Triazine-based COP/Mn₂O₃ composite for supercapacitors: unraveling the electrolyte-dependent charge storage mechanism

A covalent organic polymer (COP) composite incorporated with Mn₂O₃ (COP/Mn₂O₃) was synthesized and systematically explored for supercapacitor applications. FTIR confirmed successful polymerization and Mn incorporation, whereas XRD revealed π–π stacking and bixbyite Mn₂O₃ phases. FE-SEM revealed morphological densification, and EDS/XPS analyses confirmed that uniform Mn dispersion and mixed Mn^{2 +} /Mn³⁺ states enhanced redox activity. BET analysis revealed a mesoporous structure with an average pore diameter of 14.81 nm. A key novelty of this study lies in the multielectrolyte electrochemical evaluation conducted in aqueous (1 M H₂SO₄ and 1 M Na₂SO₄) and organic (1 M NaPF₆ in propylene carbonate) media, providing deeper insight into electrolyte-dependent charge storage mechanisms. In 1 M H₂SO₄, the COP/Mn₂O₃ composite achieved a high specific capacitance of 660 F g⁻¹ at 5 mV s⁻¹ and 232.8 F g⁻¹ at 1 A g^−1, with an excellent energy density of 21 Wh kg⁻¹ and a superior power density of 10,000 W kg⁻¹. The fabricated symmetric supercapacitor device delivered an energy density of 5.8 Wh kg⁻¹, a power density of 2500 W kg⁻¹, and excellent cycling stability with 93.3 % capacitance retention after 10,000 cycles in a 1 M H₂SO₄ electrolyte. These results highlight COP/Mn₂O₃ as a promising electrode material for next-generation supercapacitors.