Photocatalytic property of Cu²⁺-doped Bi₂O ₃ films under visible light prepared by the sol-gel method

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 Bi₂O ₃ 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.