Zhang Liqiu, Jang Hee-Jeong, Yoo Sungjae, Cho Sanghyun, Won Ji Hye, Liu Lichun, Park Sungho
Department of Chemistry and Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea. College of Biological, Chemical Sciences and Engineering, Jiaxing University, Jiaxing 314001, People's Republic of China.
Nanotechnology. 2018 Sep 14;29(37):375602. doi: 10.1088/1361-6528/aace99. Epub 2018 Jun 22.
Site-selective synthesis of nanostructures is an important topic in the nanoscience community. Normally, the difference between seeds and deposition atoms in terms of crystallinity triggers the deposition atoms to grow initially at the specific site of nucleation. It is more challenging to control the deposition site of atoms that have the same composition as the seeds because the atoms tend to grow epitaxially, covering the whole surface of the seed nanoparticles. Gold (Au) nano-octahedrons used as seeds in this study possess obvious hierarchical surface energies depending on whether they are at vertices, edges, or terraces. Although vertices of Au nano-octahedrons have the highest surface energy, it remains a challenge to selectively deposit Au atoms at the vertices but not at the edges and faces; this selectivity is required to meet the ever-increasing demands of engineered nanomaterial properties. This work demonstrates an easy and robust method to precisely deposit Au nanoparticles at the vertices of Au nano-octahedrons via wet-chemical seed-mediated growth. The successful synthesis of octahedral Au tip-blobbed nanoparticles (Oh Au TBPs) benefited from the cooperative use of thin silver (Ag) layers at the surface of Au nano-octahedron seeds and iodide ions in the Au growth solution. As-synthesized Au nanostructures (i.e., Au TBPs) gave rise to hybrid optical properties, as evidenced from the UV-vis-NIR extinction spectra, in which a new extinction peak appeared after Au nanoparticles were formed at the vertices of Au nano-octahedrons. A sensitivity evaluation toward dielectric media of a mixture of dimethyl sulfoxide and water suggested that Au TBPs were more optically sensitive compared to the original Au nano-octahedrons. The method demonstrated in this work is promising in the synthesis of advanced Au nanostructures with hybrid optical properties for versatile applications, by engineering the surface energy of vertex-bearing Au nanostructures to trigger site-selective overgrowth of congener Au atoms.
纳米结构的位点选择性合成是纳米科学界的一个重要课题。通常，晶种与沉积原子在结晶度方面的差异会促使沉积原子最初在成核的特定位置生长。对于与晶种具有相同组成的原子，控制其沉积位点更具挑战性，因为这些原子倾向于外延生长，覆盖晶种纳米颗粒的整个表面。本研究中用作晶种的金（Au）纳米八面体根据其位于顶点、边缘还是平台具有明显的分级表面能。尽管金纳米八面体的顶点具有最高的表面能，但在顶点而非边缘和面选择性地沉积金原子仍然是一个挑战；这种选择性是满足对工程纳米材料性能不断增长的需求所必需的。这项工作展示了一种简单且稳健的方法，通过湿化学晶种介导生长，将金纳米颗粒精确地沉积在金纳米八面体的顶点。八面体金尖端带团块纳米颗粒（Oh Au TBPs）的成功合成得益于在金纳米八面体晶种表面协同使用薄银（Ag）层以及金生长溶液中的碘离子。合成的金纳米结构（即Au TBPs）呈现出混合光学性质，紫外 - 可见 - 近红外消光光谱证明了这一点，其中在金纳米八面体的顶点形成金纳米颗粒后出现了一个新的消光峰。对二甲基亚砜和水混合物的介电介质的灵敏度评估表明，与原始的金纳米八面体相比，Au TBPs具有更高的光学灵敏度。通过设计带有顶点的金纳米结构的表面能来触发同属金原子的位点选择性过度生长，本工作中展示的方法在合成具有混合光学性质以用于多种应用的先进金纳米结构方面具有广阔前景。
