K-modified cyano-rich carbon nitride for photocatalytic production of water treatment agent - Hydrogen peroxide in two-phase system

The transfer and separation of photogenerated carriers are an important factor limiting the yield of photocatalytic production of hydrogen peroxide (H 2 O 2 ) by graphite phase carbon nitride (g-C 3 N 4 ). In this paper, K and cyano groups(-C ≡ N) were added into the molecular structure of g-C 3 N 4 . The production capacity of the modified g-C 3 N 4 in the liquid-liquid two-phase reaction system composed of benzyl alcohol (BA) and water was 24 times that of the original g-C 3 N 4 . The improvement of photocatalytic performance can be attributed to the K-bridge formed by doped K in the molecular structure, which provides an additional channel for the transport of photogenerated carriers. As an electron absorbing group, -C ≡ N can trap photogenerated electrons to form vacancy defects , promoting carrier separation and charge migration. The application of two-phase system can effectively separate H 2 O 2 from oxidation products of sacrificial agents, promoting the forward progress of oxygen reduction synthesis of H 2 O 2 reaction. This study provides new insights for efficient production of H 2 O 2 by photocatalytic technology from the aspects of modification of photocatalysts and optimization of reaction conditions. • K modified cyano-rich carbon nitride was synthesized with salt assisted method. • The H 2 O 2 yield of the modified g-C 3 N 4 reached 24 times that of the original g-C 3 N 4 . • The synergistic effect of K doping and -C ≡ N defects enhance photocatalytic activity. • The forward progress of H 2 O 2 synthesis reaction is promoted in two-phase system.