Fast and reversible redox reaction of polyNi(salphen)@reduced graphene oxide/multiwall carbon nanotubes composite for supercapacitors

Abstract

π-conjugated Schiff base metal complex polymer was easily synthesized onto reduced graphene oxide (rGO), multiwall carbon nanotubes (MWCNTs), polished titanium substrate and rGO/MWCNTs support electrodes from [N, N′-bis(salicylidene)-o-phenylenediamine] nickel(II) complex, Ni(salphen), by the route of Cyclic Voltammogram (CV) method, respectively. The morphologies of the polyNi(salphen) on different support electrodes was evaluated by field emission scanning electron microscopy (FESEM). X-ray photoelectron spectroscopy (XPS) measurement was carried out to shed light on the polymerization mode and energy storage mechanism. Meanwhile, the potential-step chronoamperometry was carried out to assess the charge transport dynamics. The result signals that the azomethine nitrogen group (NCH) in polyNi(salphen) with arrangement of the π-conjugated system upon the electron transfer path at intramolecular of the macrocycle instead of the Ni2+/Ni3+ process generate the energy storage capacity by reversible charge transfer. Due to the combining effect of the electrochemical double layer capacitor (EDLC) and pseudocapacitive of the polyNi(salphen) caused by faradaic capacitance, the specific capacitances of the composite electrodes exhibit 60% higher than that of the rGO/MWCNTs support electrodes. Furthermore, the strong π–π interactions between rGO/MWCNTs support electrode and the π-conjugated systems in polyNi(salphen) leads to better energy storage and kinetic behavior.