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Carboxyl-Assisted Synthesis of Nitrogen-Doped Graphene Sheets for Supercapacitor Applications.

Xie B, Chen Y, Yu M, Shen X, Lei H, Xie T, Zhang Y, Wu Y - Nanoscale Res Lett (2015)

Bottom Line: The structure of the N-doped graphene with different surface functional groups was characterized by Raman spectroscopy.The research result indicates that the carboxylation of GO is the key factor to obtain pyridinic and pyridone N types during the N atom doping process.Compared to general N-doped graphene, the electrochemical test shows that specific capacitance of the GO-OOH-N sample reaches up to 217 F/g at a discharge current density 1 A/g and stable cycling performance (keep 88.8 % specific capacitance after 500 cycles at the same discharge current density) when applied to the supercapacitor electrode materials.

View Article: PubMed Central - PubMed

Affiliation: Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences, Wuhan 388 Lumo RD, Wuhan, 430074, China, 391856294@qq.com.

ABSTRACT
The high ratio of pyridinic and pyridone N-doped graphene sheets have been synthesized by functionalizing graphene oxide (GO) with different oxygen groups on its surface. The typical N-doped graphene was determined to be ~3-5 layers by transmission electron microscopy (TEM) and atomic force microscopy (AFM), and the nitrogen content was measured as 6.8-8 at. % by X-ray photoelectron spectroscopy (XPS). The structure of the N-doped graphene with different surface functional groups was characterized by Raman spectroscopy. The research result indicates that the carboxylation of GO is the key factor to obtain pyridinic and pyridone N types during the N atom doping process. Compared to general N-doped graphene, the electrochemical test shows that specific capacitance of the GO-OOH-N sample reaches up to 217 F/g at a discharge current density 1 A/g and stable cycling performance (keep 88.8 % specific capacitance after 500 cycles at the same discharge current density) when applied to the supercapacitor electrode materials.

No MeSH data available.


XPS C1s spectra of a GO and b GO-OOH
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Fig3: XPS C1s spectra of a GO and b GO-OOH

Mentions: As an effective tool to characterize elemental contents and bonding states in the samples, XPS technique can be used to understand the changes in oxygen and nitrogen content and their existing forms in the samples before and after reaction. Figure 3a shows that oxygen-containing groups of the GO sample were mainly composed of epoxy, hydroxyl, and carbonyl groups. After carboxylation of GO, the changes in the content of oxygen-containing groups caused the slight increase of total oxygen content (from 38.6 to 39.7 at. %). It can be seen in Table 1 that the contents of epoxy groups and hydroxyl groups decreased after carboxylation. On the contrary, the content of carboxyl groups increased considerably. Under strong alkaline condition, monochloroacetic acid can transform other oxygen-containing groups into carboxyl groups. Such transformation has been confirmed in previous reports [37, 38]. It should be noted that after the treatment, the intensity of the sp2 C-C peak was enhanced. The possible reason is that the carboxyl groups with high binding energy were introduced to the edge of graphene, while the epoxyl groups were distributed inside in-plane [31]. The reduction in the content of epoxyl groups was favorable for the recovery of graphitized C-C bond. The carboxylation of GO followed by reduction might be a potential method to obtain high-quality graphene.Fig. 3


Carboxyl-Assisted Synthesis of Nitrogen-Doped Graphene Sheets for Supercapacitor Applications.

Xie B, Chen Y, Yu M, Shen X, Lei H, Xie T, Zhang Y, Wu Y - Nanoscale Res Lett (2015)

XPS C1s spectra of a GO and b GO-OOH
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4542773&req=5

Fig3: XPS C1s spectra of a GO and b GO-OOH
Mentions: As an effective tool to characterize elemental contents and bonding states in the samples, XPS technique can be used to understand the changes in oxygen and nitrogen content and their existing forms in the samples before and after reaction. Figure 3a shows that oxygen-containing groups of the GO sample were mainly composed of epoxy, hydroxyl, and carbonyl groups. After carboxylation of GO, the changes in the content of oxygen-containing groups caused the slight increase of total oxygen content (from 38.6 to 39.7 at. %). It can be seen in Table 1 that the contents of epoxy groups and hydroxyl groups decreased after carboxylation. On the contrary, the content of carboxyl groups increased considerably. Under strong alkaline condition, monochloroacetic acid can transform other oxygen-containing groups into carboxyl groups. Such transformation has been confirmed in previous reports [37, 38]. It should be noted that after the treatment, the intensity of the sp2 C-C peak was enhanced. The possible reason is that the carboxyl groups with high binding energy were introduced to the edge of graphene, while the epoxyl groups were distributed inside in-plane [31]. The reduction in the content of epoxyl groups was favorable for the recovery of graphitized C-C bond. The carboxylation of GO followed by reduction might be a potential method to obtain high-quality graphene.Fig. 3

Bottom Line: The structure of the N-doped graphene with different surface functional groups was characterized by Raman spectroscopy.The research result indicates that the carboxylation of GO is the key factor to obtain pyridinic and pyridone N types during the N atom doping process.Compared to general N-doped graphene, the electrochemical test shows that specific capacitance of the GO-OOH-N sample reaches up to 217 F/g at a discharge current density 1 A/g and stable cycling performance (keep 88.8 % specific capacitance after 500 cycles at the same discharge current density) when applied to the supercapacitor electrode materials.

View Article: PubMed Central - PubMed

Affiliation: Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences, Wuhan 388 Lumo RD, Wuhan, 430074, China, 391856294@qq.com.

ABSTRACT
The high ratio of pyridinic and pyridone N-doped graphene sheets have been synthesized by functionalizing graphene oxide (GO) with different oxygen groups on its surface. The typical N-doped graphene was determined to be ~3-5 layers by transmission electron microscopy (TEM) and atomic force microscopy (AFM), and the nitrogen content was measured as 6.8-8 at. % by X-ray photoelectron spectroscopy (XPS). The structure of the N-doped graphene with different surface functional groups was characterized by Raman spectroscopy. The research result indicates that the carboxylation of GO is the key factor to obtain pyridinic and pyridone N types during the N atom doping process. Compared to general N-doped graphene, the electrochemical test shows that specific capacitance of the GO-OOH-N sample reaches up to 217 F/g at a discharge current density 1 A/g and stable cycling performance (keep 88.8 % specific capacitance after 500 cycles at the same discharge current density) when applied to the supercapacitor electrode materials.

No MeSH data available.