Physical properties of heteroatom doped graphene monolayers in relation to supercapacitive performance
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Tarih
2020
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Natl Inst Science Communication-Niscair
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
Electrodes fabricated using graphene are quite promising for electric double layer capacitors. However graphene has the limitations of low 'Quantum Capacitance (QC)' near fermi level due to the presence of Dirac point that can be modified by doping graphene with suitable dopant. The density functional theory DFT calculations are performed for doped graphene using Boron, Sulphur and phosphorus as dopants to improve the quantum capacitance of electrodes fabricated using graphene. The calculations are performed at temperatures of 233, 300 and 353 degrees K. From present calculations no significant temperature dependence of quantum capacitance is observed, however a marked increase in QC of value above 58Fcm(-2) is seen. Forphosphorus and Sulphur doped graphene a significant energy gap shift of similar to 1.5 eV from the Fermi level is observed that significantly increases the QC at Fermi level to a high value of similar to 35 mu Fcm(-2). With boron dopant as well, a shift of energy gap similar to 1.25eV from the Fermi level is observed. The shift in Dirac point increases quantum capacitance at Fermi level that in turn can increase the energy density of supercapacitor remarkably. The effect of increasing doping concentration on quantum capacitance is also investigated. These results suggest that doping of graphene may result in significant increase in QC near Fermi level, if the dopants are selected carefully depending upon the use of graphene as a positive or negative electrode. The results of these calculations reveal that the problem of low QC of graphene in the range of interest can be addressed by modifying itssurface and structure chemistry which may increase energy density in supercapacitors.
Açıklama
Anahtar Kelimeler
Quantum capacitance, Graphene, Density of States, Band Structure, Supercapacitor
Kaynak
Indian Journal Of Pure & Applied Physics
WoS Q Değeri
Q4
Scopus Q Değeri
Cilt
58
Sayı
12
