Nano-islands of CQDs anchored on carbon nitride for enhanced oxygen reduction through amidation polymerization with strong built-in electric field.

To address the persistent challenges in conventional photocatalytic systems for hydrogen peroxide (HO) production, such as sluggish charge separation kinetics, challenging selectivity control in the two-electron oxygen reduction (2e ORR) pathway, and inefficient mass transfer. It proposes an advanced interfacial engineering strategy that combines amide polymerisation-driven nanostructure engineering and electronic structure modulation. This enables the covalent anchoring of carbon quantum dot (CQDs) nano-islands onto a carbon nitride substrate. Within this architecture, the inherent polarity and resonance effects of amide bonds induce a strong built-in electric field (BIEF). This not only significantly optimizes the charge transport pathways at the interface but also enhances oxygen activation capacity by leveraging the unique "electron reservoir" properties of CQDs, thereby synergistically optimizing the kinetics of the ORR. BIEF effectively drives the separation of photo-generated electron-hole (e-h) pairs, thereby suppressing their recombination and ensuring that a large number of e can be directed toward the efficient synthesis of HO. This catalyst ultimately achieves an HO yield of 1509.49 μmol·g·h with outstanding cycling stability. This study provides a novel structural paradigm and mechanistic insights for developing highly efficient, selective HO photosynthetic systems, demonstrating broad application prospects in clean energy conversion and environmental pollution control.