Electromagnetic properties of inner double walled carbon nanotubes investigated by nuclear magnetic resonance
Name:
Article-Journal_of-Electromag-2013.pdf
Size:
2.228Mb
Format:
PDF
Description:
Article - Full Text
Type
Article
KAUST Department
KAUST Catalysis Center (KCC)Date
2013Permanent link to this record
http://hdl.handle.net/10754/334524Metadata
Show full item recordAbstract
The nuclear magnetic resonance (NMR) analytical technique was used to investigate the double walled carbon nanotubes (DWNTs) electromagnetic properties of inner walls. The local magnetic and electronic properties of inner nanotubes in DWNTs were analyzed using 25% 13C enriched C 60 by which the effect of dipolar coupling could be minimized. The diamagnetic shielding was determined due to the ring currents on outer nanotubes in DWNTs. The NMR chemical shift anisotropy (CSA) spectra and spin-lattice relaxation studies reveal the metallic properties of the inner nanotubes with a signature of the spin-gap opening below 70 K.Citation
Bouhrara M, Abou-Hamad E, Alabedi G, Al-Taie I, Kim Y, et al. (2013) Electromagnetic Properties of Inner Double Walled Carbon Nanotubes Investigated by Nuclear Magnetic Resonance. Journal of Nanomaterials 2013: 1-6. doi:10.1155/2013/713475.Publisher
Hindawi LimitedJournal
Journal of NanomaterialsScopus Count
The following license files are associated with this item:
Except where otherwise noted, this item's license is described as This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Related items
Showing items related by title, author, creator and subject.
-
Effect of membrane property and operating conditions on phytochemical properties and permeate flux during clarification of pineapple juice(Journal of Food Engineering, Elsevier BV, 2010-10) [Article]The effects of membrane property on the permeate flux, membrane fouling and quality of clarified pineapple juice were studied. Both microfiltration (membrane pore size of 0.1 and 0.2 μm) and ultrafiltration (membrane molecular weight cut-off (MWCO) of 30 and 100 kDa) membranes were employed. Membrane filtration did not have significant effects on the pH, reducing sugar and acidity of clarified juice whereas the suspended solids and microorganism were completely removed. The 0.2 μm membrane gave the highest permeate flux, total vitamin C content, total phenolic content and antioxidant capacity as well as the highest value of irreversible fouling. Based on these results, the membrane with pore size of 0.2 μm was considered to be the most suitable membrane for the clarification of pineapple juice. The optimum operating conditions for the clarification pineapple juice by membrane filtration was a cross-flow velocity of 3.4 ms-1 and transmembrane pressure (TMP) of 0.7 bar. An average flux of about 37 lm-2 h-1 was obtained during the microfiltration of pineapple juice under the optimum conditions using batch concentration mode. © 2010 Elsevier Ltd. All rights reserved.
-
Structure-Property Relationships of Polyimides with Intrinsic Microporosity (PIM-PIs) and Their Gas Transport Properties(2019-04) [Dissertation]
Advisor: Pinnau, Ingo
Committee members: Mohammed, Omar F.; Han, Yu; Xia, YanPolymers with intrinsic microporosity (PIMs) showed the potential to provide highly permeable and highly selective membranes for gas separation applications with the ability to fine-tune their properties for better performance. The concept of microporosity was extended to the polyimides by using kinked, contorted and stable structures to obtain high gas performance combined with excellent solution-processability, high thermal stability, and a unique platform for a wide range of possible modifications and tunability. Thus, studying the structure-property relationships is a critical key to develop advanced materials that can replace the commercially available membranes like cellulose acetate and Matrimid. Importantly, in the microporous polyimides (PIM-PIs) system, varying the type of the side chains appended to the diamines or dianhydrides impacts polymeric membrane properties, and in turn, gas separation performance. In this dissertation, we have examined the effect of ring substitutes, incorporated into novel polyimides backbones, on polymer properties and gas separation performance. The choice of side group can induce subtle changes in material properties and molecular interactions between the polymeric chains and affect the pore-size distribution, chain packing and yielding distinct combination between gas permeability and permselectivity. We have shown that the effect of tertiary amine groups, in polyimide structures, on the CO2 solubility is marginal but it can control the chain packing. However, introducing bromine groups on the polymer backbone can boost the O2 permeability and O2/N2 selectivity and perform better than the commercially available membranes. BCBr4-SBIDA demonstrated the same O2/N2 selectivity relative to cellulose acetate but approximately 10-fold higher gas permeability. Combining high selectivity with good permeability was achieved by a newly designed carboxyl-functionalized homopolymer (6FDA-TrMPD) with CO2 permeability of 144 barrer and CO2/CH4 selectivity of 45. The new W-shaped CANAL diamines, prepared by one-step synthesis, were used as microporosity generators in polyimides and revealed promising gas transport performance with the same selectivity relative to cellulose acetate by 23-fold higher permeability (CANAL-PI-3-MeNH2). Therefore, developing advanced polymers for membrane-based gas separation can be obtained by an ideal combination between kinked monomers, side chains, and stable materials. -
Photo/Electrocatalytic Properties of Nanocrystalline ZnO and La-Doped ZnO: Combined DFT Fundamental Semiconducting Properties and Experimental Study(ChemistrySelect, Wiley, 2018-07-18) [Article]This work reports the synthesis of nanocrystalline ZnO and 5% La-doped ZnO (La/ZnO) materials for photo/electrocatalytic degradation of Rhodamine B. The samples were characterized by X-Ray diffraction, scanning and transmission electron microscopy, X-Ray photoelectron spectroscopy and diffuse reflectance spectra. The effect of La doping on electronic structure was investigated using density functional theory calculations (DFT), La-doped ZnO showed an n-type metallic nature compared to pristine ZnO and La doping creates occupied states within the band gap edge. Under UV light, La/ZnO showed higher kinetic constant and efficiency than ZnO. A possible mechanism was elaborated on the basis of DFT and active trapping measurements. Different initial Rhodamine B concentration were studied to assess the electro-oxidation of RhB. The electrochemical degradation of RhB over La/ZnO spindles electrode was pronounced with three time's high kinetic constant. The superior electro/photoactivity of La/ZnO was due to its unique morphology, high charge separation of the charge carriers and higher conductivity induced by La-doping (intermediary levels). Superoxide ions and holes were the main active species for the photodegradation. Whereas, synergetic effect of hydroxyl radicals and hypochlorite ions were responsible of the high RhB electrocatalytic degradation.
