Flash Joule heating-engineered multi-walled carbon nanotubes for metalfree H2O2 electrosynthesis

<jats:p> Metal-free carbon materials are important electrocatalysts for two-electron oxygen reduction toward H <jats:sub>2</jats:sub> O <jats:sub>2</jats:sub> production owing to their low cost, good conductivity and tunable surface chemistry. Herein, we report flash Joule heating (FJH)-engineered multi-walled carbon nanotubes (MWCNTs) for selective H <jats:sub>2</jats:sub> O <jats:sub>2</jats:sub> electrosynthesis. FJH induces partial wall exfoliation and structural reconstruction of MWCNTs, enabling the simultaneous regulation of oxygen-containing defects, edge site exposure and graphitic conductivity. The sample treated at 1200 °C (denoted as MWCNTs-1200) preserves abundant oxygen-containing defects while exposing additional edge sites through partial wall exfoliation, providing a balanced structure for efficient 2e <jats:sup>-</jats:sup> ORR. MWCNTs-1200 delivers an H <jats:sub>2</jats:sub> O <jats:sub>2</jats:sub> production rate of 10.57 mol g <jats:sub>cat</jats:sub> <jats:sup>-1</jats:sup> h <jats:sup>-1</jats:sup> at 200 mA cm <jats:sup>-2</jats:sup> with a Faradaic efficiency of 85%, and maintains stable operation for 10 h at 100 mA cm <jats:sup>-2</jats:sup> , with the Faradaic efficiency decreasing only moderately from 94.6% to 82.2%. This work highlights FJH as an effective strategy to regulate CNT structure for efficient H <jats:sub>2</jats:sub> O <jats:sub>2</jats:sub> electrosynthesis. </jats:p>