Regulating Polymerization in Graphitic Carbon Nitride To Improve Photocatalytic Activity

Polymeric graphitic carbon nitride (g-CN) has emerged as a promising metal-free photocatalyst; however, the polymerization process is still poorly understood, and the synthesized g-CN shows a structural complexity, with photocatalytic activities far from being optimized. Herein we present new insight into its polymerization reaction kinetics and develop a quasi-sealed condensation route to properly regulate the distribution of the degree of polymerization (DP) in the synthesized g-CN. The correlation throughout the condensation process, the structure–property relationship, and the photocatalytic performance of g-CN have been discussed in detail. The synthesized g-CN shows a narrower and uniform DP distribution, possesses improved crystallinity, and features a nanoporous texture with fruitful amine groups and better water dispersibility, which promotes the fast charge-carrier transport under aqueous conditions and give rise to substantially enhanced photocatalytic activity. Compared with the conventional counterpart, its visible-light activity is 4.88 times higher for hydrogen production, 7.81 times higher for the degradation of rhodamine B, and 2.47 times higher for the degradation of 4-chlorophenol. We further report that its solar-driven photocatalytic activity is superior to that of the representative Degussa TiO2 P25 catalyst for scale-up RhB degradation, thus highlighting the great prospects of g-CN-based photocatalysts toward practical applications.