Preparation And Properties Of Bismuth-based Compound Nanomaterials

At present,the rapid consumption of energy in the world has posed significant challenges to the global scientific community.The semiconductor photocatalysis technology is considered as a kind of sustainable development technology.Bismuth-based photocatalysts have a special layered structure and excellent stability,which has a good applicable prospect in the field of photocatalysis.However,due to the shortcomings of bismuth-based photocatalysts,such as wide bandgap and easy recombination of photo-generated carriers,their practical application is limited.Therefore,it is a valuable research topic to modify bismuth-based photocatalysts to improve their photocatalytic activity.In this dissertation,four bismuth-based heterojunction photocatalysts are prepared by a combination of electrospinning,solvothermal method and high-temperature solid-phase method,and their structures,morphologies,photocatalytic properties and photocatalytic mechanisms are thoroughly studied.The specific contents are as follows:（1）A self-supporting Z-scheme heterostructured PVDF/Bi₂O₂CO₃/g-C₃N₄ composite nanofiber piezoelectric photocatalytic film was prepared by a combination of electrospinning,solvothermal and high-temperature solid-phase method,which has good photocatalytic activity.The photocatalytic degradation rates of methylene blue（MB）,rhodamine B（Rh B）,methyl orange（MO）and tetracycline hydrochloride（TCH）are respectively 91.2%（60 min）,78.9%（60 min）,56.2%（60 min）and 55.7%（60 min）under the synergistic effect of simulated sunlight irradiation and mechanical force.（2）Bi-Bi₂O₂CO₃/N-doped C composite nanofibers were constructed by combining an electrospinning technology and a solvothermal method.The composite sample shows good photocatalytic activity and electrochemical performance,and the photocatalytic degradation rate of tetracycline hydrochloride reaches 82.1%（60 min）under simulated sunlight illumination.In the three-electrode system,when the current density is 1 A g^-1,the specific capacitance is 362 F g^-1.Besides,the initial capacitance retention rate is about 60.2%after1000 charges and discharges at 5 A g^-1,so the catalyst has superior bi-functional characteristics.（3）Black Ti O₂/Bi₂O₂CO₃/Graphene composite aerogel photocatalysts were constructed by combining electrospinning technology,solvothermal method and high temperature solid-phase method.A Z-scheme heterostructure is formed between black Ti O₂ and Bi₂O₂CO₃,which improves the photocatalytic activity of the composite sample.Under simulated sunlight irradiation,the photocatalytic degradation rates of rhodamine B and Congo red（CR）are as high as 93.5%（40 min）and 89.6%（70 min）,respectively.Moreover,the photocatalyst maintains good photocatalytic activity after three cycles.（4）Bi₂Al₄O₉/g-C₃N₄ composite photocatalysts were prepared by electrospinning technology and high-temperature solid-phase method.Bi₂Al₄O₉ and g-C₃N₄ are in close contact to form a uniform and stable type II heterojunction.Under simulated sunlight irradiation,the composite sample shows excellent photocatalytic activity,and the photocatalytic degradation rates of rhodamine B and tetracycline hydrochloride reach 89.6%（50 min）and 84.5%（40 min）,respectively.The composite photocatalyst reduces the recombination rate of photo-generated carriers,enhances the light absorption capacity,and so improves its photocatalytic activity.