Carbon Quantum Dot-Enabled Microcrystalline Domain Engineering for Selective Four-Electron Oxygen Reduction.

ABSTRACT Engineering carbon‐based electrocatalysts with well‐defined microcrystalline domains remain a central challenge for achieving efficient and durable oxygen reduction reaction (ORR) without relying on noble metals. Here, a carbon quantum dot (CQD)‐enabled microcrystalline domain engineering strategy that regulates graphitic ordering, electronic structure, and active‐site distribution in carbon catalysts is reported. The incorporation of CQDs during carbonization promotes the formation of spatially distributed microcrystalline domains, together with enriched B‐N coordination and optimized charge density. This structural configuration enhances O 2 activation and *O adsorption while suppressing peroxide pathways, thereby favoring a selective four‐electron ORR process. As a result, the optimized catalyst delivers a half‐wave potential approaching that of commercial Pt/C, together with a near four‐electron transfer pathway. When applied as the air cathode in zinc‐air batteries, it exhibits high power densities of 153 mW cm −2 in liquid cells and 123.8 mW cm −2 in flexible devices, along with stable operation over 1200 h. This work establishes CQD‐enabled microcrystalline domain engineering as an effective strategy for regulating structure‐property relationships in carbon electrocatalysts and provides design insights for high‐performance energy conversion devices.