Pyrolysis-Free Mechanochemical Conversion of Small Organic Molecules into Metal-Free Heteroatom-Doped Mesoporous Carbons for Efficient Electrosynthesis of Hydrogen Peroxide

The synthesis of heteroatom-doped porous carbons for efficient electrochemical production of hydrogen peroxide (H2O2) through two-electron (2e–) oxygen reduction reaction (ORR) has attracted increasing research attention since it offers a promising renewable substitute for the traditional complex energy-intensive anthraquinone process. Herein, a novel pyrolysis-free mechanochemical approach was developed for straightforward conversion of small organic molecules into metal-free heteroatom-doped mesoporous carbons (HMCs), where the uniqueness of this one-pot ball-milling technique not only exceeds the limit of volatilities of traditional carbonaceous precursors but also eliminates the need for any additional mesoporous templates. The abundance of molecular precursors (up to 23 different molecules) provides a facile means to introduce a wide variety of heteroatoms (B, N, O, P, S, F, Cl, etc.) into the resultant carbon materials, accompanied by in situ formation of rich mesopores. As a result, the resulting N/O co-doped mesoporous carbon with the highest Brunauer–Emmett–Teller (BET) surface area of 1238 m2 g–1 exhibits exceptional H2O2 selectivity of 95.2% in 0.1 M KOH solution at 0.70 V (vs. reversible hydrogen electrode, RHE) and a large H2O2 production rate of ca. 265 mmol gcat.–1 h–1, ranking at the top among all metal-free carbonaceous electrocatalysts. We anticipate our findings will facilitate new possibilities for the development of mesoporous carbons for electrocatalytic applications.