| 1. |
- Allali, Naoual, et al.
(författare)
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Accurate control of the covalent functionalization of single-walled carbon nanotubes for the electro-enzymatically controlled oxidation of biomolecules
- 2018
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Ingår i: Beilstein Journal of Nanotechnology. - : Beilstein-Institut. - 2190-4286. ; 9, s. 2750-2762
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Tidskriftsartikel (refereegranskat)abstract
- Single-walled carbon nanotubes (SWCNTs) were functionalized by ferrocene through ethyleneglycol chains of different lengths (FcETGn) and the functionalized SWCNTs (f-SWCNTs) were characterized by different complementary analytical techniques. In particular, high-resolution scanning electron transmission microscopy (HRSTEM) and electron energy loss spectroscopy (EELS) analyses support that the outer tubes of the carbon-nanotube bundles were covalently grafted with FcETGn groups. This result confirms that the electrocatalytic effect observed during the oxidation of the reduced form of nicotinamide adenine dinucleotide (NADH) co-factor by the f-SWCNTs is due to the presence of grafted ferrocene derivatives playing the role of a mediator. This work clearly proves that residual impurities present in our SWCNT sample (below 5 wt. %) play no role in the electrocatalytic oxidation of NADH. Moreover, molecular dynamic simulations confirm the essential role of the PEG linker in the efficiency of the bioelectrochemical device in water, due to the favorable interaction between the ETG units and water molecules that prevents π-stacking of the ferrocene unit on the surface of the CNTs. This system can be applied to biosensing, as exemplified for glucose detection. The well-controlled and well-characterized functionalization of essentially clean SWCNTs enabled us to establish the maximum level of impurity content, below which the f-SWCNT intrinsic electrochemical activity is not jeopardized.
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| 2. |
- Allali, Naoual, et al.
(författare)
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Covalent functionalization of few-wall carbon nanotubes by ferrocene derivatives for bioelectrochemical devices
- 2012
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Ingår i: Physica status solidi. B, Basic research. - : Wiley. - 0370-1972 .- 1521-3951. ; 249:12, s. 2349-2352
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Tidskriftsartikel (refereegranskat)abstract
- The present work reports the covalent functionalization of few-wall CNTs (FWCNTs) by ferrocene derivatives to (i) improve their dispersion efficiency in water and (ii) graft electroactive chemical groups on their side-walls in order to promote electron transfer to biomolecules. The functionalized CNTs (f-CNTs) are used to modify a glassy carbon electrode and this modified electrode is used for oxidizing the cofactor NADH (dihydronicotinamide adenine dinucleotide).
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| 3. |
- Allali, Naoual, et al.
(författare)
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Electrocatalytic effect towards NADH induced by HiPco single-walled carbon nanotubes covalently functionalized by ferrocene derivatives
- 2013
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Ingår i: 2012 MRS Fall Meeting. - : Cambridge University Press.
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Konferensbidrag (refereegranskat)abstract
- The present work reports the covalent functionalization of single-walled carbon nanotubes (SWCNTs) by ferrocene derivatives with polyethyleneglycol linkers. A very clean initial sample was chosen to avoid any residual catalyst and carbon impurities. Functionalized SWCNTs (f-CNTs) are deposited on the surface of a glassy carbon electrode (GCE) and this modified electrode is used for oxidizing the cofactor NADH (dihydronicotinamide adenine dinucleotide) in the presence of diaphorase. A clear electrocatalytic effect is evidenced, which can only be attributed to the f-CNTs.
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| 4. |
- Allali, Naoual, et al.
(författare)
-
Few-wall carbon nanotubes covalently functionalized by ferrocene groups for bioelectrochemical devices
- 2012
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Ingår i: MRS Online Proceedings Library. - : Cambridge University Press. - 9781605114286
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Konferensbidrag (refereegranskat)abstract
- The present work reports the covalent functionalization of few-wall CNTs (FWCNTs) by ferrocene derivatives to i) improve their dispersion efficiency in water and ii) to graft electroactive chemical groups on their side-walls in order to promote electron transfer to biomolecules. The functionalized CNTs (f-CNTs) are used to modify a glassy carbon electrode and this modified electrode is used for oxidizing the cofactor NADH (dihydronicotinamide adenine dinucleotide).
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| 5. |
- Andersson, Odd E., et al.
(författare)
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A study of temperature and pressure induced structural and electronic changes in SbCl5 intercalated graphite : Part II. Experimental data for c-axis resistivity
- 1992
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Ingår i: Journal of Materials Research. - 0884-2914 .- 2044-5326. ; 7:11, s. 2989-3000
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Tidskriftsartikel (refereegranskat)abstract
- We present experimental data for the c-axis resistivity ?c of stage s = 2, 3, 4, 5, and 8, SbCl5 intercalated graphite, over the temperature range 40 to 300 K and the pressure range 0 to 0.8 GPa (0–8 kbar). For most specimens studied, resistance anomalies are observed below 230 K at atmospheric pressure and at pressures up to 0.5 GPa at 293 K. These anomalies are explained in terms of structural changes from a disordered or partly crystallized in-plane intercalate structure at atmospheric pressure and T > 230 K to an almost completely crystallized structure below this temperature, or at elevated pressures, as discussed in a companion paper. In the crystallized phases ?c is approximately linear in T except for stage 8, for which a nonlinear behavior, with a negative temperature coefficient of resistivity below 200 K, is observed. The results are compared with previously available literature data, and the p-T phase diagram is briefly discussed.
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| 6. |
- Andersson, Odd E., et al.
(författare)
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A study of temperature and pressure induced structural and electronic changes in SbCl5 intercalated graphite : Part IV: Basal plane resistivity
- 1995
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Ingår i: Journal of Materials Research. - 0884-2914 .- 2044-5326. ; 10:7, s. 1653-1660
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Tidskriftsartikel (refereegranskat)abstract
- Using an inductive technique, we have measured the in-plane resistivity rhoa of stages 2, 4, 5, and 8 SbCl5-GIC's versus temperature T and pressure p in the ranges 130–300 K and 0–0.85 GPa. The room temperature values of rhoa range from 4.0 µOcm for the stages 5 sample to 7.7 µOcm for the stage 8 sample. At all pressures, rhoa shows a metallic temperature dependence rhoa ~ Ta, with 1 < a < 2, but in contrast to the c-axis resistivity rhoc, it depends only very weakly on pressure and/or intercalate structural order. We show that the behavior observed is consistent with a band conduction model.
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| 7. |
- Andersson, Odd E., et al.
(författare)
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Pressure-induced modifications of structural and transport properties in SbCl5 intercalated graphite
- 1992
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Ingår i: Materials Science Forum volumes 91-93, Part I. - Zürich : Trans Tech Publications. - 0878496394 ; , s. 301-306
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Konferensbidrag (refereegranskat)abstract
- The structure and the c-axis resistivity of SbCl5 intercalated graphite have been studied as functions of T and p, over the ranges 40 to 295 K and 0 to 0.7 GPa. Slow cooling or slow application of pressure p > 0.4 GPa lead to states of complete but different crystallization of the intercalate, but after rapid cooling or pressurization any crystallization is incomplete. The resistivity of the high pressure crystallized phase is about 50% lower than that of the low T, low p phase under identical p-T conditions. No significant difference is seen between the behaviour of HOPG-based and single crystal based materials.
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| 8. |
- Andersson, Odd E., et al.
(författare)
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Structure, c-axis resistivity, and p-T phase diagram of SbCl5 intercalated graphite
- 1989
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Ingår i: Synthetic Metals volume 34. - Lausanne : Elsevier Sequoia SA. ; , s. 187-192
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Konferensbidrag (refereegranskat)abstract
- Experimental data are reported for the c-axis resistivity varrhoc of stages n = 3,4,5 and 8 SbCl5 intercalated graphite as a function of T and p, in the range 40 – 300 K and 0-0.5 GPa (5 kbar). varrhoc varied in a systematic way with p, T, and n. Well ordered low-T phases were obtained for all stages; disordering at 200 – 235 K gave rise to well defined multiple anomalies in varrhoc. We also report x-ray diffraction data on the stage 2 compound: evidence was found for large variations in the in-plane structure even for nominally identical samples.
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| 9. |
- Andersson, Odd E., et al.
(författare)
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The c-axis resistivity for two HOPG-based, first stage CuAl2Cl8 and second stage CuCl2 - graphite intercalation compounds as a function of both pressure and temperature
- 1996
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Ingår i: Journal of Physics and Chemistry of Solids, volume 57, issues 6-8. - : Elsevier Ltd.. ; , s. 719-723
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Konferensbidrag (refereegranskat)abstract
- In this paper we present data for the c-axis resistivity of first stage CuAl2Cl8 GIC and second stage CuCl2 GIC as functions of pressure, p, (0.0 < p < 1.5 GPa) and of temperature, T, (4 < T < 300 K). We show evidence of a possible new high-pressure phase above 1.0 GPa for the CuAl2Cl8 GIC and we show that the CuCl2 GIC is very stable at all pressures and temperature investigated. We make a comparison with previous results on SbCl5 GICs and other chloride intercalation compounds and with theories treating the temperature and pressure coefficients of transport parameters in layered solids.
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| 10. |
- Celzard, Alain, et al.
(författare)
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Conduction mechanisms in some graphite-polymer composites: effects of temperature and pressure
- 1998
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Ingår i: Journal of Applied Physics. - : American Institute of Physics. - 0021-8979 .- 1089-7550. ; 83:3, s. 1410-1419
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Tidskriftsartikel (refereegranskat)abstract
- This article is devoted to the conduction mechanisms involved in some highly electrically anisotropic resin–graphite particle composites. These materials are known to show a percolation phenomenon as the filler content is varied; they are epoxy or polyurethane based, the conducting particles are oriented single-crystal platelets, and samples are in the form of thick films. Because of their strong anisotropy, two types of measurements were made, i.e., parallel to and perpendicular to the plane of the films. Study of the resistivity variations of samples containing various concentrations in conducting particles was carried out first as a function of temperature from 4.2 to 300 K at ambient pressure, and second as a function of hydrostatic pressure up to 1.2 GPa, at room temperature. As the temperature is varied, the changes in resistivity of all the samples studied (i.e., above percolation threshold) are weak; analysis leads to the conclusion that thermally activated tunneling plays a dominant role above but close to the percolation threshold phic. As a function of pressure, more samples were studied: when the filler content is above phic, resistivity changes are quantitatively in agreement with what is expected from both percolation theory and tunneling; below threshold, the observed behavior is partially attributable to an ionic conduction mechanism throughout the polymer.
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