Higher-than-common temperature short-time processed polymeric carbon nitride nanosheets as an efficient photocatalyst for H2 production

Two-dimensional polymeric carbon nitride nanosheets exhibiting unique optical properties are considered promising materials for visible light active photocatalysts. Here, we synthesized thin polymeric carbon nitride nanosheets via the higher-than-common temperature (710 °C) pyrolysis of a polymeric carbon nitride intermediate for 20 min. The exfoliation efficiency of the nanosheets was dramatically improved by the higher-than-common temperature treatment. Notably, compared with the pristine polymeric carbon nitride nanosheets, the synthesized thin polymeric carbon nitride nanosheets exhibited a reduced optical bandgap and more negative conduction band (ECB) positions, which ensured enhanced visible-light absorption and reductive ability. When applied to photocatalytic water-splitting reaction for H2 evolution, the thin polymeric carbon nitride nanosheets exhibited enhanced activity under visible light irradiation, accounting for an optimal H2-evolution rate of 8187 µmol·g−1·h−1 with a Pt loading of 1 wt%, which was approximately six-fold higher than that obtained with the urea-derived pristine polymeric carbon nitride nanosheets. This work provides a rapid, affordable and facile method for synthesizing polymeric carbon nitride nanosheets with high photocatalytic performances. •The short-time pyrolysis strategy can synthesize thin polymeric carbon nitride nanosheets (PCN-710) efficiently.•PCN-710 nanosheets possess both enhanced visible light absorption and charge mobility.•PCN-710 nanosheets demonstrate large specific surface area that can provide more active sites for rapid surface reactions.•PCN-710 nanosheets exhibit notable photocatalytic hydrogen evolution activity under visible light irradiation.