Synthesis And Characterization Of Two-Dimensional Tin-Based Sulfide Semiconductor Nanoplates

In recent years,two-dimensional(2D)metal chalcogenide semiconductor nanoplates have attracted great attentions due to their large specific surface area,unique quantum confinement effect and excellent optoelectronic properties,so they are considered as a promising material.Among them,tin-based semiconductor materials,such as Sn S₂,Cu₂Sn S₃,Cu₃Sn S₄ and Cu₂Zn Sn S₄,possess the characteristics of moderate band gap,tunable element ratio,high light absorption coefficient and low cost that make them attractive materials for batteries,catalysis and sensors.However,it is still a challenge to controlled synthesize 2D tin-based semiconductor nanoplates,especially for ternary tin-based compound with non-layered structure.In this thesis,wet-chemistry approach was adopted to controlled synthesize Sn S₂nanoplates of different sizes via two manners:thermal decomposition of a single-source precursor and one-pot method.Moreover,the study on the preparation of 2D ternary Cu-Sn-S semiconductor nanoplates templated by the as-prepared Sn S₂ nanoplates was performed.The main contents are listed as follows:(1)The single-source precursor dibutyltin diisothiocyanate(Bu₂Sn(NCS)₂)was prepared by reaction of dibutyltin dichloride and potassium thiocyanide.2D Sn S₂nanoplates and nanoflowers with 2T phase were successfully prepared by direct thermal decomposition of the Bu₂Sn(NCS)₂in different high-boiling-point organic solvents respectively.It was found that Sn S₂ nanoplates with the size of 400-600 nm were produced by using 1-octadecene(ODE)as the non-coordination solvent and oleic acid(OAc)as the ligand,while the Sn S₂ nanoflowers with the size up to micron level were got by further introducing oleylamine(OAm)as additional ligand.The UV-vis absorption spectra and Mott-Schottky tests on these two Sn S₂ nanomaterials were performed,confirming their band structure,the position of valence band and conduction band.Moreover,the photoelectrochemical cell studies on these nanomaterials also show steady and reproducible photo-response.(2)Phase-pure Sn S₂ nanoplates with a lateral size of 150 nm and a thickness of about 3 nm were successfully prepared via one-pot method by using tin tetrabromide and ammonium thiocyanate.Moreover,the influences of solvent,atmosphere,tin source,Sn/S mole ratio,reaction temperature and time on morphology and crystal structure of the final products were systematically explored.It was found that the byproduct of Sn S was accompanied formed,in addition to the Sn S₂ nanoplates,under the atmosphere of nitrogen.(3)2D ternary Cu-Sn-S nanoplates were successfully synthesized through cation exchange method by using the phase-pure Sn S₂ nanoplates as templates.The influence of Cu⁺/Sn⁴⁺mole ratio,reaction temperature and time on the composition of the ternary nanoplates.It was found that Cu/Sn mole ratio in the ternary nanoplates was highly dependent on the adding amount of the copper source.It should be emphasized that the final morphology of the ternary nanomaterials can be well maintained that of the original Sn S₂ template but with little increasement of the thickness.Therefore,it provides an effective and facile approach to synthesize non-layered 2D nanomaterials by using the cation exchange method.