【作者】 赵凯；

【导师】 张淑芬；

【作者基本信息】 大连理工大学 ， 化学工程与技术， 2018， 硕士

【摘要】 近年来,单分散性纳米材料由于形貌和尺寸均一、且在特定介质中具有良好的分散性而受到科研工作者的广泛关注。通常,在它的合成过程中需要加入不同种类的长碳链配体以控制粒子的组成、尺寸和形貌。然而,表面配体的存在会对粒子的催化性质、导电性质和生物相容性等产生不利的影响。基于此,本文合成了一系列不同种类的纳米材料,并以表面络合十八胺的Pd纳米颗粒为例,选用亲电试剂苯甲酰氯对其表面的配体进行反应性剥离,并以此反应探究了反应性配体剥离的机理。而后,分别考察了亲电试剂和纳米材料的种类对配体剥离结果的影响。另外,分别将配体剥离前后的Pd纳米颗粒和一系列功能性纳米材料应用于催化、降解和生物成像等领域,并系统地考察了各自的性能。首先,通过热分解法合成了表面络合长碳链十八胺的Pd纳米颗粒和不同配体络合的一系列功能性纳米材料,包括:Au和Ag₂S纳米球、上转换NaYF₄:Yb/Er、TiO₂纳米棒、MoS₂纳米片、Fe₃O₄、Cu₂ZnSnS₄（CZTS）、Ni₂P和CoO等纳米颗粒。从透射电镜和X射线衍分析得到各个粒子的形貌尺寸和结构,从红外谱图中证实每种粒子的表面均络合有长碳链配体。其次,以苯甲酰氯与Pd之间的反应为例,通过红外、核磁和能谱等相关表征结果证明了在改性过程中长碳链配体被剥离的事实,并以此反应证明了配体剥离过程是基于亲电取代反应机理。而后,分别选取三聚氯氰、三氯化磷和2-溴异丁酰溴对Pd进行配体剥离,证明了亲电试剂的种类对配体剥离的结果没有影响。此外,用苯甲酰氯对不同配体络合的功能性纳米材料进行配体剥离,说明了纳米材料的种类对配体剥离的结果没有影响。最后,将配体剥离前后的Pd分别应用于催化还原对硝基苯酚（4-NP）和催化Na BH₄产氢,结果发现配体剥离之后的Pd催化还原4-NP的反应速率常数是0.36 min^-1,显著大于配体剥离之前Pd的0.03 min^-1,并且高于文献上报道的TiO₂负载1 mol%的Pd的0.19 min^-1,另外从Au催化还原4-NP中可以得到类似结论。另外,配体剥离之后的CoO和Ag₂S分别能够应用于催化NaBH₄还原亚甲基蓝（MB）和作为光催化剂降解甲基橙（MO）,且催化活性良好。由于配体剥离之后NaYF₄:Yb/Er能够稳定的分散在水中,同时展现出优良的上转换发光性质,因此将其应用于活体生物成像,结果证明配体剥离后的NaYF₄:Yb/Er在生物成像领域展现出巨大的应用潜力。更多还原

【Abstract】 In recent years,monodispersed and stable nanomaterials have attracted great attention due to uniformity in size and shape,and having favorable dispersion ability in certain media.Usually,different types of long hydrocarbon ligands are involved in the process of synthesis to control the composition,size and morphology of nanocrystals（NCs）.However,the presence of surface ligands will have an adverse effect in catalysis,electric conduction and biocompatibility.Hence,in this paper,a series of nanomaterials were synthesized firstly,and benzoyl chloride was used as an electrophile for reactive removal of octadecylamine（ODA）from Pd NCs surface,and the mechanism of reactive ligand stripping was investigated according to this reaction.Next,the effects of types of electrophiles and nanomaterials on the results of ligand stripping were investigated,respectively.In addition,Pd NCs and a series of functional nanomaterials before and after ligand stripping were applied in catalysis,degradation and biological imaging,and their performances were systematically inpected.First of all,Pd NCs capped with ODA and a series of functional nanomaterials capped with different kinds of long hydrocarbon ligands were synthesized through thermal decomposition method.Meanwhile,the above functional nanomaterials included Au and Ag₂S nanospheres,upconverting NaYF₄:Yb/Er,TiO₂ nanorods,MoS₂ nanosheets,Fe₃O₄ NCs,Cu₂ZnSnS₄（CZTS）NCs,Ni₂P NCs and CoO NCs.The morphology and structure of each NCs were obtained from transmission electron microscopy and X-ray analysis.Moreover,it was proved from the infrared spectra that the surface of each NCs is capped with long hydrocarbon ligands.Next,taking the reaction between benzoyl chloride and Pd as an example,it was proved that the long hydrocarbon ligands were stripped in the modification process through performing FT-IR,¹H-NMR and EDS characterizations for Pd NCs before and after ligand stripping,and the mechanism of reactive ligand stripping was demonstrated according to this reaction.Moreover,cyanuric chloride,phosphorus chloride and 2-bromoisobutyryl bromide were chosen to strip the ODA from Pd NCs.It was proved that the types of electrophiles have no effects on the results of ligand stripping.In addition,benzoyl chloride was used for reactive removal of surface ligands from a series of functional nanomaterials,and similarly it was proved that the types of nanomaterials have no effects on the results of ligand stripping.Finally,Pd NCs before and after ligand stripping were applied to catalytic reduction of4-NP and catalytic hydrogen generation of NaBH₄,respectively.It was found that the reaction rate constant of the catalytic reduction of 4-NP by the ligand-stripped Pd was 0.36 min^-1,significantly greater than that of 0.03 min^-11 by Pd NCs before ligand-stripping process and of0.19 min^-1 by TiO₂/1 mol%Pd microspheres according to the literature.Moreover,a similar conclusion can be obtained from catalytic reduction of 4-NP by Au NCs.Furthermore,the ligand-stripped CoO and Ag₂S NCs can be applied to catalytic reduction of MB and degradation of MO as photocatalyst,and the catalytic activity is favorable.Due to the stable dispersion of the ligand-stripped Na YF₄:Yb/Er in the water,meanwhile showing the excellent upconversion luminescence（UCL）property.Therefore,it can be applied to biological imaging.The results show that the ligand-stripped NaYF₄:Yb/Er has great potential in the fields of bioimaging.更多还原