Preparation And Visible-light Photocatalytic Performance Of Porous Cu/Cu₂O And Cu/Cu₂O/SnO₂ Films

Cu2O is an important semiconductor photocatalytic material with the band gap about 2.0eV. It could be triggered photocatalytic reaction under sunlight irradiation. Cu2O is considered as a promising material used in solar cells, photochemical batteries, photocatalysts and so on.In this thesis, using hydrogen bubbles as dynamical templates, porous Cu films have been electrodeposited on the substrates of 304 type stainless steel foils. Porous Cu/Cu2O films were obtained by low-temperature oxidating in air. The porous Cu/Cu2O/SnO2 films were obtained through dip-coating the porous Cu films in a self-made SnO2 sol followed by heated in air. The photocatalytic activities and stabilities of the two porous films were tested by using photodegradation performance of rhodamine B (RhB,3 mg/L,10 mL) in aqueous solution under visible light irradiation(λ>380 nm). The films were characterized with scanning electron microscopy(SEM), Transmission Electron Microscope(TEM), X-ray diffractometry(XRD), UV-Vis diffuse reflectance spectroscopic(UV-Vis DRS) and Fluorescence Spectrometer(FS). The effect of the preparation parameters on morphologies, structures, constitutes and photocatalytic performances of the films were investigated in detail. According to the variation of their optical properties, the photocatalytic reaction mechanisms of the films were discussed. The main works are as follow:1. Porous Cu films were electrodeposited in the solution containing 0.2 mol/L CUSO4, 1.5 mol/L H2SO4 at 30℃at 1.5 A/cm2, by using hydrogen bubbles as dynamical templates, for 20 s. Porous Cu/Cu2O films were obtained by heating the porous Cu films at 100℃for 30 min in air. The photocatalytic performances of the Cu/Cu2O films were tested through photodegradation of RhB illuminated with visible light. The results of SEM, XRD and TEM reveal that the porous films constructed with submicro particles of Cu core-Cu2O shell structured. The ratio of RhB degradation is 91.4% after 60 min of the irradiation for the films first time used. And the ratio remained above 60% after tested 5 times. It shows higher activity and stability for photocatalytic degradation of RhB under visible light irradiation.2. The dip-coating method was used to coat the SnO2 on the porous Cu films in a self-made SnO2 sol. The influence of the layers of SnO2 coated as well as temperature and time of heated on the photocatalysis activity of the films were studied. The result shows that the porous Cu/Cu2O/SnO2 films with the highest activity could be obtained through coated 5 times SnO2 on the porous Cu films then heating at 100℃for 30 min in air. The ratio of degradation of RhB is 98.4% for the films first time used after 60 min of the irradiation. And the ratio of degradation remained nearly 80% after tested 15 times. The porous Cu/Cu2O/SnO2 films show higher photocatalysis activity and stability than porous Cu/Cu2O films for photocatalytic degradation of RhB under visible light irradiation.3. The results of UV-Vis DRS analysis show that the absorption edges of two films are at 600 nm. The absorption of the porous Cu/Cu2O/SnO2 films is enhanced by compared with the porous Cu/Cu2O films. The results of FS reveal that two films both exhibit strong fluorescence emission spectra. And photoluminescence (PL) intensity of the porous Cu/Cu2O/SnO2 films is also stronger than that of the porous Cu/Cu2O films, which is consistent with the photocatalytic activities of the films.