Preparation And Photocatalytic Properties Of Bismuth Compounds And Its Composites

In recent years,photocatalysis technology has been vigorously developed,and various kinds of photocatalysis are constantly emerging.In practical application,the conventional photocatalysis（Ti O₂,ZnO and Sn O₂）are limited due to their broad band gap and the only absorptive action to UV light（4%sunlight）.A large number of studies have shown that bismuth-based compounds and their composites have the higher photocatalytic activity under visible light,unique structures and excellent performance.Based on the above reasons,three bismuth compounds and their composites were prepared by template method,hydrothermal method,in-situ ion exchange method and photo-reduction method in this thesis.The structural characteristics and photocatalytic performances of the prepared materials were investigated.The main contents of the researches are as follows:（1）Using ordered porous ZnO as precursor,Na₃SSA as structure-directing agent,and bismuth nitrate as bismuth source,a novel camellia-like ordered mesoporous Bi₁₂ZnO₂₀compound was synthesized by hydrothermal method.The ordered mesoporous with 3.5nm diameter were regularly distributed on the surfaces of the petals of camellia-like Bi₁₂ZnO₂₀compound,which led to the specific surface area of the material reach to 98.37 m²·g^-1.The camellia-like Bi₁₂ZnO₂₀ photocatalytic material showed the much excellent photodegradation and photocatalytic hydrogen production performances under visible light irradiation.The Rh B degradation rate was 98.5%in 70 min,and the hydrogen production amount was 18.701 mmol·g^-1 in 3 h.It could be attributed to which the 2D layered structures and ordered mesoporous structure provided the larger specific area,the more active sites and the more efficient electronic transmission efficiency.（2）Under the hydrothermal environment,a kind of uniform 3D spherical flower-like Bi₂O₂CO₃ matrix material was successfully synthesized by template method,and then it was valcanized in situ in the different amounts of thioacetamide（TAA）at room temperature,amorphous Bi₂S₃ was deposited on the surface of Bi₂O₂CO₃ as photosensitizer,and the Bi₂S₃/Bi₂O₂CO₃ composite material was successfully prepared.The influence of different dosage of vulcanizator on the structure,properties and visible light response of Bi₂S₃/Bi₂O₂CO₃ were investigated.The results showed that the amorphous Bi₂S₃ not only greatly broadened the optical response range of the material,but also improved the catalytic activity of the material under visible light.The Rh B degradation rate by the 3D spherical flower-like Bi₂S₃/Bi₂O₂CO₃ composite material reached to 99.7%in 60 mins,and it has the beter photosensitivity and photocatalytic stability.（3）Using 3D spherical flower-like Bi₂O₂CO₃ as the precursor,the spherical flower-likeβ-Bi₂O₃ materix was further obtained by thermal decomposition method on the basis of maintaining the original morphology,the spherical-like AgBr was embedded between the petals of the flower-like structure,and the embedded composite was obtained.And then the Agquantum dots were modified on the surface of the AgBr nanospheres by photoreduction method to build the Z-scheme heterojunction AgQDs-AgBr/β-Bi₂O₃composite.The prepared spherical flower-like Z-scheme AgQDs-AgBr/β-Bi₂O₃ composite photocatalyst had the larger specific surface area and the stronger absorbability to visible light.The catalyst showed the excellent photocatalytic degradation performances under visible light radiation.The Rh B degradation rate reached to 99.85%in 30 min which was about 1.42 times of pureβ-Bi₂O₃ matrix.