successfully prepared silica nanoparticles containing not only Eu(III) in the silica framework but also Eu compounds that exhibit unique chemical bonding during a mechanochemical reaction. 相似文献
93.
A. Amezcua‐Correa J. Yang C. E. Finlayson A. C. Peacock J. R. Hayes P. J. A. Sazio J. J. Baumberg S. M. Howdle 《Advanced functional materials》2007,17(13):2024-2030
Microstructured optical fibers (MOFs) represent a promising platform technology for fully integrated next generation surface enhanced Raman scattering (SERS) sensors and plasmonic devices. In this paper we demonstrate silver nanoparticle substrates for SERS detection within MOF templates with exceptional temporal and mechanical stability, using organometallic precursors and a high‐pressure chemical deposition technique. These 3D substrates offer significant benefits over conventional planar detection geometries, with the long electromagnetic interaction lengths of the optical guided fiber modes exciting multiple plasmon resonances along the fiber. The large Raman response detected when analyte molecules are infiltrated within the structures can be directly related to the deposition profile of the nanoparticles within the MOFs via electrical characterization. 相似文献
94.
K. S. Soppimath L.‐H. Liu W. Y. Seow S.‐Q. Liu R. Powell P. Chan Y. Y. Yang 《Advanced functional materials》2007,17(3):355-362
Core/shell nanoparticles that display a pH‐sensitive thermal response, self‐assembled from the amphiphilic tercopolymer, poly(N‐isopropylacrylamide‐co‐N,N‐dimethylacrylamide‐co‐10‐undecenoic acid) (P(NIPAAm‐co‐DMAAm‐co‐UA)), have recently been reported. In this study, folic acid is conjugated to the hydrophilic segment of the polymer through the free amine group (for targeting cancer cells that overexpress folate receptors) and cholesterol is grafted to the hydrophobic segment of the polymer. This polymer also self‐assembles into core/shell nanoparticles that exhibit pH‐induced temperature sensitivity, but they possess a more stable hydrophobic core than the original polymer P(NIPAAm‐co‐DMAAm‐co‐UA) and a shell containing folate molecules. An anticancer drug, doxorubicin (DOX), is encapsulated into the nanoparticles. DOX release is also pH‐dependent. DOX molecules delivered by P(NIPAAm‐co‐DMAAm‐co‐UA) and folate‐conjugated P(NIPAAm‐co‐DMAAm‐co‐UA)‐g‐cholesterol nanoparticles enter the nucleus more rapidly than those transported by P(NIPAAm‐co‐DMAAm)‐b‐poly(lactide‐co‐glycolide) nanoparticles, which are not pH sensitive. More importantly, these nanoparticles can recognize folate‐receptor‐expressing cancer cells. Compared to the nanoparticles without folate, the DOX‐loaded nanoparticles with folate yield a greater cellular uptake because of the folate‐receptor‐mediated endocytosis process, and, thus, higher cytotoxicity results. These multifunctional polymer core/shell nanoparticles may make a promising carrier to target drugs to cancer cells and release the drug molecules to the cytoplasm inside the cells. 相似文献
95.
Y. Yin C.K. Erdonmez A. Cabot S. Hughes A.P. Alivisatos 《Advanced functional materials》2006,16(11):1389-1399
Formation of cobalt sulfide hollow nanocrystals through a mechanism similar to the Kirkendall Effect has been investigated in detail. It is found that performing the reaction at > 120 °C leads to fast formation of a single void inside each shell, whereas at room temperature multiple voids are formed within each shell, which can be attributed to strongly temperature‐dependent diffusivities for vacancies. The void formation process is dominated by outward diffusion of cobalt cations; still, the occurrence of significant inward transport of sulfur anions can be inferred as the final voids are smaller in diameter than the original cobalt nanocrystals. Comparison of volume distributions for initial and final nanostructures indicates excess apparent volume in shells, implying significant porosity and/or a defective structure. Indirect evidence for fracture of shells during growth at lower temperatures was observed in shell‐size statistics and transmission electron microscopy images of as‐grown shells. An idealized model of the diffusional process imposes two minimal requirements on material parameters for shell growth to be obtainable within a specific synthetic system. 相似文献
96.
Nanomaterials for environmental studies: Classification, reference material issues, and strategies for physico-chemical characterisation 总被引:1,自引:0,他引:1
Vicki Stone Bernd Nowack Nico van den Brink Maria Dusinska Steven Hankin Erik Joner 《The Science of the total environment》2010,408(7):1745-1754
NanoImpactNet is a European Commission Framework Programme 7 (FP7) funded project that provides a forum for the discussion of current opinions on nanomaterials in relation to human and environmental issues. In September 2008, in Zurich, a NanoImpactNet environmental workshop focused on three key questions:
- 1.
- What properties should be characterised for nanomaterials used in environmental and ecotoxicology studies?
- 2.
- What reference materials should be developed for use in environmental and ecotoxicological studies?
- 3.
- Is it possible to group different nanomaterials into categories for consideration in environmental studies?
97.
Zero valent iron (ZVI) nanoparticles have been studied extensively for degradation of chlorinated solvents in the aqueous phase, and have been tested for in-situ remediation of contaminated soil and groundwater. However, little is known about its effectiveness for degrading soil-sorbed contaminants. This work studied reductive dechlorination of trichloroethylene (TCE) sorbed in two model soils (a potting soil and Smith Farm soil) using carboxymethyl cellulose (CMC) stabilized Fe-Pd bimetallic nanoparticles. Effects of sorption, surfactants and dissolved organic matter (DOC) were determined through batch kinetic experiments. While the nanoparticles can effectively degrade soil-sorbed TCE, the TCE degradation rate was strongly limited by desorption kinetics, especially for the potting soil which has a higher organic matter content of 8.2%. Under otherwise identical conditions, ∼44% of TCE sorbed in the potting soil was degraded in 30 h, compared to ∼82% for Smith Farm soil (organic matter content = 0.7%). DOC from the potting soil was found to inhibit TCE degradation. The presence of the extracted SOM at 40 ppm and 350 ppm as TOC reduced the degradation rate by 34% and 67%, respectively. Four prototype surfactants were tested for their effects on TCE desorption and degradation rates, including two anionic surfactants known as SDS (sodium dodecyl sulfate) and SDBS (sodium dodecyl benzene sulfonate), a cationic surfactant hexadecyltrimethylammonium (HDTMA) bromide, and a non-ionic surfactant Tween 80. All four surfactants were observed to enhance TCE desorption at concentrations below or above the critical micelle concentration (cmc), with the anionic surfactant SDS being most effective. Based on the pseudo-first-order reaction rate law, the presence of 1×cmc SDS increased the reaction rate by a factor of 2.5 when the nanoparticles were used for degrading TCE in a water solution. SDS was effective for enhancing degradation of TCE sorbed in Smith Farm soil, the presence of SDS at sub-cmc increased TCE degraded by ∼10%. However, effect of SDS on degradation of TCE in the potting soil was more complex. The presence of SDS at sub-cmc decreased TCE degradation by 5%, but increased degradation by 5% when SDS dosage was raised to 5×cmc. The opposing effects were attributed to combined effects of SDS on TCE desorption and degradation, release of soil organic matter and nanoparticle aggregation. The findings strongly suggest that effect of soil sorption on the effectiveness of Fe-Pd nanoparticles must be taken into account in process design, and soil organic content plays an important role in the overall degradation rate and in the effectiveness of surfactant uses. 相似文献
98.
Hend Omar Mohamed Enas Taha Sayed M. Obaid Yun-Jeong Choi Sung-Gwan Park Siham Al-Qaradawi Kyu-Jung Chae 《International Journal of Hydrogen Energy》2018,43(46):21560-21571
The poor wettability and high cost of the carbonaceous electrodes materials prohibited the practical applications of microbial fuel cells (MFCs) on large scale. Here, a novel nanoparticles of metal sheathed with metal oxide is electrodeposited on carbon paper (CP) to introduce as high-performance anodes of microbial fuel cell (MFC). This thin layer of metal/metal oxide significantly enhance the microbial adhesion, the wettability of the anode surface and decrease the electron transfer resistance. The investigation of the modified CP anodes in an air-cathode MFCs fed by various biocatalyst cultures shows a significant improving in the MFC performance. Where, the generated power and current density was 140% and 210% higher as compared to the pristine CP. Mixed culture of exoelectrogenic microorganism in wastewater exhibited good performance and generated higher power and current density compared to yeast as pure culture. The excellent capacitance with a distinctive nanostructure morphology of the modified-CP open an avenues for practical applications of MFCs. 相似文献
99.
In the present study, NiO and Cu-doped NiO nanoparticles were successfully synthesized by wet chemical method at room temperature using sodium hydroxide (NaOH) as precipitating agent. The as-prepared Cu-doped NiO powder samples were subjected to three different calcination temperatures such as, 350 °C, 450 °C and 550 °C in order to investigate the impact of calcined temperatures on the phase formation, particle size and band gap evolution. The phase formation and crystal structure information of the prepared nanomaterials were examined by X-ray powder diffraction (XRD). XRD revealed the face-centered cubic (FCC) structure. Average crystalline size of pure and doped samples estimated using Scherer formula was found to be 15 nm and 9 nm respectively. With increase in the calcination temperature from 350 °C to 550 °C for the Cu doped NiO samples the particle size of the nanoparticles was found to increase from 4 nm to 9 nm respectively. The optical study for both pure and doped NiO nanoparticles was performed using an UV–Vis spectrophotometer in the wavelength range of 200–800 nm. The strong absorption in the UV region confirms the band gap absorption in NiO and was estimated from the UV–Vis diffuse reflectance spectra via Tauc plot. Systematic studies were also carried out to study the effect of calcination on the optical transmittance. Samples were also investigated using Raman and Fourier Transform Infrared Spectroscopy (FTIR). Furthermore, morphology of the pure NiO and Cu-doped NiO Nanoparticles were examined by scanning electron microscope (SEM). 相似文献
100.
A precise control of the morphology and crystallization of perovskite thin-films is well-correlated to higher perovskite solar cells performances. Ionic liquids (ILs) can retard perovskite crystallization to aid the formation of films with uniform morphology to realize highly efficient perovskite solar cells. Herein, we attempt to control the nanostructural growth of CH3NH3PbI3 thin films by adding ILs to the perovskite spin-coating solution and investigate the effect of IL viscosity on the resulting CH3NH3PbI3 nanoparticle (NP) thin films. NPs with desirable morphology were obtained using ILs with a low viscosity that completely dissolved in the CH3NH3PbI3 solution. In particular, the IL tetrabutylammonium chloride yielded NPs with a diameter of 500 nm and controllable morphology, crystallinity, and absorption behavior, which led to improved photovoltaic performance compared with that of solar cells containing NPs produced using other ILs. Our findings revealed a pathway to obtain uniformly distributed CH3NH3PbI3 NP thin films for use in perovskite solar cells. The developed method is well suited for large-scale production of perovskite thin films on flexible substrates. 相似文献