Si/Carbon‐dots with Surface N‐C Sites Promoting Proton and Electron Transfers in Oxygen Reduction Reaction
Yankun Wang, Mingxian Zhang, Haihua Wu, Meirong Huang, Yuanxing Fang, Masakazu Anpo, Xinchen Wang
Abstract
Abstract The oxygen reduction reaction (ORR) can proceed through either a two‐ or four‐electron pathway, both of which are important for a wide range of applications. The intermediate conversion of *O 2 ⁻ + H⁺ → *OOH recognized as the rate‐determining step in ORR, with its efficiency strongly dependent on the nature of active sites at the surface of a catalyst. Herein, Si‐supported carbon dots (Si‐CDs) are introduced as cocatalysts in a photocatalytic system, where their nitrogen–carbon sites play a pivotal role in lowering the energy barrier for *OOH formation by promoting proton and electron transfers, thus enhancing the H 2 O 2 production rate in ORR. This strategy is broadly applicable across a wide range of photocatalysts, both with and without use of sacrificial agents. The H 2 O 2 production rate for Zn 0.5 Cd 0.5 S (30 mg) increased from 13.0 to 40.9 µmol h −1 when 0.6 mg of Si‐CDs were added. In‐situ characterizations and theoretical simulations are conducted to reveal the reaction pathway and the reduced energy requirements for the *O 2 ⁻ + H⁺ → *OOH conversion. This study provides a unique example of overcoming a key barrier in ORR using a metal‐free catalyst and promotes potential applications in various fields.