Rapid and green microwave-assisted synthesis of hydroxyl-rich mesoporous carbon for high-performance supercapacitors

Mesoporous and hydroxyl group-abundant carbon (MPHAC) was synthesized via a rapid, energy-efficient microwave-assisted process utilizing phytic acid as a precursor. The synthesis process comprised two short sub-microwave irradiation steps: (1) the formation of phosphorus (P)-doped and oxygen (O)-abundant graphitic carbon (POGC) for 3 min and (2) surface treatment of POGCs using rapid thermal treatment with an aqueous potassium hydroxide solution for 5 min. The microwave-assisted post-treatment process generated 2–3 nm dominant mesopores and abundant hydroxyl groups without destruction of main pore structure of POGC, resulting in a higher surface area (1667.97 m² g⁻¹), enhanced hydrophilicity, and stronger interaction with potassium ions. Benefitting from the unique microstructure, the supercapacitor using MHAPC exhibited 31.2 Wh kg⁻¹ of energy density of 250 W kg⁻¹ of power density, and maintained superior performance under extreme high power density conditions (20.8 Wh kg⁻¹ at 25 kW kg⁻¹). The capacitance retention of 98.9 % after 10,000 cycles highlights its outstanding stability. The combined benefits of MPHAC showcases the potential of MPHAC as a high-performance, eco-friendly electrode material for next-generation energy storage devices, providing a scalable and sustainable pathway for supercapacitor development.