Photochemical Synthesis of Porous Triazine‐/Heptazine‐Based Carbon Nitride Homojunction for Efficient Overall Water Splitting

Abstract Porous triazine‐/heptazine‐based carbon nitride (THCN) homojunction with chloride (Cl) doping was synthesized by a simple, one‐step photochemical synthesis route for efficient visible‐light‐driven overall water splitting. The phase ratio of triazine‐based carbon nitride (TCN) and heptazine‐based carbon nitride (HCN), texture and morphology of the THCN isotype junction were finely tuned by varying ultraviolet irradiation time and washing solvents. After washing with acetonitrile, the resulting porous THCN nanosheets with 48 h irradiation contain 21 wt % TCN and 79 wt % HCN units and reveal a significantly improved photocatalytic performance with H 2 and O 2 production rates up to 7.9 and 4.2 μmol h −1 , respectively, about 3.8 times higher than that of THCN prepared by 36 h illumination. The dual‐phase interaction, holey structure, and Cl dopants favor the exposure of active sites, extended visible‐light harvesting, accelerated charge transfer, and enhanced photoreduction ability, thereby improving photocatalytic activity.