Embedding an organic dye into Ti-MCM-48 for direct photocatalytic selective aerobic oxidation of sulfides driven by green light

Ti-containing mesoporous silica materials with a well-defined structure could give a clear picture of the elusive reaction pathways in photocatalysis. However, the dispersion of Ti sites usually results in their bandgaps being larger than that of TiO 2 , which makes the narrowing of bandgaps more challenging to construct visible light photocatalysis. Here, Ti-MCM-48 with an ordered cubic mesostructure and a homogeneous dispersion of Ti sites were successfully synthesized to embed an organic dye alizarin red S (ARS), affording a visible light photocatalyst ARS – Ti-MCM-48. The selective aerobic oxidation of sulfides into sulfoxides driven by green light over ARS – Ti-MCM-48 was accomplished directly. Notably, both electron transfer and energy transfer pathways were involved in the activation of O 2 , in which the Ti sites play a crucial role. Importantly, the photobleaching was effectively alleviated by embedding ARS into the mesopores of Ti-MCM-48. Moreover, high selectivities of desired sulfoxides were favorably achieved. In general, Ti-containing porous materials could be a unique scaffold for embedding photoactive molecules to carry out selective organic transformations driven by visible light.