Regulating directional transfer of electrons on polymeric g-C₃N₅ for highly efficient photocatalytic H₂O₂ production

Graphite carbon nitride (g-C₃N₅) has been widely used in various photocatalytic reactions due to its higher thermodynamic stability and better electronic properties compared to g-C₃N₄. However, it is still challenging to endow g-C₃N₅ with high performance on photocatalytic hydrogen peroxide (H₂O₂) production. Herein, potassium and iodine are co-doped into g-C₃N₅ (g-C₃N₅-K, I) for photocatalytic production of H₂O₂ with high efficiency. As expected, the photocatalytic H₂O₂ production rate over the g-C₃N₅-K, I (2933.4 μM h^-1) reaches to 84.22 times as that of g-C₃N₅. The excellent photocatalytic H₂O₂ production activity is mainly ascribed to the co-doping of K and I, which significantly improves the capacity of oxygen (O₂) adsorption, selectivity of two-electrons oxygen reduction reaction (2e^- ORR) and separation efficiency of charge carriers. The density functional theory (DFT) calculations reveal that O₂ molecules are more conducive to being adsorbed on g-C₃N₅-K, I. Besides, the result of excited states further indicates that photo-generated electrons can be directionally driven to the adsorbed O₂ molecules, which are effectively activated to form H₂O₂. The findings will contribute to new insights in designing and synthesizing g-C₃N₅ based photocatalysts for the H₂O₂ production.