Revealing the Nature of Cyano Groups Modified K, O Codoped Graphitic Carbon Nitride Toward Optimized Photocatalytic H₂ and H₂O₂ Evolution

The rapid charge separation and adequate surface-active sites are key points for photocatalytic H₂ and H₂O₂ evolution simultaneously. Here, cyano groups modified K, O codoped graphitic carbon nitride (KOCCN-X) is prepared through a thermal polymerization process utilizing KOH and urea as precursors. The resultant KOCCN-X exhibits obviously increased H₂ and H₂O₂ evolution, and the KOCCN-0.5 demonstrates the optimal photocatalytic performance, achieving H₂ and H₂O₂ production rates of 4.58 and 3.56 mmol g^-1 h^-1, which are ≈7.9 and 6.5 times higher than pristine g-C₃N₄ (CN), respectively. The structural analysis proves that K is doped at the layers of CN to form interlayer bridging via K-N coordination. O atom substitutes the N atom within the C─N═C bond in the formation of C─O─C linkage, and the cyano group is located at the edge of CN. Theoretical and experimental analysis ascertain that the interlayer bridging via K-N coordination acts as efficient electron migration channels, O and cyano groups can serve as active sites for H₂O₂ and H₂ production, respectively. The synergistic interplay between K, O, and cyano groups effectively boosts the photocatalytic H₂O₂ and H₂ performance. This study provides novel insights into the development of CN-based photocatalysts that can concurrently generate H₂ and H₂O₂.