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

Construction of nitrogen deficient graphitic carbon nitride with heptazine/triazine feature to boost photocatalytic hydrogen evolution. [Display omitted] •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-1h−1, which was 8.12 times than bulk g-C3N4.•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-C3N4) 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-C3N4 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-C3N4 exhibited more negative band edge potential and faster charge carrier transfer, which was superior to undoped g-C3N4. The photocatalytic hydrogen production rate of nitrogen deficient crystalline g-C3N4 was boosted to 569.5 μmol g-1h−1, which was 3.44 and 8.12 times higher than undoped g-C3N4 and bulk g-C3N4. 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.