Nanostructured FeSe thin films were deposited on glass substrates by chemical bath deposition method and the deposition time varies. The thin films are characterized by X-ray diffraction. Surface morphology of the fabricated thin films was obtained by field-emission scanning electron microscopy. In addition, atomic force microscope was employed to investigate the surface topography of the films and optical properties of films were determined by UV–Vis spectroscopy. With the increasing the deposition time the optical band gap energy of the as-deposited thin films decrease. With the FeSe thin films as photocatalyst, we decolorized two different chemical structure dyes, Congo Red (CR) and Methylene Blue (MB). A kinetic study has been performed. In addition, the heat treatment at 100 °C and 200 °C has the same behavior as well as the deposition time resulting in the shift in the optical absorption edge towards lower energy and the improvement in photocatalytic activity.
