Preparation And Properties Of Bismuth Oxyhalide Composite Photocatalytic Paper

Nature is severely affected by environmental pollution and energy problems,and photocatalytic degradation of target pollutants is a new and efficient technology for environmental pollution degradation and control technology.Photocatalytic technology can use the sun to remove harmful pollutants in water and air.Harmful substances are degraded into inorganic molecules such as water and carbon dioxide.Photocatalytic technology has the advantages of environmental friendliness and no secondary pollution.Research in recent years has found that BiOX(X=Cl,Br,I)semiconductor material has its own unique electronic structure and good visible light response range,so it shows great potential in photocatalytic degradation of pollutants.In this paper,BiOX was deposited on pulp fibers(PFs)by in-situ synthesis.The results show that photocatalytic paper has the best formaldehyde removal rate,formaldehyde removal rates of BiOBr/PFs,BiOI/PFs and BiOCl/PFs photocatalytic paper were 74.9%,75.3%and 60.8%when the amount of bismuth nitrate added is 0.0045 mol/L.BiOBr/PFs and BiOI/PFs have better photocatalytic activity than BiOCl/PFs photocatalytic paper.However,BiOX single component photo-generated electrons and holes are easy to recombine,and its own stability is poor.The purpose of the following research is to build a BiOX composite photocatalytic paper material with high catalytic activity and good photocatalytic stability.Using the same preparation method described above,BiOBr/BiOI/PFs composite photocatalytic paper was prepared by changing the synthesis ratio of BiOBr and BiOI.Under visible light 4 h,photocatalytic activity of composite photocatalytic paper is demonstrated by the degradation rate of formaldehyde pollutants.The effects of reaction sequence,reaction time,and BiOI synthesis ratio on the photocatalytic performance of BiOI/BiOBr/PFs composite photocatalytic paper were investigated.Studies have shown that the formaldehyde degradation rate of 60%BiOI/BiOBr/PFs composite photocatalytic paper is 88.1%,the degradation rate of formaldehyde for three cycles was 76.6%,photocatalytic activity and cycle stability are higher than BiOBr/PFs,BiOI/PFs photocatalytic paper.BiOBr and BiOI are nested structure.This structure is not conducive to the effective separation of photo-generated carriers.BiOI/BiOBr/PFs composite photocatalytic paper is exposed to visible light.The band structure of both BiOI and BiOBr changed from the previous nested type to the interleaved type.This structure can improve the visible light absorption capacity of the composite photocatalytic paper and effective electron transfer reduces the chance of photo-generated electrons and holes recombining.By changing the concentration of the silver nitrate solution,AgX/BiOX/PFs composite photocatalytic papers with different AgX mass percentages were prepared,the reaction conditions remain unchanged.The photocatalytic activity of AgBr/BiOBr/PFs,AgI/BiOI/PFs composite photocatalytic paper is better than that of single-component photocatalytic paper.When AgX loading is 10%,the formaldehyde degradation effect of composite photocatalytic paper is the best.The degradation rates of formaldehyde pollutants of AgBr/BiOBr/PFs,AgI/BiOI/PFs composite photocatalytic paper are 93.3%and 91.5%.After 3 cycles,the XRD patterns of the composite photocatalytic paper before and after cycling are identical,it shows that AgX/BiOX/PFs composite photocatalytic paper is a photocatalytic material with chemical stability and light stability.AgX has a synergistic effect with BiOX,AgX/BiOX/PFs can effectively solve the AgX instability and prevent Ag+ and e-from combining into silver atoms.The above composite materials are characterized by SEM,XRD,XPS,PL and UV-vis means.SEM observation shows that the surface of PFs has densely packed BiOX particles.XRD test shows that the composite photocatalytic paper corresponds exactly to the standard comparison card.The element composition in XPS is the same as that of the composite photocatalytic paper,and the characteristic peaks of the elements can be well fitted.No I and Ag element appeared in the composite photocatalytic paper.PL and UV-vis strongly prove that the light absorption range of composite photocatalytic paper has been widened.The photoelectron-hole pair can be effectively separated.In summary,BiOX composite photocatalytic paper can effectively improve the photocatalytic activity and inhibit the recombination of photo-generated electrons and holes.Thereby,the photocatalytic activity is improved.