Interaction between Nitrogen and Sulfur in Co-Doped Graphene and Synergetic Effect in Supercapacitor

Abstract

The co-doping of graphene with nitrogen and sulfur was investigated aiming at understanding their interactions with the presence of oxygen in graphene. The co-doped graphene (NS-G) was synthesized via a one-pot hydrothermal route using graphene oxide as starting material and L-cysteine, an amino acid containing both N and S, as the doping agent. The obtained NS-G with a three-dimensional hierarchical structure containing both macropores and mesopores exhibited excellent mechanical stabilities under both wet and dry conditions. As compared to N or S singly doped graphene, the co-doped sample contains significantly higher concentrations of N and S species especially pyrollic N groups. The co-doped sample considerably outperformed the singly doped samples when used as free-standing electrode in supercapacitors due to enhanced pseudocapacitance. The simultaneous incorporation of S and N species with the presence of oxygen significantly modified the surface chemistry of carbon leading to considerably higher doping levels, although directly bonding between N and S is neither likely nor detected. Hence, the synergetic effect between N and S occurred through carbon atoms in neighboring hexagonal rings in a graphene sheet.

Probing the electrochemical properties of an electrophoretically deposited Co3O4/rGO/CNTs nanocomposite for supercapacitor applications

“…Presently, due to absolute mesoporous structure, remarkable accessible surface area, high conductivity and excellent chemical stability the carbon materials like CNTs and graphene are among the most attractive materials for supercapacitors research. 18 It has been reported that nitrogen35 doping in graphene significantly enhance its pore volume, electrical conductivity, surface area and mechanical strength and hence improve its electrochemical performance 19,20. In this study, we have synthesized hybrid nanocompositesof Co 3 O 4 with reduced graphene oxide (rGO) and MWCNTs via 40 hydrothermal route and a simple electrophoretic deposition (EPD) technique has been utilized to make binder free Co 3 O 4 /rGO/CNT nanocomposite electrodes.…”

Facile synthesis of T-Nb2O5 nanosheets/nitrogen and sulfur co-doped graphene for high performance lithium-ion hybrid supercapacitors

“…4d shows the S 2p spectrum of the T-Nb 2 O 5 /NS-G hybrid. The peaks at 164.2 and 165.7 eV are assigned to the C-S-C covalent bond of thiophene-S, and the peak at 169.9 eV can be attributed to the oxidized-S groups (C-SO x -C) [40]. The appearance of thiophene-S may contribute to the enhancement of conductivity of doped graphene.…”

Biomass‐Derived Electrode for Next Generation Lithium‐Ion Capacitors

“…Also, this high energy density offset the other carbonbased Li-HEC reportede lsewhere [e.g.,a ctivated microwave expanded graphite oxide (a-MEGO)//graphite in Li-electrolyte (147.8 Wh kg À1 ), [14] pre-lithiated graphene//AC (61.7 Wh kg À1 ), [42] pre-lithiated graphite//urea reducedg raphitic oxide (URGO, 106 Wh kg À1 ), [43] Li decorated niobium nitride/nitrogen-doped graphene hybrid material (NbN/NG)//AC (122.7 Wh kg À1 ), [44] and hard carbon withs tabilized Li metal powder//AC (82 Wh kg À1 )]. [45] We strongly believe the superiore lectrochemical performance of Li-HEC are mainly ascribed to the (i)tubelike cracked structuredA C, which allows easier transportation of the chargec arriers and can easily access the complete active material, (ii)the large specific surface area with tailored porosityc ertainly accommodates more Li + andP F 6 À ,w hich can easily adsorbed/desorbed on surface of PJ-AC, (iii)a relative percentage of Na nd Sa nd its synergistic effect in PJ-AC providing more Li-ion binding sites, [46] which obviously enhances the specific energy and powder capability of Li-HEC, (iv) presenceo flayered type of thin graphitic layers on PJ-AC facilitates fast electron transport to realize the high performance Li-HEC, and (v) the source material for the AC cannotb er uled out. Further studies are in progress on the counter electrode, especially the insertion-type material (e.g.,h ard carbon), to widen the energy density of the Li-HEC.…”