Molten salt synthesis of poly(benzoxazine)-based hierarchical porous carbons for dye adsorption and supercapacitor applications

Porous carbon materials are utilized in various applications related to environmental protection, as well as in energy storage and conversion. Nevertheless, traditional methods for preparing these porous carbon materials necessitate the use of a protective gas, such as nitrogen or argon, which complicates the process and leads to increased costs. In this study, we employed a straightforward and quick method to synthesize porous carbon materials in an air atmosphere, utilizing polybenzoxazine as the precursor and the molten salt method as the reaction medium. Thanks to the protective and etching properties of the molten salt, the resulting porous carbon achieved a maximum specific surface area of 1225 m² g⁻¹, which provided it with an impressive adsorption capacity of 354.61 mg g⁻¹ for methylene blue and a significant specific capacitance of 195 F g⁻¹. Furthermore, the zinc ion capacitor assembled with this porous carbon material exhibited a specific capacitance of 220 F g⁻¹. This research not only presents a type of high-performance porous carbon material but also emphasizes the important insights gained from the one-step carbonization approach for polybenzoxazine precursors without the need for protective gas.