Raman validity for crystallite size La determination on reticulated vitreous carbon with different graphitization index

Baldan, Maurício Ribeiro; Almeida, E.C.; Azevedo, A.F.; Gonçalves, Emerson Sarmento; Rezende, Mirabel Cerqueira; Ferreira, N.G.

doi:10.1016/j.apsusc.2007.06.038

Cited by 69 publications

(32 citation statements)

References 14 publications

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“…The increase in the ratio I(D)/I(G) indicates a decrease in average crystallite size [28], even so at higher temperature anneals should lead to higher degree of grapitisation [16,30]. This increase in the I(D)/I(G) ratio for anneal for temperatures below 1000 °C has been reported before [31] and it has been suggested that the relation of the I(D)/I(G) ratio to crystallite size is not valid here [32]. However, it should be noted that the D band only stems from graphitic structures and there for very small graphitic flakes (~2 nm) in their embryonic state the I(D)/I(G) ratio increases [29].…”

Section: Resultsmentioning

confidence: 56%

Transparent ultrathin conducting carbon films

Schreiber

Lutz

Keeley

et al. 2010

Applied Surface Science

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Ultrathin conductive carbon layers (UCCLs) were created by spin coating resists and subsequently converting them to conductive films by pyrolysis. Homogeneous layers as thin as 3nm with nearly atomically smooth surfaces could be obtained. Layer characterization was carried out with the help of atomic force microscopy, profilometry, four-point probe measurements, Raman spectroscopy and ultraviolet-visible spectroscopy. The Raman spectra and high-resolution transmission electron microscopy image indicated that a glassy carbon like material was obtained after pyrolysis. The electrical properties of the UCCL could be controlled over a wide range by varying the pyrolysis temperature. Variation in transmittance with conductivity was investigated for applications as transparent conducting films. It was observed that the layers are continuous down to a thickness below 10 nm, with conductivities of 1.6 x 10 4 S/m, matching the best values observed for pyrolysed carbon films. Further, the chemical stability of the films and their utilization as transparent electrochemical electrodes has been investigated using cyclic voltammetry and electrochemical impedance spectroscopy.

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Section: Resultsmentioning

confidence: 56%

Transparent ultrathin conducting carbon films

Schreiber

Lutz

Keeley

et al. 2010

Applied Surface Science

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“…The integrated intensity ratio of the D and G bands, R= I D /I G , of many crystalline graphitic materials has been shown to be inversely proportional to the in-plane crystallite sizes L a obtained from the analysis of X-ray diffraction peaks of such materials (L a ≈ R −1 ) 55. Based on the data in Figure 4, the ratio R for the original, water-boiled, and acid-microwaved CNT was equal to 0.68, 0.76, and 1.5, respectively.…”

Section: Resultsmentioning

confidence: 99%

Facilitation of NADH Electro-oxidation at Treated Carbon Nanotubes

2010

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The relationship between the state of the surface of carbon nanotubes (CNT) and their electrochemical activity was investigated using the enzyme cofactor dihydronicotinamide adenine dinucleotide (NADH) as a redox probe. The boiling of CNT in water, while nondestructive, activated them toward the oxidation of NADH as indicated by a shift in the anodic peak potential of NADH (E NADH ) from 0.4 to 0.0 V. The shift in E NADH was due to the redox mediation of NADH oxidation by traces of quinone species that were formed on the surface of treated CNT. The harsher treatment that comprised of microwaving of CNT in concentrated nitric acid had a similar effect on the E NADH and, additionally, it increased the anodic peak current of NADH. The latter correlated with the formation of defects on the surface of acid-microwaved CNT as indicated by their Raman spectra. The increase in current was discussed considering a role of surface mediators on the buckled graphene sheets of acid-microwaved CNT. The other carbon allotropes including the edge plane pyrolytic graphite, graphite powder, and glassy carbon did not display a comparable activation toward the oxidation of NADH.

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“…It has been shown that Raman spectroscopy can be utilized to gain information on the structural order of carbonaceous materials (Angoni et al, 1992;Baldan et al, 2007;Bernard et al, 2010;Beyssac et al, 2002Beyssac et al, , 2003Bustin et al, 1995;Cuesta et al, 1994;Ferrari, 2007;Ferrari and Robertson, 2000;Johnson et al, 1986;Lahfid et al, 2010;Liu et al, 2013;Nakamizo et al, 1974;Rodrigues et al, 2013;Sadezky et al, 2005;Tuinstra and Koenig, 1970;Zaida et al, 2007). The history of different approaches to coal analysis with Raman spectroscopy has been reviewed by Potgieter-Vermaak et al (2011).…”

Section: Introductionmentioning

confidence: 98%