Effects of Heteroatom Doping and Physicochemical Character on the Electrochemical Properties of Graphene Sheets

Abstract Graphene attracted great interest in the electrochemical applications due to its stability and extremely high surface area‐to‐mass ratio. Wet chemical and electrochemical synthesis allow affordable and single to multilayer graphenes with functional groups that contribute to surface accessibility, and electrolyte diffusion. These materials also have faradaic and pseudocapacitive reaction sites which enhance the electrochemical performance while altering their capacitive nature based on reaction type and density of these sites. Therefore, heteroatom doping of graphene has been studied widely, and various outcomes, some of which have been controversial, were reported. In this study, we investigated the doping modification with multiple samples and also conduct a detailed physicochemical characterization. Oxidation‐reduction and electrochemical exfoliation methods were utilized to synthesize pristine, nitrogen‐doped, and phosphorus‐doped reduced graphene oxide as well as the phosphorus‐doped and pristine electrochemically exfoliated graphene materials. Samples have been characterized in terms of doping level, particle size, number of layers, defect density, and exfoliation homogeneity. Electrochemical measurements showed that surface wrinkling property among similarly large rGO particles (~9x) and small lateral particle size (~2x) of graphenes are effective in determination of specific capacitance (C_specific) and capacitive characteristic of samples while heteroatom doping doesn't produce any significant change on these properties.