Tailored ionic liquid for metal-free carbons toward oxygen reduction reaction

•The π-e enriched ionic liquid for metal-free ORR catalyst preparing is proposed.•A way to prepare the π-e enriched ionic liquid is described.•A way to select ionic liquid precursor for metal-free ORR catalyst is proposed. Carbon catalysts have been widely used for various electrochemical reactions including oxygen reduction reaction (ORR) and their catalytic activities are significantly dependent on carbon precursors. Ionic liquids (ILs) are promising precursors of heteroatom-doped carbon electrocatalysts for ORR. Herein, we demonstrated that an IL tailored with π-π conjugated interaction introduced by a π-electron enriched aromatic ring can offer a carbon material with improved ORR activity. π-electron tailored ionic liquid as precursor for metal-free catalyst toward oxygen reduction reaction. [Display omitted]