Highly Accessible 3D Interconnected Macro/Microporous Catechol-Enriched Carbon Material to Clarify Its Excellent Pseudocapacitance

Unavoidable complicated oxygen functionalities in porous carbons restrict identification of their electrochemically active sites. Herein, we report 3D interconnected macroporous/microporous catechol-enriched carbon through first-step low-temperature pyrolysis and second-step melted KOH etching of resorcinol-formaldehyde resin and its excellent pseudocapacitance. First, high-content hydroxyl groups in a carbonaceous framework stem from preservation after low-temperature pyrolysis and introduction after KOH treatment. Second, molten KOH removes some carbon atoms in carbonaceous resin to form micropores and unstable domains to form macropores. Third, molten KOH promotes removal of some sp3-carbon atoms and/or their conversion to sp2-carbon atoms, forming a large-size conjugated plane to ensure electrical conductivity. Obvious reversible redox conversion between catechol and quinone groups during charge/discharge according to ex-situ O 1s XPS and GCD/CV analyses reliably confirms accessible catechol configurations in macro/microporous carbon as pseudocapacitive sites. Catechol-enriched carbon could be expanded to explore more electrochemical mechanisms.