Room Temperature Preparation Of Layered I(Pt)/Bi 2 O 2 CO 3 Photocatalyst And Its Photocatalytic Properties

Bi₂O₂CO₃ is a novel Bi-based photocatalyst with a layered structure,which has many advantages such as green non-toxic,easily availiable material and controllable morphology.It has been paid more and more attention in the field of photocatalysis for its good pollutant degradation activity under ultraviolet light irradiation.At present,most of preparation methods of Bi₂O₂CO₃ are concentrated on hydrothermal and solvothermal methods at high temperatures,which is due that the hierarchical Bi₂O₂CO₃ is generally easy to be obtained by theses hydrothermal and solvothermal methods.With respect to high temperature synthesis,the room temperature preparation method possesses obvious advatages,e.g.low-cost,greenness and pollution-free.Therefore,the controllable preparation of hierarchical Bi₂O₂CO₃at room temperature is of great significance.In this diseertation,a room temperature preparation method using BiOHC₂O₄ as a template was first explored and Bi₂O₂CO₃ based composite with a hierarchical structure were obtained,and then the effects of I and Pt on the structure and photocatalytic performance of Bi₂O₂CO₃ were further studied.The main research contents are as followings:Firstly,BiOHC₂O₄/Bi₂O₂CO₃ microrods and Bi₂O₂CO₃ nanosheets with hierarchical structure were in-situ prepared at room temperature by adjusting the ratio of raw materials using BiOHC₂O₄ as a template.The obtained product has low density,large specific surface area and good dispersion properties.Compared to the Bi₂O₂CO₃ prepared by the precipitation method,all Bi₂O₂CO₃-based samples prepared by this template method exhibited more excellent photocatalytic activity.And the BiOHC₂O₄/Bi₂O₂CO₃ microrods exhibited photocatalytic performance superior to that of pure Bi₂O₂CO₃ nanosheets due to their good photo-generated carrier transfer,mass transfer capacity and energy band matching.Secondly,BiOHC₂O₄ was used as a template,I-doped Bi₂O₂CO₃ based composites with different compositions and structures were synthesized by adjusting the molar ratio of I^-to CO₃^2-.The results showed that I^-is doped to the lattice of Bi₂O₂CO₃ in the form of substituted partial CO₃^2-by I^-,which has a significant effect on the microscopic morphology and bandgap energy of Bi₂O₂CO₃.At the same time,the photo-generated carrier separation efficiency of Bi₂O₂CO₃ was greatly enhanced by I-doping.Therefore,the significantly enhanced photocatalytic activity was obtained over the I-Bi₂O₂CO₃.In particular,under of simulated sunlight,nearly 20 times photocatalytic activity of the optimized sample I_0.875-Bi₂O₂CO₃ was obtained with respect to Bi₂O₂CO₃ for the degradation of phenol after 60 min light irradiation.Thirdly,Pt^?II/IV?Cl_x and Pt?0?-supported BiOHC₂O₄/Bi₂O₂CO₃ composites were prepared by photoreduction and NaBH₄ reduction using BiOHC₂O₄/Bi₂O₂CO₃ as the carrier.Both Pt^?II/IV?Cl_x and Pt?0?-supported BiOHC₂O₄/Bi₂O₂CO₃ composites exhibit good visible light absorption capacity.Compared to Pt?0?loaded complexes,due to its larger specific surface area,faster carrier migration ability and appropriate visible light response capability,Pt^?II/IV?Cl_x loaded complexes exhibited significantly enhanced photocatalytic degradation activity of MO under the UV and visible light,while the Pt?0?loaded complexes exhibited suppressing photocatalytic degradation activity of MO under UV illumination.