Benzene Ring Engineering of Graphitic Carbon Nitride for Enhanced Photocatalytic Dye Degradation and Hydrogen Production from Water Splitting

The photocatalytic activity of graphitic carbon nitride (g‐C 3 N 4 ) strongly depends on its electronic structure. To design the photocatalysts with efficient charge separation and transfer property, here a benzene ring‐doped g‐C 3 N 4 via one‐pot thermal polycondensation of dicyandiamide and 2,4‐diaminobenzenesulfonic acid is reported. The carbon‐rich benzene ring is embedded into g‐C 3 N 4 , which enables the asymmetric modification of the heptazine units in g‐C 3 N 4 and the extension of the π‐conjugate system without altering its long‐range order structure significantly. Such molecular structure optimization effectively improves the visible light harvesting and charge carriers separation ability. A high photocatalytic hydrogen evolution rate and dye degradation performance is achieved under visible light irradiation (λ > 420 nm), which is about 8.4 and 4.4‐fold higher than that of pristine g‐C 3 N 4 , respectively. The reason for enhanced photocatalytic performance is ascribed to a favorable optical property, suppressed charge carrier recombination, and efficient charge transfer processes. This work provides a green and economical method to functionalize g‐C 3 N 4 using low‐content organic carbon molecule for efficient energy conversion‐related applications.