【作者】 张扬；

【导师】 彭泽平；

【作者基本信息】 西南大学 ， 凝聚态物理， 2019， 硕士

【摘要】 溶剂热合成法可以在相对较短的时间、温和的液体环境下大量制备结构新颖的纳米材料。近年来,由于在太阳能电池、光催化剂、光伏器件和热电等领域的应用,采用溶剂热合成铜基硫属化合物纳米材料、铯铋卤化钙钛矿纳米材料已展现出快速的发展趋势。众所周知,纳米材料性能的好坏与材料本身的物相、组分、带隙以及尺寸大小保持着高度的一致性。因此,发展新的合成方法构建具有特殊结构的纳米材料对提升材料性能和应用有着重要的意义。本文在国内外大量文献调研的基础上,通过溶剂热合成法快速制备高质量、单分散、形貌尺寸均匀的多元铜基硫属化合物纳米材料、铯铋卤化钙钛矿纳米材料并探究了其生长机理和性质,取得的具体研究成果归纳如下:1.通过溶剂热法以氯化铜、硫脲为前驱源,用二缩三乙二醇和聚乙烯吡咯烷酮分别做溶剂与表面活性剂反应实现了高质量、单分散、形貌尺寸均一、花状的Cu_7.2S₄微纳米材料。X‐射线衍射、电镜和组分分析表明产物为立方相。研究探索了产物的紫外光吸收光谱并提出了相应的生长机理。此外,光催化测试表明获得的Cu_7.2S₄微纳米材料在光催化领域具有潜在的应用前景。2.基于“一步法”实现了高质量、单分散、形貌尺寸均一、立方结构的Cu-Fe-S微纳米材料,进一步丰富了这类窄带半导体的制备方法。X‐射线衍射、电镜和组分分析表明产物为立方相,其粒径分析表明,CuFeS₂微纳米材料的粒径大小⁰.3μm;Cu₅FeS₄微米材料的粒径大小¹.8μm。研究探讨了不同的前驱源和反应温度对产物的影响。此外,光学性质研究表明实验合成的Cu-Fe-S化合物在可见光区具有高吸收系数,并推导出产物的禁带宽度分别为0.56（CuFeS₂）和1.8 eV（Cu₅FeS₄）,较小的带隙值表明吸收峰向长波方向移动,可作为良好的吸光材料应用在太阳能电池、发光二极管、光催化、光伏器件和热电等领域。另外,通过对产物的可见光催化测试表明,实验合成的Cu-Fe-S经多次循环实验后,任能确定其再现性和组成稳定性,说明起催化剂的作用所以可回收利用。3.采用简易的溶剂热法实现了单分散、形貌尺寸均一的四方结构CuFeSe₂微纳米材料。X‐射线衍射、电镜和组分分析表明产物为四方相。其粒径分析表明CuFeSe₂的粒径大小⁰.3μm。探索了酸碱性、反应温度、反应前驱源之比对产物的影响并提出了相应的生长机理,研究表明反应前驱源的比例和温度对产物的纯度有极大的影响。此外,光学性质研究表明实验合成的CuFeSe₂在可见-近红外光区均有吸收,这是由于p型CuFeSe₂微纳米材料中自由空穴的局域表面等离子体共振的结果,较高的吸收系数使其可作为良好的光吸材料应用在光催化等领域。同时,其可见光催化测试也证明了CuFeSe₂微纳米材料是一种优良的催化剂且具有良好的环境适应能力。4.通过溶剂热法以溴化铯、溴化铋为前驱源,用二甲基亚砜和聚乙烯吡咯烷酮分别做溶剂与表面活性剂反应实现了高质量、单分散、形貌尺寸均一的Cs₃Bi₂Br₉纳米材料。X‐射线衍射、电镜和组分分析表明Cs₃Bi₂Br₉纳米结构为三角晶相。同时,考察了活性剂（PVP）、溶剂和温度对形貌的影响。此外,光学性质研究表明实验合成的Cs₃Bi₂Br₉纳米材料在可见光区具有较高吸收系数,表明该纳米晶具有优异的发光性能,可用于薄膜电池、热电材料、光催化等众多领域。此外,我们还采用了溶剂热法制备了较大表面积的Cs₃Bi₂I₉微米材料,电镜分析表明其尺寸高度不均。另外,我们采用Schlenk line技术实现了粒子状Cs₃Bi₂I₉纳米晶体的可控制备。研究发现,采用热注射法制备的纳米晶具有大小均一、尺寸集中的特点。X‐射线衍射、电镜和组分分析表明Cs₃Bi₂I₉纳米结构为六方晶相,同时还发现纳米晶的生长是各向异性的,优先沿c轴生长。此外,光学性质研究表明实验合成的Cs₃Bi₂I₉纳米晶具有优异的光学性能,表明可用于光电转换、薄膜电池、热电材料等领域。更多还原

【Abstract】 Solvothermal synthesis can produce a large number of novel nanomaterials in a relatively short time and a mild liquid environment.In recent years,solvothermal synthesis of ternary copper iron chalcogenide and cesium bismuth halide perovskite nanomaterials has shown a booming development trend due to applications in solar cells,photocatalysts,photovoltaic devices,and thermo-electrics.As we all know,the performance of nanomaterials is closely related to the morphology,structure,composition and size of the materials themselves.Therefore,it is of great significance to develop new synthetic methods to construct nanomaterials with special structures for improving the properties and applications of materials.This paper is based on a large number of literature research at home and abroad,The solvothermal synthesis method is used to control the synthesis of high-quality,monodisperse,uniform shape and size ternary copper iron chalcogenide and cesium bismuth halide perovskite nanomaterials,and explore their growth mechanism and properties,the main parts of the results are summarized as follows:1.Using copper chloride and thiourea as the precursor,triethylene glycol and polyvinylpyrrolidone as the solvent and the surfactant respectively,the Cu_7.2S₄ nanomaterials with high quality,monodisperse,uniform morphology and size and microflower-like structure were prepared by solvent thermal method for the first time.X-ray diffraction,electron microscopy and compositional analysis indicated that the product was a cubic phase.The study explored the UV-visible absorption spectrum of the product,and the corresponding growth mechanism is proposed.In addition,the photocatalytic test showed that Cu_7.2S₄ nanomaterials have been potential applications in the field of photocatalysis.2.Based on the“one-step method”,Cu-Fe-S micro-nano materialwith high quality,monodisperse and uniform size and cubic structure are synthesized,which further enriched the preparation method of such narrow-band semiconductors.X-ray diffraction,electron microscopy and composition analysis showed that the product was cubic phase.The particle size analysis show that the CuFeS₂ micro-nano materialwith size is⁰.3μm;the Cu₅FeS₄ micro-nano materialwith size is¹.8μm.The study investigates the reaction temperature,the influence of the precursor of the reaction on the product and proposed the corresponding growth mechanism.In addition,optical properties study show that the experimentally synthesized Cu-Fe-S have a high absorption coefficient in the visible region,and elicit the forbidden band width of the sample is0.56（CuFeS₂）and 1.8eV（Cu₅FeS₄）,respectively.The smaller band gap values indicate indicates that the absorption peak shifts to the long wave direction,which can be used as a good light absorbing material and has potential application prospects in the fields of solar cells,thermoelectric materials and photocatalysis.In addition,the visible light catalysis test shows that the experimentally synthesized Cu-Fe-S micro-nano materialwith can be determined for reproducibility and composition stability after repeated cycles of experiments,indicating that the catalyst can be recycled.3.The CuFeSe₂ micro-nano materialwith with single dispersion and uniform morphology and size are obtained by simple solvent thermal method.X-ray diffraction,electron microscopy and composition analysis showed that the product was tetragonal phase.The particle size analysis show that the CuFeSe₂ size is⁰.3μm.The effects of acid-base property,reaction temperature and reaction precursor ratio on the product are explored and the corresponding growth mechanism is proposed.The results show that the ratio and temperature of the precursors have great influence on the purity of the product.In addition,optical properties study show that the experimentally synthesized CuFeSe₂ all have absorb in the visible-near-infrared region.This is due to the local surface plasmon resonance of free holes in p-type CuFeSe₂,and it can be used as a good light absorbing material in the field of photocatalysis.At the same time,its visible light catalytic test also prove that CuFeSe₂ micro-nano materialwith are an excellent catalyst and have good environmental adaptability.4.The Cs₃Bi₂Br₉ nanomaterials with high quality,monodisperse and uniform morphology and size are prepared by solvent thermal method with cesium bromide and bismuth bromide as the precursors,respectively using dimethyl sulfoxide and polyvinylpyrrolidone as the solvents and surfactants.X-ray diffraction,electron microscopy and compositional analysis indicate that the Cs₃Bi₂Br₉ nanostructure is a triangular phase.At the same time,the effects of active agent（PVP）,solvent and temperature on the morphology are investigated.In addition,the study of optical property shows that the experimentally synthesized Cs₃Bi₂Br₉ nanomaterials have a higher absorption coefficient in the visible region,indicating that the nanomaterials have excellent luminescent properties and can be used in many fields such as thin film batteries,thermoelectric materials,and photocatalysis.At the same time,we also use this method to synthesize Cs₃Bi₂I₉nanomaterials with large surface area and the electron microscopic analysis shows that the size is highly uneven.In addition,we use Schlenk line technology to realize the controllable preparation of granular Cs₃Bi₂I₉ nanocrystals.This study finds that nanocrystals prepared by hot injection have the characteristics of uniform size and concentrated size.X-ray diffraction,electron microscopy and compositional analysis indicate that the Cs₃Bi₂I₉ nanostructure is a hexagonal phase.Meanwhile,it is also found that the growth of the nanocrystals are anisotropic and preferentially grew along the c-axis.In addition,optical property study shows that the experimentally synthesized Cs₃Bi₂I₉ nanocrystals have excellent optical properties,indicating that they can be used in fields such as photoelectric conversion,thin film batteries,and thermoelectric materials.更多还原