Layer-by-layer assembly of iron oxide-decorated few-layer graphene/PANI:PSS composite films for high performance supercapacitors operating in neutral aqueous electrolytes

Abstract

The layer-by-layer assembly of polyaniline-PSS (PANI:PSS) complexes and iron oxide nanoparticles-decorated few-layer graphene (Fe-FLG) from aqueous dispersions, yielding an electrode material with excellent electrochemical capacitive performance in simple neutral aqueous electrolyte is presented. The simple dip-coating procedure allows the effective incorporation of both materials and the control of the film nanoarchitectonics. The resulting composite coating was characterized by XPS and Raman spectroscopies. A linear dependence of the capacitance on the film mass indicates that both building blocks are efficiently (and electrochemically) connected within the films. The electrochemical performance of the film-coated electrodes was tested in both acidic (0.1 M HCl) and neutral (0.1 M KCl) aqueous electrolytes. Electrodes constituted of 15 self-assembled bilayers showed the best performance with a high capacitance of 768.6 F g-1 and 659.2 F g-1 in 0.1 M HCl and 0.1 M KCl, respectively, at the current density of 1 A g-1. Moreover, a high stability to continuous cycling was observed, even in aqueous neutral solution (86% capacitance retention after 1600 cycles at 3 A g-1). This ternary material then constitutes a promising candidate for the construction of environmentally friendly supercapacitors.