Preparation, Modification And Photocatalytic Property Of Ultrafine Perovskite-type PrMnO₃

Using rare earth oxides, rare earth carbonate and transition metal nitrates as raw material, the series dry-gels ultrafine PrMnO₃ and doped-PrMnO₃ were prepared by sol-gel method conbining with vacuum drying method. The matirials prepared were characterized by TG-DTA, XRD, TEM and FT-IR. The photocatalytic activity was test by photocatalysis degrading methyl orange solution in the system of PrMnO₃ suspension, irradiated under ultraviolet lamp. The results show:(1) Pr-Mn dry-gel is mainly armorphous after drying at 170℃, and the component of crystal may be PrO(OH). In the process of thermal treating, Pr6O11 and Mn₂O₃ appeared at 500℃and 700℃respectively. The crystallization process of manganese oxide is affected by Pr. At 900℃, the crystal component of dry-gel is single perovskite-type PrMnO₃ with well crystallinity.(2) Dry-gels are made up of a mass of spherical grains whose diameter is uniform about 10-20nm. In the process of thermal treating, the particle size increases because of agglomeration which is resulted from dehydration. The size is about 50-100nm at 900℃.(3) Because A-site cation defects were resulted by Ce, Nd and Fe doping, photocatalytic activities of PrMnO₃ were enhanced. The photocatalytic activities were enhanced more after Co doped, which substituted part of Mn as B-site cation. The Conduction Band was made up by Co and Mn cation, so the photocatalyst is easier to be excitated by light. The crystal parameter and volume of perovskite-type PrMn_1-xCo_xO_3+λ(x=0.1,0.2,0.3,0.4) minish with x.(4) Then, reaction of photocatalytic degradating methyl orange with PrMnO₃ series as photocatalyst followed first order kinetics.