The Effect Of Rare Earth Doping On The Structure And Properties Of Ruthenium-based Photocatalysts

Semiconductor photocatalytic oxidation technology has promising application in environmental protection and water treatment because it can use solar light to deeply oxidize organic pollutants.Bi-based photocatalyst has become a hot spot in the field of photocatalytic research because of its suitable band gap and environment friendly.Rare earth element has rich energy levels and the special 4f electronic structure,so it can become an important dopant.There have been many reports about rare earth doped Bi-based photocatalyst,but the reports about rare earth co-doped or rare earth and non-mental co-doped Bi-based photocatalyst are relatively rare.In this dissertation,rare earth co-doped Bi₂O₃ and BiVO₄ photocatalysts were first developed.Then further research was focused on the effects of rare earth and nonmetal co-doping on the structure and photocatalytic performance of Bi-based semiconductors.The main research contents are as followings:First,a series of La or/and Ce doped Bi₂O₃ composite photocatalysts were fabricated by the hydrothermal process.La and Ce doping induced crystal phase transformation in Bi₂O₃,from monoclinic to tetragonal phase.Moreover,La and Ce codoping induced the grain refinement of Bi₂O₃,increased the specific area and improved the degree of dispersion.Moreover,the synergistic effects of La and Ce codoping effectively suppress the recombination of photo-generated electrons（e-）and holes（h+）.Therefore,the superior photocatalytic performance was obtained over the（3/1）La/Ce-codoped Bi₂O₃ samples.Second,a series of La or/and Gd doped BiVO₄ composite photocatalysts were fabricated by the hydrothermal process.La and Gd doping induced crystal phase transformation in BiVO₄,from monoclinic to tetragonal phase and the increase in the surface area.The rare earth doping can improve the photocatalytic properties of BiVO₄.Therefore,the superior photocatalytic performance was obtained over the（4/1）La/Gd codoped BiVO₄ samples.Third,Eu,F-codoped BiVO₄ microspheres with the diameter of 1-3 μm were successfully fabricated via a hydrothermal route.It was found that the presence of F increased the crystallinity and the presence of Eu induced crystal phase transformation（from monoclinic to tetragonal phase）,the formation of microsphere morphology and the increase in surface area.The separation of photo-generated electrons（e-）and holes（h+）was also promoted by F and Eu doping.The improvement in texture property and the promoted separation efficiency of the photo-generated electrons（e-）and holes（h+）could mainly contribute to the superior photocatalytic activity over Eu,F-codoped BiVO₄ microspheres.The above research results indicated that rare earth co-doped or rare earth and nonmental co-doped could change the crystal structure of Bi-based photocatalyst and promote the separation of photo-generated electrons（e-）and holes（h+）,then greatly improving the photocatalytic performance of Bi-based on organic dyes.