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.