| Since the 21st century,with the continuous advancement of industrialization and rapid economic development,environmental pollution and energy shortages have become major issues that contemporary society must inevitably pay attention to.Finding a sustainable energy conversion technology and environmental governance method has always been the research direction that scientists focus on.In this regard,photocatalytic technology,as an efficient,environmentally friendly,pollution-free and sustainable technology,has become a widespread concern of researchers,field.The traditional catalyst TiO2 is favored by people because of its stable chemical properties,low price,non-toxic and non-polluting,etc.It has always been one of the most researched photocatalysts by scientists.However,with the development of industry,people’s requirements for catalysts are getting higher and higher.TiO2 as a catalyst firstly has a low utilization rate of visible light,and secondly,its quantum efficiency is low,resulting in low catalytic efficiency,which gradually cannot meet the current social development.need.In order to overcome the shortcomings of traditional photocatalysts and improve the light absorption and conversion efficiency of catalysts,researchers turned to study multi-bandgap semiconductors Bi2Fe4O9,Fe2O3,etc.,which absorb more visible light.However,the photocatalytic efficiency of pure Bi2Fe4O9 and Fe2O3 is lower,so researchers widely use various methods such as heterojunction regulation,doping regulation,and size regulation to regulate the photocatalytic efficiency of Bi2Fe4O9 and Fe2O3.Synthetic Bi2Fe4O9,Fe2O3 catalysts often contain magnetic components,which provides a way for the recycling of the catalyst,which can significantly reduce the cost of the catalyst,so it has attracted everyone’s attention.In this thesis,by introducing ferrous ions in the hydrothermal synthesis process,we successfully synthesized ferrous ion-doped Bi2Fe4O9 nanocatalysts and catalysts in which FeOOH and Fe2O3 coexist.The research in this paper is divided into two aspects:(1)A series of Bi2Fe4O9 pure phase nanocrystals were synthesized by adding different contents of FeCl2 in the hydrothermal process,and successfully introduced lower valence iron ions into Bi2Fe4O9.The UV-Vis absorption spectrum data prove that the addition of FeCl2 reduces the optical band gap of Bi2Fe4O9 from 2.06 eV to 1.96 eV,and the reduction range reaches 0.1 eV.The scanning electron microscope photos and X-ray diffraction patterns all prove that the synthesized sample is a pure phase square sheet Bi2Fe4O9 nanocrystals.Using three Bi2Fe4O9 nanocrystal solutions with different proportions of FeCl2,the methyl orange dye solution was degraded under the irradiation of a 500W mercury lamp.It was proved that the addition of FeCl2 could improve the performance of Bi2Fe4O9 photocatalytic degradation of dye molecules when hydrogen peroxide was added appropriately.(2)Using FeCl3,sodium acetate and water as raw materials,nanoparticles with coexistence of Fe2O3 and FeOOH were synthesized by hydrothermal method.Experiments found that pure-phase iron oxide nanoparticles can be grown by adjusting the pH of the reaction solution and the amount of ferrous ions added.The photocatalytic effect of iron oxide samples synthesized under acidic and neutral conditions is poor,and alkaline conditions may be a necessary condition to increase the photocatalytic efficiency. |
