Structured Conducting Polymers Templated from Ouzo-Induced Oxidant Superstructures for High-Performance Supercapacitors

Conducting polymers (CPs) that are structured in very specific shapes have been successfully synthesized via vapor phase chemical oxidative polymerization of monomers with oxidant superstructures as templates. A ternary mixture of iron(III) p-toluenesulfonate hexahydrate (Fe(pts)3·6H2O) as the oxidant, n-butanol as the solvent, and cyclohexane as the anti-solvent has been found to form an unstable Ouzo emulsion, leading to the precipitation of the oxidant within emulsion drops into nano-sized particles. Interestingly, the formed oxidant nanoparticles then aggregated spontaneously into specific shapes, forming superstructures. The oxidant superstructures took the shape of micron-scale rods initially, which underwent shape transformation into a few micron-sized plates, and then finally into tens of microns-long nanofibers. These oxidant superstructures (rods, plates, or fibers) have been found to retain their oxidizing properties for the polymerization of various CPs, enabling us to prepare structured CPs in rod, plate, and fiber shapes. Especially, the fiber-shaped oxidant superstructures were used for the synthesis of nanofibrous PEDOT films for supercapacitors. The PEDOT nanofiber film exhibited a specific capacitance of 114.3 F/g, significantly higher than that of the dense PEDOT film (54.2 F/g), with capacitance retention of 73% under rate testing thanks to its electrochemical stability. Furthermore, the PEDOT nanofiber film exhibited lower charge transfer resistance (Rct) and equivalent series resistance (ESR) compared to the dense film, demonstrating superior charge transfer characteristics at the interface.