Tunable heptazine/triazine feature of nitrogen deficient graphitic carbon nitride for electronic modulation and boosting photocatalytic hydrogen evolution

Abstract

Construction of nitrogen deficient graphitic carbon nitride with heptazine/triazine feature to boost photocatalytic hydrogen evolution • Nitrogen deficient graphitic carbon nitride with tunable heptazine/triazine feature was constructed. • The photocatalytic hydrogen production rate of CCN-10% was boosted to 569.5 μmol g -1 h -1 , which was 8.12 times than bulk g-C 3 N 4 . • CCN-10% showed an enhanced surface area, light harvesting and photogenerated charge separation capacity. • CCN-10% showed preferable reusability and durability. Graphitic carbon nitride (g-C 3 N 4 ) as metal-free semiconductor was a fascinating photocatalyst for hydrogen production, suffering from fast charge recombination due to incomplete polymerization. In this regard, nitrogen deficient crystalline with tunable heptazine/triazine feature was obtained. It’s found that incorporation of 2,4-diamino-6-hydroxypyrimidine into g-C 3 N 4 framework and the subsequent molten salt re-polymerization process led to nitride deficient feature and maneuverable tuned heptazine/triazine units, resulting the band gap red shift from 2.53 to 2.08 eV with broadened band tail in the range of about 480-800 nm. Careful characterizations revealed that nitrogen deficient crystalline g-C 3 N 4 exhibited more negative band edge potential and faster charge carrier transfer, which was superior to undoped g-C 3 N 4 . The photocatalytic hydrogen production rate of nitrogen deficient crystalline g-C 3 N 4 was boosted to 569.5 μmol g -1 h -1 , which was 3.44 and 8.12 times higher than undoped g-C 3 N 4 and bulk g-C 3 N 4 . Besides, the apparent quantum efficiency of optimal catalyst was obtained 10.71% at 435 nm. This work may offer a useful route to fabricate tunable heptazine/triazine-based carbon nitride photocatalyst for hydrogen production.