Photocatalytic property of Cu2+-doped Bi2O3 films under visible light prepared by the sol–gel method

• Cu2+-doped Bi2O3 films were prepared by sol–gel method on a glass substrate.
• The absorption peaks of the Cu2+-doped Bi2O3 films moved to longer wave-lengths in comparison with the undoped Bi2O3 films.
• Photocatalytic activity under visible light irradiation was improved by adding Cu2+ ions into the films.

The Cu2+-doped Bi2O3 films were prepared by the sol–gel method on a glass substrate. X-ray diffraction, atomic force microscopy techniques and spectrophotometry were applied to characterize these films. It was found that, compared with the undoped Bi2O3 film, the absorption peaks of the Cu2+-doped Bi2O3 films moved to longer wave-lengths. The visible light photocatalytic activities were evaluated by photodegradation of Rhodamine B. The results showed that photocatalytic activity under visible light irradiation was improved by adding Cu2+ ions into the films. When the molar ratio of Cu/Bi was 5/500, the sample showed the highest photocatalytic efficiency (96% at 120 min). The enhanced photocatalytic activity might result from the narrowed band-gap and effective separation of photogenerated electron/holes caused by Cu2+ doping.