Abstract
Graphene oxide (GO)-modified polypyrrole (PPy) coatings were obtained by electrochemical methods in the presence of the anionic surfactant, sodium dodecyl sulfate (SDS). The structure, morphology, and electrochemical properties of the coatings were assessed by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM) and cyclic voltammetry at varying scan rates, respectively. The properties of the obtained coatings were analyzed with the GO and PPy loadings and electrodeposition mode. The hybrid coatings obtained galvanostatically showed a coarser appearance than those deposited by cyclic voltammetry CV mode and improved performance, respectively, which was further enhanced by GO and PPy loading. The capacitance enhancement can be attributed to the SDS surfactant that well dispersed the GO sheets, thus allowing the use of lower GO content for improved contribution, while the choice of suitable electrodeposition parameters is highly important for improving the applicability of GO-modified PPy coatings in energy storage applications.
Highlights
The long cycle life, high power and energy density, and short-time charge/discharge of the electrochemical capacitors allow them to fill the technology gap between batteries and traditional capacitors [1,2,3,4,5,6]
graphene oxide (GO) could serve as a supporting electrolyte for the deposition of PPy [24], and its oxygen groups would strongly interact with nitrogen atoms in the NH group of the PPy back-bone [25], the NapTS was employed to improve the conductivity of the solution
The electropolymerization onset in the case of the pure PPy appeared at about 0.6 V, while in the presence of GO, it shifted toward 0.8 V
Summary
The long cycle life, high power and energy density, and short-time charge/discharge of the electrochemical capacitors allow them to fill the technology gap between batteries and traditional capacitors [1,2,3,4,5,6]. Two mechanisms are involved in the energy storage: (i) electrical double layer capacitance due to adsorption/desorption processes at the electrode/electrolyte interface for which carbon based materials including carbon nanotubes, graphene, and activated carbon are considered due to their high specific surface area and long cycle life; and (ii) pseudocapacitance, which involves rapid and reversible surface Faraday reactions and usually employs a transition metal oxide/hydroxide or conducting polymers due to their high specific capacitance and energy density [2,4,6,8,10]. A derivative of graphene, graphene oxide (GO), can be employed as it possesses oxygen groups obtained by varying methods including wet chemistry, which confer it with high dispersibility in varying solvents [17]
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