Flipping growth orientation of nanographitic structures by plasma enhanced chemical vapor deposition

Ghosh, Subrata; Ganesan, K.; Polaki, S. R.; Ilango, S.; Amirthapandian, S.; Dhara, Sandip; Kamruddin, M.; Tyagi, A.K.

doi:10.1039/c5ra20820c

Cited by 22 publications

(25 citation statements)

References 38 publications

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“…However, the plasma chemistry and chemical reactions with the substrate surface during growth are still a matter of study [ 9 , 27 – 50 ]. The role of gas composition, deposition time and nature of substrate on the growth of VGNs has been discussed [ 24 , 27 , 47 ]. The first two parameters underpin the two competing disorder-related mechanisms.…”

Section: Introductionmentioning

confidence: 99%

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Process-specific mechanisms of vertically oriented graphene growth in plasmas

Ghosh¹,

Polaki²,

Kumar³

et al. 2017

Beilstein J. Nanotechnol.

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Applications of plasma-produced vertically oriented graphene nanosheets (VGNs) rely on their unique structure and morphology, which can be tuned by the process parameters to understand the growth mechanism. Here, we report on the effect of the key process parameters such as deposition temperature, discharge power and distance from plasma source to substrate on the catalyst-free growth of VGNs in microwave plasmas. A direct evidence for the initiation of vertical growth through nanoscale graphitic islands is obtained from the temperature-dependent growth rates where the activation energy is found to be as low as 0.57 eV. It is shown that the growth rate and the structural quality of the films could be enhanced by (a) increasing the substrate temperature, (b) decreasing the distance between the microwave plasma source and the substrate, and (c) increasing the discharge power. The correlation between the wetting characteristics, morphology and structural quality is established. It is also demonstrated that morphology, crystallinity, wettability and sheet resistance of the VGNs can be varied while maintaining the same sp3 content in the film. The effects of the substrate temperature and the electric field in vertical alignment of the graphene sheets are reported. These findings help to develop and optimize the process conditions to produce VGNs tailored for applications including sensing, field emission, catalysis and energy storage.

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Section: Introductionmentioning

confidence: 99%

“…The first two parameters underpin the two competing disorder-related mechanisms. These mechanisms contribute to the defect band intensity through graphite structure amorphization and growth orientation [ 27 , 47 ].…”

Section: Introductionmentioning

confidence: 99%

Process-specific mechanisms of vertically oriented graphene growth in plasmas

Ghosh¹,

Polaki²,

Kumar³

et al. 2017

Beilstein J. Nanotechnol.

Self Cite

View full text Add to dashboard Cite

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“…So, the I D /I G ratio could not be appropriated to show the impact of the reduction process. Instead, the full width at half maximum (FWHM) of the G band may be considered, as it does not vary significantly at the edges [ 45 , 46 ]. A continuous increase of the FWHM of the G band with the increase in CA amount was observed in the reduced samples, shown in Figure 5 c, from 49.3 cm −1 for GO:CA (1:0) sample to 62.0 cm −1 , 63.9 cm −1 and 66.8 cm −1 for GO:CA (1:0.1), GO:CA (1:0.5) and GO:CA (1:1) samples, respectively.…”

Section: Resultsmentioning

confidence: 99%

Joining Caffeic Acid and Hydrothermal Treatment to Produce Environmentally Benign Highly Reduced Graphene Oxide

et al. 2021

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Reduced graphene oxide (rGO) is a promising graphene-based material, with transversal applicability to a wide range of technological fields. Nevertheless, the common use of efficient—but hazardous to environment and toxic—reducing agents prevents its application in biological and other fields. Consequently, the development of green reducing strategies is a requirement to overcome this issue. Herein, a green, simple, and cost-effective one-step reduction methodology is presented. Graphene oxide (GO) was hydrothermally reduced in the presence of caffeic acid (CA), a natural occurring phenolic compound. The improvement of the hydrothermal reduction through the presence of CA is confirmed by XRD, Raman, XPS and TGA analysis. Moreover, CA polymerizes under hydrothermal conditions with the formation of spherical and non-spherical carbon particles, which can be useful for further rGO functionalization. FTIR and XPS confirm the oxygen removal in the reduced samples. The high-resolution scanning transmission electron microscopy (HRSTEM) images also support the reduction, showing rGO samples with an ordered graphitic layered structure. The promising rGO synthesized by this eco-friendly methodology can be explored for many applications.

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“…Further details are reported in ref. 46 and 47. The deposition targetsubstrates are placed between 10, 20, 30 and 40 cm below the plasma source, resulting in the samples named V 1 Graphene, V 2 -Graphene, V 3 Graphene and V 4 Graphene respectively; and consequently in VGs of different structures in terms of height and density/spacing.…”

Section: Methodsmentioning

confidence: 99%