Synthesis of Pb-substituted LaCoO3 nanoparticles by microwave process and their photocatalytic activity under visible light irradiation.

In this study, nanosized lead-substituted perovskite type oxides, La1_xPbxCoO3, were successfully synthesized using a microwave-assisted method and characterized by TG/DTA, XRD, XPS, TEM and DRS. We also investigated the photocatalytic activity of these oxides for the decomposition of methyl orange. From XRD results, metal replacement with the Pb ion in the crystal lattice does not change the high crystallinity of the perovskite structure. When Pb ions are substituted into site A, the particle size decreased when compared to lead-free LaCoO3 perovskite type oxide. In the of UV-Vis DRS analysis, all the catalysts displayed the similar absorption spectrum up to the visible region and the absorption band shifted to a higher wavelength on the lead-substituted LaCoO3 perovskite oxides when compared to the lead-free LaCoO3 oxide. From XPS results, chemisorbed oxygen was shown to play an important role in the photocatalytic decomposition of methyl orange and the higher chemisorbed oxygen content, the better the performance of the photocatalyst.