The application of Fe–TiO2 photocatalysis using sol–gel method by hot–dipping technique was investigated. Then, the influences of fabrication parameters, molar ratios of Fe to TiO2, the sol temperature, poly ethylene glycol (PEG) content and the number of dipping cycles on the photocatalytic activity in visible light region were mainly studied. The experimental results revealed the sample with the molar ratios of Fe to TiO2: 0.015, the sol temperature: 70 °C, PEG content: 2 wt. % and the number of dipping cycles: 5 showed the best result. The photodegradation efficiency of this sample after 2 h visible light irradiation increased up to 80% and no crack was detected on the surface of the thin film. When the sol temperature increased from 25 to 70 ºC (the boiling point of the sol), its viscosity increased due to the existence of PEG via forming cross linkage. This phenomenon caused to change the microstructure and improve in optical properties. پرونده مقاله