Li Cuncheng, Shuford Kevin L, Chen Minghai, Lee Eun Je, Cho Sung Oh
Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon, 305-701, Korea.
ACS Nano. 2008 Sep 23;2(9):1760-9. doi: 10.1021/nn800264q.
A straightforward and effective polyol route for the controllable synthesis of high-quality gold (Au) octahedra with uniform size is presented in an ethylene glycol solution. Large-scale Au octahedra with the size ranging from tens to hundreds of nanometers were selectively synthesized in high-yield. The surfaces of octahedral Au nanocrystals are smooth and correspond to {111} planes. Formation of Au nanooctahedra was attributed to the preferential adsorption of cationic surfactant poly(diallyldimethylammonium) chloride (PDDA) molecules on the {111} planes of Au nuclei that inhibited the growth rate along the <111> direction. The reduction rate of gold ions in the synthesis process can be rationally manipulated by acidic and basic solutions. This provides a facile and effective route to harvest Au octahedra with different dimensions. The synthetic strategy has the advantage of one-pot and requires no seeds, no foreign metal ions, and no pretreatment of the precursor, so that this is a practical method for controllable synthesis of Au octahedra. Size-dependent optical properties of Au octahedra were numerically and experimentally analyzed. The analysis shows that Au octahedra with sharp edges possess attractive optical properties, promising their applications to surface-enhancement spectroscopy, chemical or biological sensing, and the fabrication of nanodevices.
在乙二醇溶液中，提出了一种直接有效的多元醇路线，用于可控合成尺寸均匀的高质量金（Au）八面体。高产率地选择性合成了尺寸从几十到几百纳米的大规模金八面体。八面体金纳米晶体的表面光滑，对应于{111}平面。金纳米八面体的形成归因于阳离子表面活性剂聚二烯丙基二甲基氯化铵（PDDA）分子在金核的{111}平面上的优先吸附，这抑制了沿<111>方向的生长速率。合成过程中金离子的还原速率可通过酸性和碱性溶液合理控制。这为收获不同尺寸的金八面体提供了一种简便有效的途径。该合成策略具有一锅法的优点，无需种子、无外来金属离子且无需对前驱体进行预处理，因此是一种可控合成金八面体的实用方法。对金八面体的尺寸依赖性光学性质进行了数值和实验分析。分析表明，具有尖锐边缘的金八面体具有吸引人的光学性质，有望应用于表面增强光谱、化学或生物传感以及纳米器件的制造。
