An efficient pseudocapacitor electrode material with co-doping of iron (II) and sulfur in luminescent graphene quantum dots

Abstract

An efficient electrode material (Fe (II)S-GQDs) has been prepared by co-doping of sulfur and iron atoms with Graphene quantum dots. A top down synthesis method including a facile and one-pot hydrothermal was used to develop high capacity and good stability electrode material by selecting ferrous sulphate powder (FeSO4.7H2O) and graphene oxide (GO) as a precursor material. The results obtained from TEM measurements reveal the size alters from micrometer graphene sheets of GO to nano-meter dots for GQDs and Fe (II)S-GQDs. The electrochemical studies reveal that Fe(II) S doped GQDs can exhibit a reversible redox reaction with excellent specific capacitance of 476.2 F/g as compared to that of GQDs (143F/g). It has been found that there is an improvement in electrical conductivity and electron transfer in addition to the largest charge storage capacity. More remarkably, the doped electrode material shows a small charge transfer resistance (Rct) value (30 Ω) in case of Fe(II)S-GQDs as compared to GQDs (2.5 kΩ) due to fast diffusion of ion and electron between working electrodes and electrolyte.