Dye Degradation Activity and Stability of Perovskite-Type LaCoO3-x (x=0∼0.075)

Perovskite-type LaCoO3-x(x = 0 similar to 0.075) porous powder was synthesized via citrate sol-gel method. With calcination temperature increasing, its crystal structure changed from LaCoO3 to LaCoO2.925 with the increase in oxygen vacancy. The synthesized LaCoO3-x contains a large amount of adsorbed oxygen on its surface due to the existence of oxygen vacancy to some extent. Dye degradation activity of LaCoO3-x in methyl orange solution was investigated both under the visible light irradiation (>400 nm) and in the dark. LaCoO3-x exhibited dye degradation activity in the dark when being preserved in methyl orange solution for a long time caused by the reducibility of Co3+ in LaCoO3-x, and then dye molecule was oxidized gradually and slowly. The degradation rate was improved tinder the visible light due to the optical property of LaCoO3-x in visible light region. After degradation, methyl orange molecule may be decomposed to acetate group in a small amount. After use for a long time, some Co3+ was reduced to Co2+ accompanied by the formation of oxygen vacancy, and then LaCoO3 transformed to LaCoO2.925 gradually. For LaCoO3-x calcined at 800 degrees C, LaCoO3-x perovskite skeleton structure was stable, and can be reused in recycle dye degradation. [doi:10.2320/matertrans.M2010200]