Circumventing bottlenecks in H 2 O 2 photosynthesis over carbon nitride with iodine redox chemistry and electric field effects.

Artificial photosynthesis using carbon nitride (g-C 3 N 4 ) holds a great promise for sustainable and cost-effective H 2 O 2 production, but the high carrier recombination rate impedes its efficiency. To tackle this challenge, we propose an innovative method involving multispecies iodine mediators (I - /I 3 - ) intercalation through a pre-photo-oxidation process using potassium iodide (suspected deteriorated "KI") within the g-C 3 N 4 framework. Moreover, we introduce an external electric field by incorporating cationic methyl viologen ions to establish an auxiliary electron transfer channel. Such a unique design drastically improves the separation of photo-generated carriers, achieving an impressive H 2 O 2 production rate of 46.40 mmol g -1 h -1 under visible light irradiation, surpassing the most visible-light H 2 O 2 -producing systems. Combining various advanced characterization techniques elucidates the inner photocatalytic mechanism, and the application potential of this photocatalytic system is validated with various simulation scenarios. This work presents a significative strategy for preparing and applying highly efficient g-C 3 N 4 -based catalysts in photochemical H 2 O 2 production.