Solvothermal Preparation Of Metastable CaTi₂O₅-Based Micro-Nano Structures And Its Photocatalytic Properties

Photocatalytic degradation is an emerging wastewater treatment technology with promising industrial applications.Nano/micro materials with controllable size and morphology have a broad application in the field of photocatalysis due to their unique micro-nano structure,dimensional size and high specific surface area.In view of the difficulty of controllable synthesis of micro-nano structure and the easy agglomeration of traditional nano-powder photocatalysts,this topic proposes metastable CaTi₂O₅ as a new type of photocatalyst,and uses a simple solvothermal method to control the mesoporous micro-nano structure of metastable CaTi₂O₅.And its photocatalytic performance was studied.In this paper,the preparation process of metastable CaTi₂O₅was optimized first.In order to further broaden its practical application,it was compounded with biomass source chicken feathers and Ag,respectively,using X-ray diffraction（XRD）,field emission scanning electron microscopy（FESEM）and transmission electron microscopy.（TEM）,high-resolution transmission electron microscopy（HRTEM）,ultraviolet diffuse reflectance（UV-VIS）,FT-IR,BET and other testing methods were used to characterize and analyze the structure,morphology and photocatalytic properties of the samples.The experimental results are as follows:In the absence of templates or surfactants,micro-nano CaTi₂O₅structures with higher photocatalytic activity than P25 photocatalysts were prepared by optimally changing the solvothermal time.When the solvothermal time was 36 h,the obtained fusiform CaTi₂O₅structure exhibited the highest photocatalytic activity.Under ultraviolet（UV）light irradiation,the photocatalytic degradation rate of its fusiform structure to degrade methyl orange（MO）reaches 99.33%within 25 min,which is mainly due to its metastable structural characteristics,high crystallinity and large due to the specific surface area.The growth mechanism of CaTi₂O₅fusiform structure is mainly controlled by crystallization-oriented attachment-Oswald maturation growth.Taking advantage of the characteristics of low-cost biomass source chicken feathers rich in N and P,and by changing the amount of chicken feathers added and the solvothermal time,a spherical micro-nano structure of N and P co-doped CaTi₂O₅with high photocatalytic activity was prepared.When the solvothermal time was 24 h and the solvothermal temperature was 180°C,the as-prepared mulberry-like spherical micro-nanostructure samples assembled from spherical nanounits achieved a 100%degradation rate of MO under UV light for 20 min.This was mainly due to the fact that N,P co-doping led to its large specific surface area,high crystallinity and lattice distortion,the growth mechanism of N,P co-doped CaTi₂O₅mulberry spherical micro-nano structure is mainly controlled by the growth and aggregation of crystal nucleus-self-assembly.In order to further broaden its visible light application range,Ag/AgCl/CaTi₂O₅photocatalysts were prepared by one-step solvothermal method.Under visible light,the as-prepared samples exhibited good photocatalytic performance within 180 min,following a pseudo-first-order reaction kinetic model.The enhanced mechanism of visible light photocatalytic activity is also described.Under visible light,when AgNO₃ was added at 6%,the prepared CaTi₂O₅composite sample achieved 96.3%MO degradation rate at 180 min,which was mainly due to the reduction of the forbidden band width of the sample due to the composite of Ag,and the red shift of the absorption edge.,improve the visible light response of the sample,the sample has a good specific surface area and crystallinity,which improves the photocatalytic activity of the sample,and the smaller impedance and PL energy promote the separation of photogenerated electrons and holes,which is conducive to the separation of photogenerated carriers.generated,further promoting the response of the sample to visible light.After 5 cycles,the sample still has good photocatalytic activity.