Immense Microporous Carbon@Hydroquinone Metamorphosed from Nonporous Carbon As a Supercapacitor with Remarkable Energy Density and Cyclic Stability

We report transformation of a cost-effective nonporous carbon (NC) to an immense microporous carbon (IMC) employing a simple chemical activation route at 750 °C. N₂ adsorption/desorption experiments revealed a remarkable increase in BET surface area (80-3030 m² g^-1) for successor nanomaterial (IMC) in comparison to precursor nanomaterial (NC) presumably due to enhanced accessibility of reaction surface area on carbon material for oxidants to react. In consequence, 250 times specific capacitance enhancement (2.5-605 F g^-1 at 0.5 A g^-1 current density) was observed in 2 M H₂SO₄ using a three-electrode configuration. Further, a massive specific capacitance of 1177 F g^-1 with a remarkable energy density of 163 Wh kg^-1 has been achieved by addition of hydroquinone in electrolyte with IMC (IMC@H₂Q) employing a two-electrode configuration. Notably, a simple electrode potential dependent chemical reversibility for hydroquinone redox chemistry in the long term cyclic experiment (95% capacitance retention after 5000 cycles) has been demonstrated wherein a strong electric field helped to avoid agglomeration of hydroquinone molecules inside the nanomaterial while hydrogen bond formation in IMC@H₂Q prevented chemical decomposition of benzoquinone and thus also provided efficient routes for electron/proton transport eluding annihilation of charge carriers.