Evolution of large-area reduced graphene oxide nanosheets from carbon dots via thermal treatment

Mokoloko, Lerato L.; Matsoso, Boitumelo J.; Forbes, Roy P.; Barrett, Dean H.; Moreno, Beatriz; Coville, Neil J.

doi:10.1016/j.cartre.2021.100074

Cited by 20 publications

(20 citation statements)

References 79 publications

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“…The lack of the low temperature peak(s) for the NCDs700 sample is indicative of the formation of a CDs-free product. 22 More importantly, the peak at ca. 500 °C for NCDs400 and the broadness of peaks for the NCDs700 samples can be linked to strongly bound functional groups.…”

Section: Resultsmentioning

confidence: 99%

From 0D to 2D: N-doped carbon nanosheets for detection of alcohol-based chemical vapours

et al. 2022

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Section: Resultsmentioning

confidence: 99%

From 0D to 2D: N-doped carbon nanosheets for detection of alcohol-based chemical vapours

et al. 2022

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“…These CDs were classified as CQDs and had average particle sizes ranging between 1 and 4 nm. These CQDs were then annealed at 200–700 °C for 10 min [ 117 ]. Carbon chunks similar to those observed by Hou et al [ 116 ] were observed at 250 °C.…”

Section: Synthesis Of Larger Carbon Allotropesmentioning

confidence: 99%

“…The CD assembly process appears to be highly dependent on the reduction or removal of surface functional groups, especially in a deoxygenation process. This reduction or removal leads to an increase in the C species, which then react to form C-C bonds and the larger carbon allotropes [ 17 , 117 ]. The XPS analysis results are usually used to confirm the functional group’s removal or transformation.…”

Section: Mechanism Of Formation Of the Dimensional Carbon Allotropes ...mentioning

confidence: 99%

“…Thus, the study by Hou et al showed that both the temperature and metal catalyst were needed for the transformation of CDs to larger carbon allotropes [ 17 , 116 ]. However, other studies showed that only thermal procedures were needed to convert CDs and N-doped CDs to graphene nanosheets [ 117 , 136 ], while Bharathi et al formed layered sheets by varying only the catalyst concentration [ 118 ]. In contrast, the synthesis of supra-CD studies suggested that the CDs can assemble spontaneously [ 129 ] merely by adding them to a solvent [ 128 , 130 ]; however, these are not permanent structures.…”

Section: Mechanism Of Formation Of the Dimensional Carbon Allotropes ...mentioning

confidence: 99%

“… Schematic representation of the synthesis procedure and TEM images of the resulting product formed during the conversion of 0-D CDs to 2-D graphene-like nanosheets using a ( a , b ) high-temperature (> 300 °C) treatment without a catalyst (reproduced with permission from [ 117 ], copyright 2021, Elsevier BV) and ( c , d ) lower-temperature (180 °C) treatment in the presence of a metal catalyst (reproduced with permission from [ 118 ], copyright 2017, Springer Nature). …”

Section: Figures Scheme and Tablementioning

confidence: 99%

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The Transformation of 0-D Carbon Dots into 1-, 2- and 3-D Carbon Allotropes: A Minireview

2022

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Carbon dots (CDs) represent a relatively new type of carbon allotrope with a 0-D structure and with nanoparticle sizes < 10 nm. A large number of research articles have been published on the synthesis, characteristics, mechanisms and applications of this carbon allotrope. Many of these articles have also shown that CDs can be synthesized from “bottom-up” and “top-down” methods. The “top-down” methods are dominated by the breaking down of large carbon structures such as fullerene, graphene, carbon black and carbon nanotubes into the CDs. What is less known is that CDs also have the potential to be used as carbon substrates for the synthesis of larger carbon structures such as 1-D carbon nanotubes, 2-D or 3-D graphene-based nanosheets and 3-D porous carbon frameworks. Herein, we present a review of the synthesis strategies used to convert the 0-D carbons into these higher-dimensional carbons. The methods involve the use of catalysts or thermal procedures to generate the larger structures. The surface functional groups on the CDs, typically containing nitrogen and oxygen, appear to be important in the process of creating the larger carbon structures that typically are formed via the generation of covalent bonds. The CD building blocks can also ‘aggregate’ to form so called supra-CDs. The mechanism for the formation of the structures made from CDs, the physical properties of the CDs and their applications (for example in energy devices and as reagents for use in medicinal fields) will also be discussed. We hope that this review will serve to provide valuable insights into this area of CD research and a novel viewpoint on the exploration of CDs.

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Hydrogenation of Cinnamaldehyde Using Carbon Dots Reduced Palladium Nanoparticles

Magubane,

Gangatharan,

Mente

et al. 2024

Catal Lett

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Carbon dots (CDs) with a size range of 0.2 to 2 nm were prepared using a hydrothermal treatment of sucrose and oleic acid. The as-synthesized CDs were used to reduce H2PdCl4 to metallic Pd nanoparticles with dPd = 9.3 ± 3.7 nm, as confirmed by PXRD and HRTEM data. Pd particles were made to be larger than the CDs, to observe any inverse support effects, however, TEM data revealed that the CDs were transformed to carbon sheets in the reduction reaction at 100 °C. The synthesized Pd-CDs catalysts (0.81 wt. % loading) and CDs were both tested for the liquid phase hydrogenation of cinnamaldehyde. The influence of mass, temperature, and hydrogen flow rate on the activity and selectivity of the CDs and Pd-CDs catalyst on the hydrogenation of cinnamaldehyde was investigated. The CDs gave a cinnamaldehyde conversion (40%, 4 h) with selectivity towards the reduction of the C = O bond (cinnamyl alcohol) while the Pd-carbon catalyst was only selective to the reduction of the C = C bond (conversion 78%) indicating the dominance of Pd in the reaction. Post analysis of the deactivated catalysts indicated formation of carbon sheets and sintering of the Pd nanoparticles. It is thus shown that the presence of Pd induces the CDs to carbon sheet formation and thus indicates the limited use of CDs as a support for the olefin hydrogenation reaction with the CDs produced carbon support. This finding has implications for other studies using CDs as supports. Graphical abstract

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Evolution of large-area reduced graphene oxide nanosheets from carbon dots via thermal treatment

Cited by 20 publications

References 79 publications

From 0D to 2D: N-doped carbon nanosheets for detection of alcohol-based chemical vapours

From 0D to 2D: N-doped carbon nanosheets for detection of alcohol-based chemical vapours

The Transformation of 0-D Carbon Dots into 1-, 2- and 3-D Carbon Allotropes: A Minireview

Hydrogenation of Cinnamaldehyde Using Carbon Dots Reduced Palladium Nanoparticles

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