<p>O, P co-doped porous carbon materials were successfully prepared by utilizing corn stalk as the carbon precursor, potassium citrate as the activating agent, and Na₂HPO₄ as both a co-activating agent and a dopant for O, P incorporation in this study, designated as CSPC-P-x. The resultant CSPC-P-x exhibited exceptional pore structures, featuring a high specific surface area, substantial pore volume, and a significant proportion of micropores. Notably, the introduction of Na₂HPO₄ significantly boosted the specific surface area of porous carbon materials. In a three-electrode system, the optimal CSPC-P-2 demonstrated superior capacitive performance of 334 F·g^‒1 in comparison with pristine CSPC of 171 F·g^‒1, as well as a stable capacitance retention of maintaining. Furthermore, the CSPC-P-2//CSPC-P-2 two-electrode symmetric supercapacitor delivered an impressive energy density of 7.4 Wh·kg⁻¹ at a high power density of 5000 W·kg⁻¹, which also exhibited remarkable cycle stability, with minimal degradation in capacitive performance after 10,000 cycles, underscoring its significant potential for practical applications.</p>