Preparation And Modification Of BiOCl Materials Based On Bismuth Glass

In recent years,with the rapid development of industrialization,energy shortages and environmental pollution have become the two most important issues.Photocatalytic technology is considered to be one of the most promising technologies.It can convert low-density solar energy into high-density chemical energy,and degrade pollutants in water through photocatalytic reactions.Bismuth oxychloride(BiOCl)material is considered to be a promising photocatalytic material due to its high chemical stability,unique layered structure and good corrosion resistance.However,BiOCl with wide band gap(3.2e V-3.5e V)can only absorb ultraviolet radiation,which limits its photocatalytic performance.Therefore,It’s necessary to modify BiOCl photocatalysis to improve its visible light activity.It is well known that glass has a loose network structure,which is formed after high temperature melting and extraction cooling,which can retain defects at high temperatures.As an important strategy for photocatalyst modification,oxygen vacancies(OVs)can adjust the energy band structure of the photocatalyst to expand its light absorption range.In addition,it can also be used as an electron trap site to improve the separation efficiency of electron/hole pairs.In this paper,BiOCl photocatalytic material with oxygen-rich vacancies was prepared by using bismuth glass as the bismuth source for the degradation of rhodamine B(Rh B)dye.And the morphology of the catalyst,crystal structure,photoelectric properties and photocatalytic performance was systematically studied by a variety of characterization methods.Our research content mainly includes the following aspects:First,three different kinds of bismuth glass was used as raw materials,and BiOCl materials was obtained after one-step water bath reaction.By adding strontium oxide and sodium oxide on the basis of the original bismuth-boron-zinc glass system,the network external bodies such as strontium oxide and sodium oxide have the effect of destroying the glass skeleton,so that the glass can form more oxygen defects.Therefore,after the photocatalyst is exposed to light,the presence of oxygen vacancies makes the BiOCl photocatalytic material expand to the visible light range,and as a site for trapping electrons,it further improves the electron/hole separation efficiency of BiOCl to promote the photocatalytic performance.Second,based on the first step,the photocatalytic activity of BiOCl materials prepared from different bismuth glasses was compared.Therefore,in this chapter,we chose BBZSN as the bismuth source by controlling the morphology of BiOCl with different forms of intermediates and halogen sources to prepare futon-like,flower-like,sheet-like and bundle-like structures,respectively.It is well known that morphology affects the photocatalytic performance of materials.This is due to the different specific surface areas of BiOCl materials with various morphologies,so the adsorption capacity for dyes is also different.In addition,the 3D structure formed by the self-assembly of nanosheets can promote the diffusion of reactants in photocatalytic materials.This is because materials with a hierarchical structure are rich in mesopores and macropores,which are easy to contact and react with the active sites on the surface of the photocatalytic material,and light will undergo multiple scattering and light reflection in the irregular pores formed by the photocatalytic material,resulting in a longer trip and an increase in the number of absorptions,so the photocatalytic material will absorb more light.From the above points,it can be seen that the morphology plays an important role in the photocatalyst.Finally,in order to further expand the visible light absorption range of photocatalytic materials,we synthesized BiOCl1-x Brx solid solution through a two-step method using Sodium chloride(Na Cl)and Sodium bromide(Na Br)as halogen sources through a solid solution method.The formation of solid solution also changes the energy band structure of the material to a lower valence band position,which is conducive to the generation of holes and oxygen-active groups.Therefore,the best photocatalyst activity can be achieved under a certain ratio of Cl~-and Br~-.In the experimental results,the BiOCl0.6Br0.4 material showed the best performance,and the degradation efficiency of the dye rhodamine B reached 92.5%/40min.