Study On The Influence Of Doping On The Photocatalytic Activity Of Perovskite-Type Oxides ABO₃

ABO₃ perovskite type complex oxides and their doped compounds were prepared by citrate method. The type was proved by XRD. The formation mechanism of LaMnO₃ prepared by citrate method was analyzed by TG-DTA thermo analytical means, with the spectrum of IR and XRD. The mechanism can be stated as follows:Some samples were proved to be nanocrystalline by TEM technique. Using a 450W Hg lamp as irradiator, the photodegradation experiments of various water-soluble dyes were carried out in the suspension system of ABO₃ perovskites acting as photocatalysts, and the decolorizing rates would be considered as the reflection of the photocatalytic activity.With SEM, TEM, IR, UV-Vis, XPS and photoacoustic spectrum, we could more study the factors influencing the photocatalytic activity. The results show that (a) with the rise of Allred-Rochow electronegativity of the elements (A, B) and the increase of d-electron number of ion B, the charge-transfer energy (â–³CT) between O2p and B3d decreases, so that the photocatalytic activity of ABO₃ increases; (b) the perturbation of doping can greatly improve the photocatalytic activity because of the role of the localized energy and the oxygen vacancy which can appreciably improve wavelength response and increase the amount of the absorbed oxygen; but with the increasing of quantity of doping, the arrangement of oxygen vacancy was ordered locally and the activity was decreased, so that there was a best doping quantity.