TiO₂ Nanoparticles Anchoring On Two-dimensional Bi₂Se₃ Nanosheet As An Enhanced Visible Light Catalyst

Photocatalytic technology is one of the important means to solve the energy shortage and the deterioration of the ecological environment in today’s society.Since the discovery of the semiconductor photocatalytic effect in 1972,semiconductor photocatalytic materials have received extensive attention due to their good application prospects.Among them,Ti O₂has become an ideal environment-friendly material due to its stable chemical properties,strong oxidizing ability and high-efficiency photocatalytic activity.However,Ti O₂has a large band gap,narrow absorption spectrum,unstable photo-generated carriers,and extremely easy recombination,which severely restrict its large-scale development and application.Therefore,in order to improve the photocatalytic performance of Ti O₂,it can be improved by means of adjustment,doping,deposition and semiconductor heterojunction.Since graphene was successfully prepared,two-dimensional materials have developed rapidly,and high-performance,multi-functional composite materials developed based on two-dimensional materials have been widely reported.As a typical topological insulator material,two-dimensional Bi₂Se₃nanosheets have been widely used in electronics,energy,catalysis and other fields due to their remarkable thermoelectric properties,high conductivity,photosensitivity and electrochemical properties.Based on this,this paper constructs a heterojunction of Ti O₂and two-dimensional Bi₂Se₃nanosheets to solve the problems of fewer reaction sites and easy recombination of photo-generated carriers.At the same time,the graphene-aerogel network structure is constructed to improve the photoelectric conversion efficiency.The main research content is as follows:1.Two-dimensional Bi₂Se₃nanosheets were obtained by liquid phase exfoliation,and Ti O₂/Bi₂Se₃hybrid nanosheet composites were prepared by a simple ultrasonic route.Through X-ray diffraction and Raman characterization,it is determined that the prepared sample is pure and well-crystallized.In addition,the photoelectrochemical measurement results show that Ti O₂/Bi₂Se₃HNs exhibits a current density of about 4.3μA cm^-2without an external bias voltage,which is much better than pure Ti O₂and Bi₂Se₃.More importantly,the photocurrent density decreased by only 10%after 125 cycles,showing good cycle stability.The improvement of photocatalytic activity is attributed to the unique characteristics of two-dimensional Bi₂Se₃nanosheets,maximized reaction sites and good conductivity,as well as the positive coupling effect of Ti O₂/Bi₂Se₃heterojunction.This study shows that Ti O₂/Bi₂Se₃HNs photocatalyst has excellent potential for photocatalytic applications.2.Successfully prepared ternary mixed size Ti O₂/Bi₂Se₃/graphene-aerogel through self-assembly.Ti O₂nanoparticles were loaded on two-dimensional Bi₂Se₃nanosheets,and Ti O₂/Bi₂Se₃hybrids were embedded in three-dimensional（3D）graphene-Aerogel.The photoresponse performance of the composite material under different light intensity and different external voltage was studied systematically.It was found that the photocurrent density of the structure was always higher than that of pure Ti O₂and Ti O₂/Bi₂Se₃HNs under the same environmental conditions.The structure can not only make full use of the coupling effect between the three materials,but also the multi-dimensional mixed-size structure can make full use of the advantages of materials of various sizes to maximize the photocatalytic performance of the material.At the same time,the study also found that it can still maintain good light responsivity after continuous working for more than 1500 s.The research content provides a new idea for expanding solutions to Ti O₂defects.