Growth of g-C₃N₄ on mesoporous TiO₂ spheres with high photocatalytic activity under visible light irradiation

Growth of graphitic carbon nitride on mesoporous TiO₂ spheres with well-controlled structures was achieved by melt-infiltrating dicyandiamide (DICY). The molten DICY diffused into the porous structure of TiO₂, and g-C₃N₄ was produced inside the mesopores formed by packing of TiO₂ nanoparticles at higher temperature, resulting in a better fused g-C₃N₄-TiO₂ heterostructure. The formation of a strong interfacial connection between TiO₂ and g-C₃N₄ by this preparation method greatly improved the separation efficiency of photo-generated electrons and holes. TiO₂/g-C₃N₄ composites exhibited much higher photocatalytic activity than TiO₂ and g-C₃N₄ towards the degradation of Rhodamine B under both UV light and UV-vis light irradiation. The heterostructured combination provided a synergistic photocatalytic activity through an efficient electron transfer process. Based on the experimental results, a possible mechanism for the improved photocatalytic performance was proposed. The factors affecting the photocatalytic activity were also discussed based on the result of structure analysis, optical and photoelectric characteristics, and photocatalytic reactions.