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.
(© 2024. The Author(s).)