Hollow spherical g-C3N4 rich in cyano groups for efficient adsorption and photodegradation of methylene blue

Graphitic carbon nitride (g-C₃N₄) hollow microspheres are prepared by thermal condensation of melamine using CaCO₃ microspheres as template. CaCO₃ template not only ensures the construction of the hollow structure of g-C₃N₄, but also promotes the formation of a large number of cyano groups. The hollow micro-spherical structure of the g-C₃N₄ significantly increases its specific surface area, while the abundant cyano groups promote its ability to separate and transfer charges, thereby achieving a dual effect of morphology control and surface functionalization through a single strategy. As a model substrate, methylene blue(MB) is used to evaluate the photocatalytic performance of the g-C₃N₄. It reveals that these g-C₃N₄ hollow microspheres have both high adsorption and high degradation capabilities for MB. Even for a MB solution with concentration as high as 160 mg/L, which is ~ 8 times of those used in most literature, the g-C₃N₄ exhibits a photodegradation efficiency of ~ 94.3% in 1 h. Compared with the traditional method for preparing g-C₃N₄ hollow microspheres using SiO₂ microspheres as template, the method reported in this work is simpler and more environmentally friendly, which is expected to lay the foundation for the large-scale application of such materials in the future.