Laser power influence on Raman spectra of multilayer graphene, multilayer graphene oxide and reduced multilayer graphene oxide

Ferreira, Henrique; Poma, G; Acosta, Dwight; Barzola‐Quiquia, J.; Quintana, María; Barreto, Lucas; Champi, A.

doi:10.1088/1742-6596/1143/1/012020

Cited by 6 publications

(4 citation statements)

References 21 publications

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“…The response of rGO sample was similar to the unannealed hdG sample and showed almost no dependence on the laser power. Contrary to us, Ferreira et al [77] observed a decrease in D/G band ratio with increasing power, λ L = 532 nm, in the range from 0.5 to 3 mW in samples of multilayer graphene oxide (MLGO) and reduced MLGO. These materials also exhibited the shift of G band position and increase of its FWHM with increasing laser power, while mechanically exfoliated multilayer graphene showed no such dependence.…”

Section: Fingerprint Behavior Of Gsg Nanosheets During High Laser Pow...contrasting

confidence: 61%

Controlled high temperature stability of microwave plasma synthesized graphene nanosheets

Jašek¹,

Toman²,

Všianský³

et al. 2021

J. Phys. D: Appl. Phys.

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High temperature stability of nanomaterials plays an important role for their application in the field of nanocomposites, batteries, and sensors. Few-layer graphene nanosheets prepared by microwave plasma based decomposition of ethanol exhibited high thermal stability in the oxidation atmosphere in dependence on controlled formation of structural disorder. Analysis of differential thermogravimetry (DTG) curve profile showed three temperature regions, around 345 °C, 570 °C and above 700 °C, related to amorphous phase with a carbon–oxygen functional groups, small defective nanostructures and highly crystalline structure of graphene nanosheets, respectively. Raman spectroscopy and x-ray photoelectron spectroscopy (XPS) analysis of the nanosheets showed an increase of D/G Raman band ratio as well as increasing of sp3 phase content, from 6.1 at% to 15.2 at%, for highly crystalline and highly disordered structure of the nanosheets. Thermal annealing under synthetic air was used to investigate the variation in D/G and 2D/G Raman band ratio of the samples and to estimate activation energy of oxidation and disintegration process of graphene nanosheets. The highest oxidation resistance exhibited sample with high 2D/G band ratio (1.54) and lowest oxygen content of 1.7 at%. The synthesis process led to stabilization of nanosheet structure by formation of curved edges and elimination of free dangling bonds. The nanosheets prepared in microwave plasma exhibited high surface area, over 350 m2 g−1, and superior thermal stability with defect activation energy in an oxidation atmosphere higher than 2 eV. Heat release rate during the oxidation process was in correlation with the amount of disorder in the samples. Fast and easy to use technique based on high power Raman spectroscopy was developed for assessment of nanomaterial oxidation resistance.

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Section: Fingerprint Behavior Of Gsg Nanosheets During High Laser Pow...contrasting

confidence: 61%

Controlled high temperature stability of microwave plasma synthesized graphene nanosheets

Jašek¹,

Toman²,

Všianský³

et al. 2021

J. Phys. D: Appl. Phys.

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“…Methylene blue (MB), also called methylthionine chloride, is an organic dye with the molecular formulation C 16 H 18 N 3 Cl 1 S 1 and a molecular weight of 319.85 g/mol. Its maximum absorbance is at 663 nm [ 54 ]. The absorbance analysis of the samples after exposure to UV light was performed in the range of 460–750 nm as shown in Figure 11 .…”

Section: Resultsmentioning

confidence: 99%

Eco-Friendly Reduction of Graphene Oxide by Aqueous Extracts for Photocatalysis Applications

et al. 2022

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In the present work, reduced graphene oxide was obtained by green synthesis, using extracts of Larrea tridentata (gobernadora) and Capsicum Chinense (habanero). Graphene oxide was synthesized by the modified Hummers’ method and subsequently reduced using natural extracts to obtain a stable and environmentally friendly graphene precursor. Consequently, the gobernadora aqueous extract was found to have a better reducing power than the habanero aqueous extract. This opportunity for green synthesis allows the application of RGO in photocatalysis for the degradation of the methylene blue dye. Degradation efficiencies of 60% and 90% were obtained with these materials.

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“…These two stages can be distinguished by looking at additional Raman parameters, such as the Γ of selected peaks, because the Γ increases for increasing defect concentration [38,39,41] and strain [42,43]. Directly comparing measurements between different instruments can also be challenging, as factors such as laser excitation energy [48,49], laser power [50], instrument calibration, microscope objectives [51], slit width and grating can affect Raman peak positions, peak widths and peak intensity ratios. An important example of this is the difference in the D peak position and intensity for the same graphene sample when using different excitation lasers, as it is strongly dispersive with excitation energy due to a Kohn Anomaly at K [48,[52][53][54].…”

Section: Introductionmentioning

confidence: 99%

International interlaboratory comparison of Raman spectroscopic analysis of CVD-grown graphene

Turner¹,

Paton²,

Legge³

et al. 2022

2D Mater.

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There is a pressing need for reliable, reproducible and accurate measurements of graphene’s properties, through international standards, to facilitate industrial growth. However, trustworthy and verified standards require rigorous metrological studies, determining, quantifying and reducing the sources of measurement uncertainty. Towards this effort, we report the procedure and the results of an international interlaboratory comparison (ILC) study, conducted under Versailles Project on Advanced Materials and Standards (VAMAS). This ILC focusses on the comparability of Raman spectroscopy measurements of chemical vapour deposition (CVD) grown graphene using the same measurement protocol across different institutes and laboratories. With data gathered from 17 participants across academia, industry (including instrument manufacturers) and national metrology institutes, this study investigates the measurement uncertainty contributions from both Raman spectroscopy measurements and data analysis procedures, as well as provides solutions for improved accuracy and precision. While many of the reported Raman metrics were relatively consistent, significant and meaningful outliers occurred due to differences in the instruments and data analysis. These variations resulted in inconsistent reports of peak intensity ratios, peak widths and the coverage of graphene. Due to a lack of relative intensity calibration, the relative difference reported in the 2D- and G peak intensity ratios (Ι_2D/Ι_G) was up to 200%. It was also shown that the standard deviation for Γ_2D values reported by different software packages, was 15× larger for Lorentzian fit functions than for pseudo-Voigt functions. This study has shown that by adopting a relative intensity calibration and consistent peak fitting and data analysis methodologies, these large, and previously unquantified, variations can be significantly reduced, allowing more reproducible and comparable measurements for the graphene community, supporting fundamental research through to the growing graphene industry worldwide. This project and its findings directly underpin the development of the ISO/IEC standard “DTS 21356-2 - Nanotechnologies - Structural Characterisation of CVD-grown Graphene”.

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Laser power influence on Raman spectra of multilayer graphene, multilayer graphene oxide and reduced multilayer graphene oxide

Cited by 6 publications

References 21 publications

Controlled high temperature stability of microwave plasma synthesized graphene nanosheets

Controlled high temperature stability of microwave plasma synthesized graphene nanosheets

Eco-Friendly Reduction of Graphene Oxide by Aqueous Extracts for Photocatalysis Applications

International interlaboratory comparison of Raman spectroscopic analysis of CVD-grown graphene

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