Isomerization Engineering of Oxygen‐Enriched Carbon Quantum Dots for Efficient Electrochemical Hydrogen Peroxide Production

Abstract Hydrogen peroxide (H 2 O 2 ) has emerged as a kind of multi‐functional green oxidants with extensive industrial utility. Oxidized carbon materials exhibit promises as electrocatalysts in the two‐electron (2e − ) oxygen reduction reaction (ORR) for H 2 O 2 production. However, the precise identification and fabrication of active sites that selectively yield H 2 O 2 present a serious challenge. Herein, a structural engineering strategy is employed to synthesize oxygen‐doped carbon quantum dots (o‐CQD) for the 2e − ORR. The surface electronic structure of the o‐CQDs is systematically modulated by varying isomerization precursors, thereby demonstrating excellent electrocatalyst performance. Notably, o‐CQD‐3 emerges as the most promising candidate, showcasing a remarkable H 2 O 2 selectivity of 96.2% (n = 2.07) at 0.68 V versus RHE, coupled with a low Tafel diagram of 66.95 mV dec −1 . In the flow cell configuration, o‐CQD‐3 achieves a H 2 O 2 productivity of 338.7 mmol g catalyst −1 h −1 , maintaining consistent production stability over an impressive 120‐hour duration. Utilizing in situ technology and density functional theory calculations, it is unveil that edge sites of o‐CQD‐3 are facilely functionalized by C‐O‐C groups under alkaline ORR conditions. This isomerization engineering approach advances the forefront of sustainable catalysis and provides a profound insight into the carbon‐based catalyst design for environmental‐friendly chemical synthesis processes.