Controllable Construction And Carrier Regulation Of Two-dimensional BiOCl Based Heterostructures

Photocatalysis,with its advantages of high efficiency,cleanliness and no secondary pollution,has a great development prospects in the direction of dealing with environmental pollution and developing renewable energy,.It is an advanced oxidation technology that can effectively degrade pollutants.Bismuth chloride oxide?BiOCl?,as a typical V-VI-VII group ternary oxide catalyst,has been widely studied for its advantages of non-toxicity,easy preparation,low cost,stable chemical properties and easy regulation of energy band structure.Its unique layered structure of its own[Bi₂O₂]²⁺layers and the alternating arrangement of double-layer Cl atoms is beneficial for the separation of photogenerated carriers.However,its band gap energy is high?³.2eV?,and its utilization efficiency of sunlight still needs to be improved.This thesis is an exploration and research,which aimed at the problem of expanding the visible light response of BiOCl and solving the problem of easy recombination of photogenerated carriers.Based on the energy band design,a series of heterojunction photocatalysts are constructed with semiconductors matching the energy band structure of BiOCl,which can improve the utilization of solar light,and regulate the separation and transfer efficiency of photogenerated carriers at the same time so as to realize the improvement of the photocatalytic performance.The main conclusions are as follows:First,BiOCl nanosheets was synthesized by the solvothermal method,and the0D/2D Ag₂O/BiOCl photocatalytic heterojunction was synthesized in situ by chemically depositing on the substrate of the two-dimensional catalyst.The absorption edge of the sample is red-shifted,the separation efficiency of the photogenerated carriers is improved,and the photocatalytic performance is improved.Second,the 2D/2D ZnIn₂S₄/BiOCl heterojunction was in situ constructed using a simple secondary alcohol thermal method,and the 2D/2D structure can shorten the carrier transport path and increase more active sites.The successful construction of heterojunction broadens the photoresponse range of the catalyst,promotes the separation efficiency of photogenerated electrons and holes,and prolongs the lifetime of photogenerated carriers,thus improving the photocatalytic performance.Third,the Z-type 2D/2D CaIn₂S₄/BiOCl-SOVs heterojunction was prepared by the calcination and hydrothermal method.The effect of surface oxygen vacancy?SOVs?concentration on the photocatalytic activity was explored by controlling the calcination temperature and time.Based on the optimal oxygen vacancy concentration,the effect of CaIn₂S₄ composite on the catalytic performance of BiOCl was discussed.The analysis results of photocatalytic activity enhancement mechanism shows that the synergism between surface oxygen vacancy and CaIn₂S₄ enhances the separation ability of photogenerated e^-and h⁺,increases the lifetime of carriers,and further widens the response of photocatalyst to visible light,thus significantly improving the photocatalytic performance.