Orchestrating surface oxygen functionalities and pore structure of porous carbon for supercapacitors via a tandem coupling strategy of low-dose (NH4)2SO4 and KOH

Using oxygen-rich medium- and low- temperature coal tar pitch enables intrinsic O-doping. • Low-dose (NH 4 ) 2 SO 4 achieves pre-oxidation of the raw materials. • Low-dose KOH activation produces uniform mesopores with 54% carbon yield. • A sequential low-dose strategy achieves synergistic pore-surface control. • MPC-700 achieves a specific capacitance of 367 F g −1 (at 5 A g −1 ). High-performance supercapacitors require electrode materials with suitable pore structures and abundant surface functional groups. Herein, a tandem oxidation-activation strategy is proposed to prepare coal-tar pitch-derived hierarchical porous carbon (MPC-700) rich in quinonyl groups. Low-dose (NH 4 ) 2 SO 4 pre-treatment significantly increases the oxygen content of the precursor, enhances the quinonyl group content in the porous carbon, and improves the pore structure, leading to a higher specific surface area. DFT calculations reveal that quinone-induced carbon vacancies reduce K⁺ adsorption energy, enhancing ion storage kinetics. Benefiting from the synergistic effect of hierarchical pores and quinone groups, MPC-700 achieves a specific capacitance of 367.0 F g −1 in 6 M KOH with excellent cycling stability. This work demonstrates a tandem coupling effect between low-dose modifiers and activators on oxygen-rich coal tar pitch, where pre-oxidation and pre-etching dictate the final pore structure and surface chemistry. This strategy offers a low-cost, green route for preparing porous carbon for energy storage applications. The porous carbon material, characterized by rich defect sites, a abundant quinonyl active functional groups, and a uniform porous structure, delivers outstanding electrochemical performance when employed as a supercapacitor electrode. Download: Download high-res image (437KB) Download: Download full-size image