| Since the discovery of graphene,two-dimensional materials have been an important field of scientific research due to their unique optical,electrical and mechanical properties.As one of the bismuth-based oxygen chalcogenides,Bi2O2Se has attracted a lot of attention recently.For a long time in the past,Bi2O2Se has always been studied as a thermoelectric material.With the continuous advancement of material preparation methods,two-dimensional layered Bi2O2Se has been prepared,exhibiting many unique electrical,optical and physical properties.The few layers of Bi2O2Se have extremely high mobility,excellent stability,adjustable band gap and excellent mechanical properties,and show extraordinary performance in the fields of electronics and optoelectronics.Therefore,this paper uses bismuth nitrate pentahydrate as the bismuth source,selenium powder as the selenium source,and hydrazine hydrate as the reducing agent,and adopts a simple and easy-to-operate molten salt method to prepare Bi2O2Se nanosheets.At the same time,we constructed Bi2O2Se-Ti O2 heterojunction by adding Ti O2 in the preparation process of Bi2O2Se.When synthesizing Mo S2,the synthesized Bi2O2Se was added to form a Bi2O2Se-Mo S2 heterojunction.On this basis,photoelectrochemical self-powered detectors based on Bi2O2Se,Bi2O2Se-Ti O2 heterojunction and Bi2O2Se-Mo S2 heterojunction were constructed,and their photoelectric properties were explored.In the process of using the molten salt method to synthesize Bi2O2Se nanosheets,we separately explored the influence of time,temperature,Na OH concentration,and the ratio of molten salt on the reaction products.The effect of the ratio on the reaction product.It was found that the reaction time was too short and the reaction temperature was too low,and the reaction precursors could not be converted into Bi2O2Se nanosheets.With the increase of time and temperature,the reaction began to proceed gradually,and the size of the nanosheets gradually increased.As an additive in the reaction process,Na OH has the function of promoting the conversion of reaction raw materials and controlling the growth direction of the product.By adjusting its concentration,it is found that when the concentration is too low,the reaction product cannot be completely converted,and the obtained product has many pores.When the concentration is too high,the morphology of the reaction product changes seriously and no longer exhibits a flaky structure.KNO3 and Li NO3 mixed salts are used for experiments.The molten high-temperature ionic liquid can prevent agglomeration on the one hand,and on the other hand can promote the lateral growth of nanosheets through ion adsorption.By changing the ratio of the two salts,it can be found that KNO3 can control the morphology of the nanosheets,while Li NO3 can make the surface smoother.Using optimized Bi2O2Se synthesis conditions,Bi2O2Se-Mo S2heterojunction and Bi2O2Se-Ti O2 heterojunction were constructed respectively.Construct photoelectrochemical self-powered detectors,use the materials prepared above as photoanodes,and explore their photoelectric properties.The test results show that when sulfur electrolyte is used as the medium,the light response of the detector is the highest.Under the same optical power,using different wavelengths of light for testing,the detectors all show a higher optical response,which represents an ultra-wideband detection.For the composite heterojunction material,its photocurrent,response time,responsivity and detection rate are all improved compared to the pure material. |
