Showing papers by "Malcolm L. H. Green published in 2009"
TL;DR: Conformal growth of PbI( 2) layers on the inner wall of the relatively wide WS(2) nanotubes leads to nanotubular structures which were not previously observed in narrow carbon nanotube templates.
Abstract: Multiwall WS(2) nanotube templates were used as hosts to prepare core-shell PbI(2)@WS(2) nanotubes by a capillary-wetting method. Conformal growth of PbI(2) layers on the inner wall of the relatively wide WS(2) nanotubes (i.d. ca. 10 nm) leads to nanotubular structures which were not previously observed in narrow carbon nanotube templates. Image simulation after structural modeling (see picture) showed good agreement with the experimental HRTEM image.
53 citations
TL;DR: In this paper, it is demonstrated that functionalization of single-wall carbon nanotubes can be carried out using simple chlorosilane chemistry, which allows coupling of the SWCNTs with external chemical species, such as organic polymers and magnetically iron oxide-in-silica nanoparticles.
35 citations
TL;DR: In this article, the authors present a methodology for the quantitative assessment of the amount of material encapsulated in filled carbon nanotubes, which is based on high-resolution transmission electron microscopy and X-ray electron dispersive spectroscopy experiments.
Abstract: In this paper, we present the first methodology for the quantitative assessment of the amount of material encapsulated in filled carbon nanotubes. Samples of single-walled carbon nanotubes have been filled by molten-phase capillary wetting with CuI, FeCl2, and CuBr. A suitable solvent has been used in each case to remove the large amount of external material present after the filling step. Thermogravimetric analyses in air have been performed to the empty and filled nanotubes, and the data have been used to obtain the filling yield for each sample. By using different starting nanotube samples, we stress the importance of the correct analysis of the data, which becomes more crucial for samples with larger quantities of metal catalyst impurities. High-resolution transmission electron microscopy and X-ray electron dispersive spectroscopy experiments confirm the encapsulation of the desired compounds into the single-walled carbon nanotubes and the absence of external metal halides. The method proposed herein ...
30 citations
TL;DR: Transport measurements reveal that the negative photocurrent in s (semiconducting)-SWNTs@ZnO could be described by electron-hole compensation behavior attributed to the ZnO layer under ultraviolet excitation, suggesting a clear photosensitization effect.
Abstract: Uniform zinc oxide coated single-walled nanotubes (SWNTs) were fabricated by ultrasonic irradiation with acid-treated SWNTs, zinc acetate, and triethanolamine at low temperature in aqueous phase processing The ZnO coating process did not decrease the dark current of the SWNTs, but a real decrease in the steady state negative photocurrent was observed after ZnO coating, suggesting a clear photosensitization effect Transport measurements reveal that the negative photocurrent in s (semiconducting)-SWNTs@ZnO could be described by electron-hole compensation behavior attributed to the ZnO layer under ultraviolet excitation This simple coating method for one-dimensional material can open up new possibilities for multifunctional nanodevices
29 citations
TL;DR: The catalytic activities for the rhodium(I) complexes 6a and 6b were evaluated for the hydroformylation of 1-octene and the base dependent decomposition of imidazolinium salts via ring opening at the backbone was observed.
Abstract: Stable annulated diaminocarbene ligands 7,9-bis(2,4,6-trimethylphenyl)-6b,9a-dihydroace naphtha[1,2-d]imidazolin-2-ylidene and 7,9-bis(2,6-diisopropylphenyl)-6b,9a-dihydroacenaphtho[1,2-d]imidazolin-2-ylidene; designated as (BIAN-SIMes, 5a,) and (BIAN-SIPr, 5b), respectively, have been prepared. The base dependent decomposition of imidazolinium salts via ring opening at the backbone was also observed. The corresponding rhodium(I) and iridum(I) complexes (η4-1,5-COD)M(BIAN-SIMes)Cl and (η4-1,5-COD)M(BIAN-SIPr)Cl; M= Rh (6a, 6b) and Ir (7a, 7b) have been synthesised by the reaction of free carbene with [M(η4-1,5-COD)(μ-Cl)]2; where M= Rh, Ir. The cationic Ir(I) complexes [(η4-1,5-COD)Ir(BIAN-SIMes)Py]BF48a and [(η4-1,5-COD)Ir(BIAN -SIPr)Py]PF68b have also been synthesised. Compounds 4b, 5a, 6a, 6b, 7b and 8b have been structurally characterised. The catalytic activities for the rhodium(I) complexes 6a and 6b were evaluated for the hydroformylation of 1-octene.
22 citations
TL;DR: The use of steam for the purification of SW NTs samples allows the removal of the amorphous carbon and graphitic layers coating the metal particles present in the sample without altering the tubular structure of the SWNTs.
Abstract: When a sample of as-made single-walled carbon nanotubes (SWNTs) is treated with nitric acid, oxidation debris are formed due to the functionalization (mainly carboxylation) of the amorphous carbon present in the sample and a continuous coating along the carbon nanotube walls is created preventing the sidewall functionalization of the SWNTs. This oxidation debris can be easily removed by an aqueous base wash leaving behind a sample with a low degree of functionality. After removal of the amorphous carbon (by steam purification) from a sample of as-made SWNTs, the resulting purified SWNTs are readily carboxylated on the walls by nitric acid treatment. The use of steam for the purification of SWNTs samples allows the removal of the amorphous carbon and graphitic layers coating the metal particles present in the sample without altering the tubular structure of the SWNTs. The exposed metal particles can then be easily removed by an acid wash. Comparison between the steam treatment and molten sodium hydroxide treatment is made.
12 citations
TL;DR: In this article, BaMn2Al10O19 is shown to be active and stable for the combustion reaction, with no carbon formation in the reactor and no carbide catalyst oxidation observed.
10 citations
Posted Content•
TL;DR: Carbon Nanoflakes (CNFs) as discussed by the authors are single, graphenic sheets containing a small number of internal defects, and the edges are decorated with primarily carboxylic acid groups which allow facile chemical functionalisation and cross-linking of the fragments using multivalent cations.
Abstract: Carbon Nanoflakes (CNFs) with average diameters of about 30 nm have been prepared and isolated in bulk quantities by a single-step oxidation procedure using single-wall carbon nanotube arc-discharge material and nitric acid. The CNFs are predominately single, graphenic sheets containing a small number of internal defects. The edges are decorated with primarily carboxylic acid groups which allow facile chemical functionalisation and cross-linking of the fragments using multivalent cations.
1 citations