物理化学学报 >> 2020, Vol. 36 >> Issue (9): 1908041.doi: 10.3866/PKU.WHXB201908041

所属专题: 精准纳米合成

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金二元纳米晶超晶格的自组装和结构表征

赵亚楠, 何敏, 刘晓芳, 刘斌, 杨建辉()   

  • 收稿日期:2019-08-30 录用日期:2019-09-24 发布日期:2019-09-27
  • 通讯作者: 杨建辉 E-mail:jianhui@nwu.edu.cn
  • 基金资助:
    国家自然科学基金(21501141);唐仲英基金会和陕西省高等教育“一流学科”建设计划资助项目

Self-Assembly and Structural Characterization of Au Binary Nanocrystal Superlattices

Yanan Zhao, Min He, Xiaofang Liu, Bin Liu, Jianhui Yang()   

  • Received:2019-08-30 Accepted:2019-09-24 Published:2019-09-27
  • Contact: Jianhui Yang E-mail:jianhui@nwu.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(21501141);the Cyrus Tang Foundation for Tang Scholar and the "Top-rated Discipline" construction scheme of Shaanxi higher education

摘要:

将双组分纳米晶(例如金属、磁体和半导体)混合物组装成二元纳米晶超晶格为构建新型材料提供了一条新的途径。二元纳米晶超晶格不仅具有有趣的结构,还表现出了其构建单元的复合以及集体的性能,因此被广泛应用于电磁器件领域。然而大多数的研究主要集中在不同尺寸的双组分纳米晶自组装成的二元纳米晶超晶格。很少有报道研究不同尺寸单组分纳米晶,尤其是金纳米晶构筑的二元纳米晶超晶格。因此,发展一种简单有效的方法构建不同尺寸的单组分二元纳米晶超晶格具有重要意义。本文以十二烷硫醇稳定的3.7 nm金纳米晶为种子,在油胺中,采用种子生长法合成了6.0、7.3和9.6 nm的单分散金纳米晶。将油胺修饰的6.0、7.3和9.6 nm金纳米晶分别与3.7 nm金纳米晶以一定浓度比混合。采用溶剂蒸发法制备了AB2型(六边形AlB2结构),AB13型(NaZn13结构)和AB型(立方NaCl结构)的金二元纳米晶超晶格。本实验结果与相关的空间填充原理非常吻合。研究以单组分作为构建单元构筑的二元纳米晶超晶格结构与性能以及新型超材料的潜在发展具有重要意义。

关键词: 种子生长法, 金纳米晶, 自组装, 二元纳米晶超晶格, 结构

Abstract:

The assembly of two-component nanocrystals (NCs) such as metals, magnets, and semiconductors into binary nanocrystal superlattices (BNSLs) provides a fabrication route to novel classes of materials. BNSLs with certain structures can exhibit the combined and collective properties of their building blocks and are widespread in the fields of electronics and magnetic devices. As most studies have focused on combined two-component NCs of different sizes for self-assembling BNSLs, there are a few studies on single-component NCs of different sizes for the construction of BNSLs; this is especially true for Au NCs. Noble metallic Au NCs are an excellent candidate material because of their exceptional chemical stability, catalytic activity, process ability, and metallic nature; these characteristics provide them unique size-dependent optical and electronic properties as well as a wide variety of applications in sensing, imaging, electronic devices, medical diagnostics, and cancer therapeutics owing to their strong interactions with external electromagnetic fields. Therefore, it is important to develop a simple and efficient procedure to build BNSLs with different sizes of Au NCs. In our study, we synthesized monodispersed (size distribution < 10%) 6.0, 7.3, and 9.6 nm Au NCs using dodecanethiol-stabilized 3.7 nm Au NCs as seeds through a seed-growth method in oleylamine. The obtained Au NCs exhibited morphology and nanocrystallinity (single-domain and polycrystalline) similar to those of Au seeds. As the size of Au NCs increased from 3.7 to 6.0, 7.3, and 9.6 nm, the surface plasmon resonance peaks narrowed and indicated a red shift. The oleylamine-functionalized 6.0, 7.3, and 9.6 nm Au NCs were mixed with 3.7 nm Au NCs at certain concentration ratios. Au BNSLs with AB2 (hexagonal AlB2 structure), AB13 (NaZn13 structure), and AB (cubic NaCl structure) type were obtained through the solvent evaporation method. The (001) plane of the AlB2-type structure, (001) plane of the NaZn13-type structure, and (100) plane of NaCl-type structure superlattices were observed through transmission electron microscopy (TEM). The effective particle size ratios (γ= Dsmall/Dlarge) serve as the critical determining factor in the formation of the BNSLs. The effective particle size of NCs is equal to the sum of the metal core diameter and twice the thicknesses of the surface ligand. In our study, the effective particle size Dsmall (Au seed) is 5.7 nm; the effective particle sizes Dlarge (6.0, 7.3, and 9.6 nm Au NCs) are 9.0, 10.3, and 12.6 nm, respectively. The effective particle size ratios γ were therefore calculated to be 0.63, 0.55, and 0.45, respectively. The relevant space filling principle predicted the stability of the AlB2, NaZn13, and NaCl-type structures in the range of 0.482 < γ < 0.624, 0.54 < γ < 0.625, and γ < 0.458, respectively; the experimental results adequately matched the relevant space filling principle. The investigation of such a single nanocomponent as a building block is noteworthy with regard to the structures and properties of BNSLs as well as the potential development of novel meta-materials.

Key words: Seed growth method, Au nanocrystal, Self-assembly, Binary nanocrystal superlattice, Structure

MSC2000: 

  • O648