Mechanistic investigation of the graphene functionalization using p-phenylenediamine and its application for supercapacitors

o‐Benzenediol‐Functionalized Carbon Nanosheets as Low Self‐Discharge Aqueous Supercapacitors

“…Figure 3a presents the CV curveso ft he NDC//NDC and NDC-400 th //NDC-400 th supercapacitors at as can rate of 25 mV s À1 .C learly,t he NDC-400 th //NDC-400 th cell showed increased capacitance, compared with the NDC//NDC and NDC-DA//NDC-DA (NDC-DA denotes that NDC was directly tested in 0.5 m H 2 SO 4 containing 0.05 m 3,4-dihydroxyhydrocinnamic acid) counterparts. At ac urrent density of 0.5 Ag À1 ,t he calcu-lated capacitance was 565 Fg À1 ,w hichw as higher than that of the reported PANI/GO//PANI/GO( 422 Fg À1 ;P ANI = polyaniline, GO = graphene oxide), [21] rGO-a-PoPD//rGO-a-PoPD (381 Fg À1 ; rGO = reduced graphene oxide,a -PoPD = aniline-anchored poly(o-phenylenediamine)), [38] PPD-modifiedG O//PPD-modified GO (303 Fg À1 ;P PD = p-phenylenediamine) [23] supercapacitors The GCD profiles of positiveand negativee lectrodes of a) NDC andb)NDC-400 th ,a nd the calculated plane-averaged electrostatic potential profiles for grafted NDC through c) pyridinic Na nd d) pyrrolic N. The current density usedi nthe charge/discharge experiment is 10 Ag À1 . To further investigate the electrochemical ChemSusChem 2018, 11,3307 -3314 www.chemsuschem.org performance of the NDC-400 th electrode, the GCD performance was also evaluated, with current densities ranging from 0.5 to 200 Ag À1 (Figure3c).…”

“…Very broad peaks in the curves were consistent with the redox peaks in the CV results, which suggested the presence of pseudocapacitive behavior during the charge/ discharge process. At ac urrent density of 0.5 Ag À1 ,t he calcu-lated capacitance was 565 Fg À1 ,w hichw as higher than that of the reported PANI/GO//PANI/GO( 422 Fg À1 ;P ANI = polyaniline, GO = graphene oxide), [21] rGO-a-PoPD//rGO-a-PoPD (381 Fg À1 ; rGO = reduced graphene oxide,a -PoPD = aniline-anchored poly(o-phenylenediamine)), [38] PPD-modifiedG O//PPD-modified GO (303 Fg À1 ;P PD = p-phenylenediamine) [23] supercapacitors Figure 2. The GCD profiles of positiveand negativee lectrodes of a) NDC andb)NDC-400 th ,a nd the calculated plane-averaged electrostatic potential profiles for grafted NDC through c) pyridinic Na nd d) pyrrolic N. The current density usedi nthe charge/discharge experiment is 10 Ag À1 .…”

“…[21][22][23][24] By cycling the electrode in the electrolyte containing the target species, the charge density of the electrode can be influenced, due to chemical grafting. However,t he Widening the voltage window is often proposed as aw ay to increaset he energy density of aqueous supercapacitors.…”

“…[a] T. Xiong role of redox molecules in self-discharge has been less investigated. [21][22][23][24] By cycling the electrode in the electrolyte containing the target species, the charge density of the electrode can be influenced, due to chemical grafting. Hence, in this way, the PZC of the individual electrode can be shifted to as uitable potential, leading to effective usage of the voltage window by each of the electrodes.…”

Graphene‐Based Planar Microsupercapacitors: Recent Advances and Future Challenges

“…The presence of abundant hydrophilic groups on the surface of graphene oxide (GO), the oxidized form of graphene, enables efficient dispersion in aqueous and some of the organic solvents for thin‐film synthesis via different techniques . Although the electrical resistance of GO is higher, reduced GO (RGO) can be converted via various techniques, e.g., thermal, optical, chemical, or electrochemical process, etc., to reinstate the high electrical conductivity . By introducing various electroactive materials including carbon nanotubes (CNTs), metal oxides/hydroxides, and conductive polymers, the electrochemical performance of graphene can be further improved …”