High yield post-thermal treatment of bulk graphitic carbon nitride with tunable band structure for enhanced deNO_x photocatalysis

The bulk graphitic carbon nitride (CN) suffers from low specific surface area, which limits its practical application for air purification. Here, we reported a facile post-thermal treatment to break bulk CN into nanosheets whose specific surface areas increased from 13.6 m² g^-1 to 68.0 m² g^-1. The yield of CN nanosheets reached up to 67%, and its photocatalytic decomposition of NO_x activity was about 3.0 times higher than that of bulk CN. Moreover, the CN nanosheets obtained at 550 °C with higher specific surface area (113.9 m² g^-1) displayed lower photocatalytic activity than that obtained at 500 °C with lower specific surface area (68.0 m² g^-1), which was attributed to its lower valence band. This study illustrates that many factors including specific surface area and band structure could affect the performance of photocatalysts so that it is necessary to take account of various factors. Moreover, the facile and high yield thermal treatment provides the foundation for further large-scale industrial applications.