Study On Ti₃C₂ Based Two-dimensional MXene Material And Its Photoelectrocatalytic Properties

In recent years,with the continuous research on two-dimensional materials,it is found that this material has brought about considerable breakthroughs in many fields.Such a discovery makes two-dimensional materials have important research value.In the development of 2D materials,two-dimensional(2D)transition metal carbides/nitrides(MXenes)have received extensive attention from researchers due to their unique structural properties.As the earliest prepared member of MXene materials,Ti₃C₂ not only has the characteristics of high stability and flexible regulation,but also has abundant active sites,so it has a very broad prospect in application.Especially in the field of catalysis,MXenes show excellent potential for application.After thinking about the development and utilization of abundant solar energy resources and water resources in Tibet,the main research content of this paper is the preparation of two-dimensional Ti₃C₂T_x materials and their photoelectric catalytic performance.Influenced by,Ti₃C₂T_x composites were further prepared,and their photo/electrocatalytic properties were studied.The specific research results are as follows:(1)The effect of different etching conditions on the structure of Ti₃C₂T_x:In this paper,Ti₃C₂T_x was prepared by alkali(NaOH)-assisted hydrothermal method.Since the preparation material does not contain HF,the preparation conditions of this method are relatively warm,and the process is also more environmentally friendly.The effects of temperature,NaOH concentration and etching time on the etching effect were investigated experimentally.Through characterization and testing,the results show that the best etching effect is obtained when the temperature is 280?,the NaOH concentration is 29.5 M,and the etching time is 18 h.Ti₃C₂ two-dimensional nanosheets with hexagonal structure were successfully prepared with the lattice constants:a=b=3.05(?),c=23.86(?).In addition,after testing the samples,it was found that with the increase of etching time,the crystallization effect of the samples was better,but the nanosheets on the surface of the samples were prone to fragmentation.(2)Ti₃C₂/TiO₂ heterojunctions were prepared in-situ by high temperature calcination of two-dimensional Ti₃C₂ materials.Because of its poor solubility in aqueous solution,Ag₃PO₄ was used as the loading material.82.1%degradation rate for Rhodamine B was achieved in the first three minutes of Ti₃C₂/TiO₂/Ag₃PO₄ heterojunction,which was accelerated by 21.8%compared with Ag₃PO₄,indicating that Ti₃C₂/TiO₂ in-situ heterojunction can promote the separation and diffusion of photogenerated carriers and improve the photocatalytic performance.The degradation of Rhodamine B by Ti₃C₂/TiO₂/Ag₃PO₄ stabilized in the first 10 min and reached 97.6%,while the degradation of Rhodamine B by Ti₃C₂+TiO₂+Ag₃PO₄ composite material was only 73.2%in the first 10min.From another aspect,it also indicates that the in situ growth of Ti₃C₂/TiO₂ heterojunction produces a synergistic effect and improves the photocatalytic efficiency.(3)Ti₃C_2/NiFeMn-LDH composite electrocatalytic materials were prepared.The test results showed that the overpotential of Ti₃C₂/NiFeMn-LDH reached 408 mV with a Tafel slope of 70 mV dec^-1,which was 3.7%and 21.4%higher than those of NiFeMn-LDH,respectively,comparable to the commercial catalytic electrode RuO₂.This was attributed to the high conductivity of layered Ti₃C₂,which reduced the reaction resistance of the electrocatalyst,compared to NiFeMn-LDH by 46.3%,which significantly improved the electrocatalytic activity of the composite electrocatalytic material.Two-dimensional Ti₃C₂ materials and their composites have the advantages of enhanced photocatalytic and electrocatalytic performance.By optimizing the preparation conditions of two-dimensional Ti₃C₂materials,the photocatalytic efficiency was improved and the defects of the composites in photoelectrocatalytic performance were improved,providing a solid foundation for the application of two-dimensional Ti₃C₂materials.By compounding with other materials,a series of composites with photo/electrocatalytic activity were prepared,providing a theoretical basis for the expansion of photo/electrocatalytic materials.With the abundant light energy resources and water resources in Tibet,the 2D Ti₃C₂materials show important application prospects in the field of new energy development and environmental protection in Tibet.