Rapid high-temperature treatment on graphitic carbon nitride for excellent photocatalytic H₂-evolution performance

Graphitic carbon nitride is considered as one of the most potential photocatalysts for utilizing solar energy. Herein, an efficient route of rapid high-temperature treatment (at 800 °C in air for 0–20 min) was developed to modify pristine graphitic carbon nitride. It was found that, after rapid high-temperature treatment, the obtained photocatalysts showed greatly enhanced photocatalytic H₂-evolution activities (around 25.5 times) under visible-light irradiation attributed to the following reasons. More active sites for photocatalytic reaction were provided by the significant increase of surface areas. The generation, separation and transfer of photo-generated carriers were effectively promoted by the quantum confinement effect of thinner graphitic carbon nitride sheets and by the generated nitrogen vacancies in C–N heterocyclic units. Moreover, stronger driving force for photocatalytic H₂-evolution reaction was obtained to enhance the ability of water reduction reaction.