Preparation And Photocatalytic Properties Of MXene Based Nanocomposites

In recent years,photocatalysis has become a hot topic of research as more and more attention is paid to green technologies for solving environmental pollution problems.Currently,photocatalysis is playing an increasingly strong role in pollutant removal.Photocatalysis is the process by which the electrons of a semiconductor photocatalyst are excited to jump from the valence band to the conduction band and form holes and photogenerated electrons in the valence and conduction bands respectively,resulting in strong radical oxidation and redox reactions on the surface of the semiconductor photocatalyst,thus achieving the degradation of organic pollutants.The advantages of photocatalytic reaction are no secondary pollution,good stability,strong catalytic activity and controllable cost.However,a single photocatalytic material has the disadvantages of low utilization of solar light and low quantum effect,so it is of great significance to prepare materials with strong photocatalytic activity and high utilization.Therefore,the photocatalytic degradation efficiency of transition metal oxides such as TiO₂,Zn O,Bi OCl and SnO₂/transition metal carbide Ti₃C₂-MXene is studied.In order to solve this problem,the materials are explored in this paper:（1）The ML-Ti₃C₂-MXene sheet/TiO₂nanocomplex（TiO₂/ML-Ti₃C₂）was obtained by in situ growth of TiO₂nanocrystals between ML-Ti₃C₂-MXene layers using a hydrothermal method.It had a strong ability to remove contaminants under UV irradiation.Then TiO₂/ML-Ti₃C₂composite photocatalyst was prepared using a vapor phase hydrolysis method,which was milder and more conducive to the in situ crystallisation and growth of TiO₂nanospheres,and had a strong ability to remove high concentrations of pollutants under visible light irradiation.It provides a new idea for ML-Ti₃C₂-MXene based composite catalysts in treating wastewater.（2）The research on the expansion of ML-Ti₃C₂-MXene multi-layer material micro space was conducive to the improvement of pollutant adsorption capacity.At present,the main research direction was the preparation of expandable multilayer ML-Ti₃C₂-MXene composites by intercalation of nanoparticles.Due to the high specific surface area and catalytic active center of nano particle photocatalyst,Ti₃C₂-MXene based nanocomposites with high adsorption and photocatalytic properties could be obtained.Zn O,SnO₂and Bi₂Mo O₆were prepared by hydrothermal method,and Zn O/ML-Ti₃C₂,Bi₂Mo O₆/ML-Ti₃C₂and SnO₂/ML-Ti₃C₂nanocomposites were prepared.The results showed that TMO/ML-Ti₃C₂-MXene nanocomposites have folded porous structure and 2D/2D heterostructure.This was because of its folding porous structure,which was conducive to increase the adsorption capacity,and the interface contact area was increased,the 2D/2D heterogeneous structure increases,the charge transfer distance decreases,the separation efficiency of electron hole pair was improved,and the photocatalytic ability was improved.（3）Based on the research status and existing problems of formaldehyde pollution,this chapter studies from the following aspects:The materials with high efficiency,especially the catalytic oxidation function of formaldehyde,were screened out,and the ternary composites of FL-Ti₃C₂/BiClO/SnO₂（FBS）were prepared.Under 15 W UV irradiation,the photocatalytic degradation efficiency of formaldehyde by ternary materials was explored.The results showed that the successful preparation of the ternary materials greatly improved the degradation efficiency of formaldehyde,and had good recycling performance.FL-Ti₃C₂as the catalyst carrier could improve the electron mobility and stability of semiconductor photocatalyst,and enhance the recycling efficiency.And then could develop efficient and stable formaldehyde catalyst,and develop multi-functional MXene based materials for adsorption catalysis.