Defect-Induced Activity Enhancement of Self-Exfoliated Carbon Nitrides for Solar Hydrogen Evolution

The recombination of photogenerated electron-hole pairs severely limits the efficiency of solar-driven hydrogen evolution in carbon nitrides (CN) system. Herein, a K+ doped and cyanamide defects modified CN (CCNK) with free-standing nanosheets in water was synthesized by a bottom-up self-exfoliated strategy. Further experimental characterizations reveal that the cyanamide moiety and K+ in the framework play an important role in the enhancement of hydrophilicity and efficiently suppress electron-hole pair recombination. CCNK exhibits an impressive photocatalytic hydrogen evolution activity (132.6 mu mol h(-1)), which is 22 times higher than bulk CN (6.0 mu mol h(-1)), and far surpassing other CN-based photocatalysts. This work provides an innovative facile self-exfoliated strategy for bottom-up preparation of ultrathin CN nanosheets without using any acid, base, or solvents, paving the way for the development of high-performance photocatalysts using CN-based powders.

Automated summary

A K+-doped and cyanamide defects modified carbon nitride (CCNK) with free-standing nanosheets in water was synthesized using a bottom-up self-exfoliated strategy. The cyanamide moiety and K+ in the framework play a crucial role in enhancing hydrophilicity and efficiently suppressing electron-hole pair recombination. CCNK exhibits impressive photocatalytic hydrogen evolution activity (132.6 µmol h(-1)), which is 22 times higher than bulk carbon nitride (6.0 µmol h(-1)), surpassing other carbon nitride-based photocatalysts. This work provides a innovative facile self-exfoliated strategy for the preparation of ultrathin carbon nitride nanosheets and paves the way for high-performance photocatalysts using carbon nitride-based powders.