A photocatalytic comparison study between tin complex and carboxylic acid derivatives of porphyrin/TiO2 composites

We synthesized a novel dihydroxotin(IV) porphyrin complex with full structural confirmation. The tin complex further converted to TiO 2 composite ( PR-2–TiO 2 ) and photodegradation of methylene blue property compared with carboxylic-anchored porphyrin photocatalyst ( PR-3–TiO 2 ), basic porphyrin photocatalyst ( PR-1–TiO 2 ) and bare TiO 2 . PR-1–TiO 2 showed slight photocatalytic activity, which was better than that of bare TiO 2 . The photocatalytic performances of tin-porphyrin ( PR-2–TiO 2 ) and carboxylic anchor porphyrin ( PR-3–TiO 2 ) were comparable, and tin-porphyrin catalyst showed similar stability in their reusability test result in comparison with carboxylic-anchored porphyrin catalyst. Finally, we showed a plausible structure for the tin porphyrin complex between the axial –OH ligand and TiO 2 and a suitable mechanism with theoretical comparison for the photocatalytic process. Graphic abstract