The Role of Oxygen during Thermal Reduction of Graphene Oxide Studied by Infrared Absorption Spectroscopy

Açık, Müge; Lee, Geunsik; Mattevi, Cecilia; Pirkle, Adam; Wallace, Robert M.; Chhowalla, Manish; Cho, Kyeongjae; Chabal, Yves J.

doi:10.1021/jp2052618

Cited by 794 publications

(641 citation statements)

References 129 publications

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“…3e,f). As previously reported, 39 infrared spectra of as-synthesized GO indicate contributions from various oxygen functional groups. These groups include contributions from hydroxyls (C-OH for phenols or lactols at B3,000-3,600 and B1,050-1,150 cm À 1 ), carbonyls (C ¼ O, generalized for ketonic edge groups such as anhydrides, lactones and pyrones at B1,500-1,850 cm À 1 ), carboxyls (COOH (Fig.…”

Section: Resultssupporting

confidence: 77%

Probing the catalytic activity of porous graphene oxide and the origin of this behaviour

et al. 2012

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Graphene oxide, a two-dimensional aromatic scaffold decorated by oxygen-containing functional groups, possesses rich chemical properties and may present a green alternative to precious metal catalysts. Graphene oxide-based carbocatalysis has recently been demonstrated for aerobic oxidative reactions. However, its widespread application is hindered by the need for high catalyst loadings. Here we report a simple chemical treatment that can create and enlarge the defects in graphene oxide and impart on it enhanced catalytic activities for the oxidative coupling of amines to imines (up to 98% yield at 5 wt% catalyst loading, under solvent-free, open-air conditions). This study examines the origin of the enhanced catalytic activity, which can be linked to the synergistic effect of carboxylic acid groups and unpaired electrons at the edge defects. The discovery of a simple chemical processing step to synthesize highly active graphene oxide allows the premise of industrial-scale carbocatalysis to be explored.

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Section: Resultssupporting

confidence: 77%

Probing the catalytic activity of porous graphene oxide and the origin of this behaviour

et al. 2012

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“…Strong peaks attributed to the characteristic vibrational modes of oxygen functional groups (-OH at 3434 cm − 1 , C = O at 1725 cm − 1 , C-O in 1024-1180 cm − 1 and C-O-C at 1200 cm − 1 ) could be clearly observed in the spectra of the GQDs, whereas the peak at 1629 cm − 1 resulted from sp 2 -hybridized C = C bonds (in-plane stretching). 27 Characterization of the GQDs-S composite. The SEM and TEM images in Figure 1d and e show the morphology of the GQDs-S. Sulfur particles measuring several microns were homogeneously coated with GQDs.…”

Section: Methodsmentioning

confidence: 99%

Graphene quantum dots: structural integrity and oxygen functional groups for high sulfur/sulfide utilization in lithium sulfur batteries

et al. 2016

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Lithium-sulfur (Li-S) batteries are expected to overcome the limit of current energy storage devices by delivering high specific energy with low material cost. However, the potential of Li-S batteries has not yet been realized because of several technical barriers. Poor electrochemical performance is mainly attributed to the low electrical conductivity of the fully charged and discharged species, the irreversible loss of polysulfide anions and the decrease in the number of electrochemically active reaction sites during battery operation. Here, we report that the introduction of graphene quantum dots (GQDs) into the sulfur cathode dramatically enhanced sulfur/sulfide utilization, yielding high performance. In addition, the GQDs induced structural integrity of the sulfur-carbon electrode composite by oxygen-rich functional groups. This hierarchical architecture enabled fast charge transfer while minimizing the loss of lithium polysulfides, which is attributed to the physicochemical properties of GQDs. The mechanisms through which excellent cycling and rate performance are achieved were thoroughly studied by analyzing capacity versus voltage profiles. Furthermore, experimental observations and theoretical calculations further clarified the role played by GQDs by proving that C-S bonding occurs. Thus, the introduction of GQDs into Li-S batteries will provide an important breakthrough allowing their use as high-performance and low-cost batteries for next-generation energy storage systems. INTRODUCTIONRechargeable lithium-ion batteries are widely used in various applications, such as portable devices, bio-medical implants and electric vehicles, because of their high energy and power density. 1,2 However, current lithium-ion batteries based on the graphite and transition metal oxide couple have nearly reached their ceiling with respect to storage capability because of the limitations associated with their electrical properties and crystal structure. Therefore, breakthroughs in new energy storage systems that can surpass the current performance barrier of lithium-ion batteries should be brought about in a timely manner. Recently, Li-S batteries that can operate by the reversible electrochemical transformation between sulfur (S 8 ) and dilithium sulfide (Li 2 S) have attracted great attention because they can deliver high energy with a moderate voltage owing to the direct use of

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“…These results confirm the XRD ones and indicate that overall amounts of oxygen functionalities, their types, and distributions in the GO materials can be tailored by appropriate graphite oxidation parameters in agreement with earlier finding that harsher conditions and longer oxidation times result into an increased ratio of epoxides to hydroxyl groups (Boukhvalov and Katsnelson 2008;Jeong et al 2008). In the same time, the differences observed indicate a variation in the number of GO layers as shown to markedly affect the decomposition of oxygen groups, e.g., ketones and carboxyls remain above 400°C, and they are removed after a 650°C in three-layer GO materials (Acik et al 2011).…”

Section: Thermogravimetric Analysismentioning

confidence: 91%

Influence of synthesis conditions on properties of green-reduced graphene oxide

2013

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Green reduction of graphene oxide (GO) was performed using ascorbic acid (AA) in the presence of poly(sodium 4-styrenesulfonate), which resulted in reduced graphene oxide (PSS-rGO) with excellent solubility and stability in water. Large rGO sheets of 4 lm 2 area and 1.1-nm thickness were obtained. The measurements showed that noncovalent functionalization with PSS molecules prevented rGO from aggregation. The parameters of graphite oxidation process and AA:GO w/w ratio were evaluated, and the obtained results showed that the properties of the reduced material (PSS-rGO) can be tailored by proper selection and adjustment of these parameters.

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The Role of Oxygen during Thermal Reduction of Graphene Oxide Studied by Infrared Absorption Spectroscopy

Cited by 794 publications

References 129 publications

Probing the catalytic activity of porous graphene oxide and the origin of this behaviour

Probing the catalytic activity of porous graphene oxide and the origin of this behaviour

Graphene quantum dots: structural integrity and oxygen functional groups for high sulfur/sulfide utilization in lithium sulfur batteries

Influence of synthesis conditions on properties of green-reduced graphene oxide

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