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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.


Schematic map of N doping types in GO and GO-OOH
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Fig5: Schematic map of N doping types in GO and GO-OOH

Mentions: In our experiments, hydrazine hydrate served as both reducing agent and nitrogen source for the treatment of GO, G-OH, and GO-OOH. When GO was used as the precursor material, increasing temperature is favorable for the generation of pyridinic nitrogen but hampers the generation of pyridone nitrogen and oxidized pyridinic nitrogen. This is because both oxidized pyridinic nitrogen and pyridone nitrogen contain oxygen groups. Increasing temperature would favor the reduction reaction which promoted the reduction of oxidized pyridinic and pyridone nitrogen into pyridinic nitrogen [17]. While GO-OOH was employed as the precursor material, the nitrogen content was increased under similar oxidization degree and identical nitrogen doping and reduction treatment conditions. With the reduction in epoxyl groups and the increase in carboxyl groups, the surface activity of graphene was enhanced [40]. Since these carboxyl groups introduced nitrogen into the active sites, the nitrogen content of graphene samples was increased. Moreover, more pyridinic nitrogen and pyridone nitrogen were produced, and the introduction of carboxyl groups had a greater impact on the generation of the former. The influence of experimental factors on nitrogen configuration can be depicted in Fig. 5. Although the high ratio of pyridinic and pyridone nitrogen was also obtained using G-OH as precursor, the total nitrogen content was low. Moreover, the G-OH-N had lower ratio of N/C/ % (4.8 %) than GO-OOH-N (10 %) which indicates that GO-OOH was more effective for N doping in graphene. Thus, the carboxylation of GO is the best choice to obtain high total nitrogen content and designed nitrogen types.Fig. 5


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)

Schematic map of N doping types in GO and GO-OOH
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig5: Schematic map of N doping types in GO and GO-OOH
Mentions: In our experiments, hydrazine hydrate served as both reducing agent and nitrogen source for the treatment of GO, G-OH, and GO-OOH. When GO was used as the precursor material, increasing temperature is favorable for the generation of pyridinic nitrogen but hampers the generation of pyridone nitrogen and oxidized pyridinic nitrogen. This is because both oxidized pyridinic nitrogen and pyridone nitrogen contain oxygen groups. Increasing temperature would favor the reduction reaction which promoted the reduction of oxidized pyridinic and pyridone nitrogen into pyridinic nitrogen [17]. While GO-OOH was employed as the precursor material, the nitrogen content was increased under similar oxidization degree and identical nitrogen doping and reduction treatment conditions. With the reduction in epoxyl groups and the increase in carboxyl groups, the surface activity of graphene was enhanced [40]. Since these carboxyl groups introduced nitrogen into the active sites, the nitrogen content of graphene samples was increased. Moreover, more pyridinic nitrogen and pyridone nitrogen were produced, and the introduction of carboxyl groups had a greater impact on the generation of the former. The influence of experimental factors on nitrogen configuration can be depicted in Fig. 5. Although the high ratio of pyridinic and pyridone nitrogen was also obtained using G-OH as precursor, the total nitrogen content was low. Moreover, the G-OH-N had lower ratio of N/C/ % (4.8 %) than GO-OOH-N (10 %) which indicates that GO-OOH was more effective for N doping in graphene. Thus, the carboxylation of GO is the best choice to obtain high total nitrogen content and designed nitrogen types.Fig. 5

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.