Solution-Phase Synthesis,Surface Modification And Photoelectronic Properties Of Sb/Bi Metal Sulfide Nanorods

As an important semi-conductor material,sulphide exhibits important value of application in energy,catalysis,optoelectronics and other fields.With the development of nanoscience and technology,a series of new research advances have been made in one-dimensional sulfide nanomaterials.However,many opportunities and challenges still remain in many aspects such as material synthesis,compositional morphology control,surface modification of materials,and the correlation between these factors and the electronic and optoelectronic properties of materials.This dissertation focuses on the synthesis one-dimensional nanorods,component modulation,surface modification and optoelectronics performance,and the application of photodetectors of Sb₂S₃,(Bi_xSb_1-x)₂S₃,AgBiS₂.The main research contents and results are as follows:In the first part of this dissertation,we prepared ternary(Bi_xSb_1-x)₂S₃（0<x<1）nanorods with a adjustable ratio of length to diameter and Bi/Sb respectively,which are synthesized by simple colloidal route.The aspect ratio of the ternary nanorods increases as the Sb content in the precursor increases.In this experiment,ITO/(Bi_xSb_1-x)₂S₃/ITO optoelectronic devices were fabricated using(Bi_xSb_1-x)₂S₃ nanorods with different ratios of Bi/Sb as active materials,and the photoelectric properties were evaluated.Compared with the unmodified nanorods,the photoconductivity and photoresponsivity of the thiol-modified nanorods are significantly enhanced;Increasing the proportion of Sb component,thiol modification failed to effectively improve the photoconductivity of(Bi_xSb_1-x)₂S₃ nanorods.At the same time,combined with photoelectron spectroscopy（XPS）surface chemical analysis,it was found that the surface oxidation of(Bi_xSb_1-x)₂S₃ nanorods is not beneficial to electron transport,thereby reducing the photoconductivity of the material.On the other hand,combining literature and the atomic model,we propose that the surface modification of thiol can effectively reduce the S-vacancy defect on the(Bi_xSb_1-x)₂S₃ surface,thereby enhancing the photoelectric properties of the material.However,for(Bi_xSb_1-x)₂S₃ nanorods with a high proportion of Sb,due to the introduction of more S vacancies due to the increase of Sb,thiols can not completely eli minate the vacancies and thiol modification brings about oxidation of the nanorod surface,instead leads to the nanorods’photoconductors sexual deterioration.In the second part of this paper,the growth of Sb₂S₃ crystal c-axis was promoted by doping with Bi³⁺,and Sb₂S₃ nanorods with uniform morphology were obtained.Combined with TEM and EDS analysis,the distribution of Bi and Sb in different positions of Bi³⁺-doped Sb₂S₃nanorods is different.Bi elements are mainly distributed in the middle of nanorods;this experiment uses CuSCN in DMF solution the surface modification of Sb₂S₃ nanorods at room temperature.The nanorods were surfaces modified and assembled as ITO/Sb₂S₃/ITO optical devices for optoelectronic performance testing.The test found that CuSCN enhances the optoelectronic devices of Sb₂S₃ nanorods.It responds to IR（985 nm）,UV（365 nm）,sunlight,white light,and monochromatic light,and has high sensitivity and good stability.Based on the analysis,we believe that on the one hand CuSCN/DMF solution can replace longchain a mines encapsulated on the surface of nanorods and improve the electron transfer efficiency between nanorods;on the other hand,CuSCN and Sb₂S₃ form p-n junctions.These two factors promote the photoelectric response of Sb₂S₃ nanorods simultaneously.In the third part of this paper,the ternary AgBiS₂ nanorods were successfully prepared using Bi₂S₃ nanorods as templates using ion exchange reaction.This is the first report of the using of the template method,Ag-DDT composite as an additive,to obtain pure-phase one-dimensional AgBiS₂ nanorods.It was found that the Ag-DDT complex as an Ag source can effectively control the reaction rate of Ag⁺and Bi₂S₃ nanorods and inhibit the growth of Ag₂S impurities.The amount of the substance plays an important role in the complete conversion of template Bi₂S₃:with Ag⁺The amount of DDT increased（0 mmol⁰.5 mmol）,and the peak intensity of Bi₂S₃ in the XRD pattern sequentially decreased until the peak dis-appeared,while the peak position of AgBiS₂ increased in turn;When the Ag:Bi element ratio is larger than 1:1,an impurity peak of Ag appears in the spectrum.We also explored the effects of reaction temperature and reaction time of template Bi₂S₃ and Ag-DDT on the synthesis of ternary sulfide:When Ag:Bi ratio is 1:1,Bi₂S₃ can be complete converted to AgBiS₂ at 140°C;When the Ag:Bi element ratio is 1:1,a reaction is required at 160°C for 10 min,and Bi₂S₃ can be completely converted.At the same time,we preli minary studied the photoelectric properties of the ternary sulfide AgBiS₂.The ITO/AgBiS₂/ITO optoelectronic device fabricated using the ternary sulfide AgBiS₂ has strong I-V photoresponse under all-optical,450 nm,550 nm,and 650 nm light irradiation,and the I-T curves at various wavelengths shows excellent repeatability and stability.At the same time,we also found that the synthesis of ternary sulfides at different temperatures,the assembled optoelectronic devices have good performance in light response.