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 (<b>NC</b>) to an immense microporous carbon (<b>IMC</b>) 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 (<b>IMC</b>) in comparison to precursor nanomaterial (<b>NC</b>) 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 <b>IMC</b> (<b>IMC@H</b>_<b>2</b><b>Q)</b> 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 <b>IMC@H</b>_<b>2</b><b>Q</b> prevented chemical decomposition of benzoquinone and thus also provided efficient routes for electron/proton transport eluding annihilation of charge carriers.