Synthesis And Photocatalytic Activity Investigation Of YMnO₃ And YMn₂O₅ Nanoparticles

The preparation and catalytic activity of photocatalysis materials have attracted much attention, especially some catalytic materials could respond the visible light, which becomes one of focuses and frontiers in the field of catalysis. Due to the continuous development of nanotechnology, some materials in nanometer scale will show more excellent properties than block materials. At present, the researchs of photocatalytic activity of perovskite nanostructured materials is still in a exploration stage, many performances of them still need further research.In the dissertation, YMnO3 and YMn2O5 nanoparticles were synthesized and their photocatalytic activity was investigated, the results obtained are listed as follows:1. YMnO3 nanoparticles was investigated of the preparation and photocatalytic activity. The as-synthesized YMnO3 nanocrystallites majorly into a hexagonal perovskite structure and minorly into an orthorhombic perovskite structure without the presence of any other impurities by a polyacrylamide gel technique, in which Y(NO3)3.6H2O and Mn(CH3COO)2.4H2O was used starting materials, EDTA as Chelating agent.In the solution, N,N'-methylene-bisacrylamide were added with different ratio from acrylamide, bisacrylamide plays an important role in tailoring the particle size. It is noted that a slight increase in the bandgap with the decrease in particle size,the Eg is changed from 1.23 to 1.31 ev. The photocatalytic experiments reveal that the as-prepared YMnO3 nanoparticles exhibit a pronounced photocatalytic activity for the decomposition of methyl red under ultraviolet and visible light irradiation, and the photocatalytic efficiency increases with decreasing the particle size. The optimum conditions for the photocatalytic decolorization were determined to be as follows:catalyst dosage,1.5 g/L.2. YMn2O5 nanoparticles was investigated of the preparation and photocatalytic activity.The as-synthesized YMn2O5 nanoparticles majorly into orthorhombic YMn2O5 phase and minorly into hexagonal YMn2O5 phase without the presence of any other impurities by a polyacrylamide gel technique, in which Y(NO3)3.6H2O and Mn(CH3COO)2.4H2O was used starting materials, Citric acid as Chelating agent. Change chelating agent for EDTA, it plays an important role in tailoring the particle size. Ultraviolet-visible diffuse reflectance spectroscopy was used to investigate the light-absorbing properties and bandgap of YMn2O5 nanoparticles, and the value of the optical bandgap energy is obtained to be 1.21 and 1.17 eV respectively. The photocatalytic activity of YMn2O5 nanoparticles was investigated by the degradation of Methyl red (MR), a typical azo dye. The optimum conditions for the photocatalytic decolorization were determined to be as follows:initial concentration of MR,15 mg/L; catalyst dosage,1.2 g/L.