Low boiling point solvent mediated strategy to synthesize functionalized monolayer carbon nitride for superior photocatalytic hydrogen evolution

[Display omitted] •A process of low boiling point solvent was adopted to pretreat the urea.•Functionalized monolayer g-C3N4 was obtained via calcining the pretreated urea.•Charge transfer and separation from both in-plane and interlayers can be enhanced.•CN-acetone presents superior photocatalytic H2 evolution performance.•The photocatalytic mechanism was proved by experimental and theoretical analyses. Graphite carbon nitride (g-C3N4) is a promising photocatalyst, but its efficiency for photocatalytic hydrogen (H2) evolution is still limited owing to its spatial charge separation. Herein, a functionalized monolayer carbon nitride photocatalyst with carbon vacancies and rich amino groups was synthesized via facile thermal induced exfoliation and polycondensation assisted by low boiling point of solvents. Experiments and calculations unveil that introducing carbon vacancies and rich amino groups into monolayer CN-acetone narrowed diffusion distance of photogenerated carriers and effectively enhanced their separation. Therefore, CN-acetone exhibited an outstanding photocatalytic H2 evolution performance with a rate of 29.33 mmol h−1 g−1 (AQY = 26.2%), a 16-fold higher than that of pristine g-C3N4 under 420 nm light irradiation. The present work opens a new window for fabricating carbon nitride photocatalysts with high performance for photocatalytic H2 evolution.