The invention discloses a method for preparing a
samarium-doped
titanium dioxide thin film, which comprises: mixing
butyl phthalate and absolute
ethanol to obtain
mixed solution, and adding diethanol amine into the
mixed solution to obtain solution A; uniformly mixing deionized water, diacetone and absolute
ethanol to obtain solution B; adding the solution B into the solution A, regulating the pH value to 2.0 to 5.0 by using
hydrochloric acid, magnetically stirring and aging to obtain gel C; soaking a cleaned substrate into the gel C, standing, lifting,
coating a film and
drying; and annealing the dried thin film to obtain the
samarium-doped
titanium dioxide thin film. In the invention, the
reaction temperature is low, the production efficiency is high, the raw materials are readily available, the operation is simple, the coated film is uniform and the
repeatability is high. The organic degradation catalyzing capacity of the prepared thin film under
irradiation by
sunlight is much higher than that of
titanium dioxide thin films. By controlling the doped amount of
samarium, the thin film having much higher photocatalytic effect than
titanium dioxide thin films can be prepared, and the rate of
methyl orange decolorization catalyzed by the thin film reaches 10 to 70 percent.