Preparation of Nano-TiO₂ Thin Film by Agar Coating Method and Its Photocatalytic Degradation Performances

Nano-TiO₂ thin films were prepared by agar coating method,and the photocatalytic properties of the prepared TiO₂ thin films were studied.The thin films were characterized by XRD,BET,FESEM,FTIR,EDX and UV-Vis DRS.The results show that the crystal size of TiO₂ prepared by agar coating can be reduced to 20 nm,while the crystal size of TiO₂ prepared by common sol-gel method is about 30 nm.The surface images show that the nano-TiO₂ thin films prepared by agar coating are uniformly distributed and have uniform morphology without crack.The results of UV-Vis DRS show that the bandgap of TiO₂ is reduced by adding agar,and the removal efficiency of methylene blue by the prepared TiO₂ is 71% in 120 min.The activity of TiO₂ remains at high level after 5 cycles of methylene blue treatment.The formation mechanisms of coating of nano-TiO₂ are also discussed based on the reaction characteristics.