Scalable One-Step Synthesis of Graphene/Polyaniline Films via Dual-Functional H₂SO₄ for Supercapacitor Electrodes

Supercapacitors serve as an important complement to batteries in sustainable energy storage and utilization systems, necessitating the efficient preparation of high-performance electrodes for practical applications. Here, we present a scalable one-step strategy for fabricating integrated graphene/polyaniline electrodes directly on current collectors, enabled by the dual functionality of H2SO4 in a rapid 20 min process. Initially, dilute H2SO4 acts as a protonation medium to facilitate the oxidative polymerization of aniline by ammonium persulfate. Subsequently, thermally induced water evaporation concentrates H2SO4 into an effective reducing agent for graphene oxide reduction. This method eliminates the need for additional reducing agents while producing binder-free integrated electrodes without postprocessing. Moreover, by repeating this approach, a large mass loading of the graphene/polyaniline composite can be realized. The optimized electrode achieves an impressive specific capacitance of 729 F g-1 at a current density of 1 A g-1 with a high retention of 74% at 20 A g-1, and the corresponding symmetric supercapacitor delivers an energy density of 22.8 Wh kg-1. This work provides a scalable, green, and low-energy method for the preparation of graphene-based supercapacitor electrodes.