Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan.
Chemistry. 2011 Aug 22;17(35):9746-52. doi: 10.1002/chem.201101155. Epub 2011 Jul 18.
We report the development of a seed-mediated and iodide-assisted method for the synthesis of monodisperse gold nanocrystals with systematic shape evolution from rhombic dodecahedral to octahedral structures. Particle growth is complete in 15 min at room temperature, so the process is fast and energy-efficient. By progressively increasing the volume of KI used in a growth solution while keeping the amount of ascorbic acid added constant, nanocrystals with morphologies that vary from rhombic dodecahedral to rhombicuboctahedral, edge- and corner-truncated octahedral, corner-truncated octahedral, and octahedral structures were synthesized. The nanocrystals are monodisperse in size and readily form self-assembled structures on substrates. By simply adjusting the volume of gold seed solution added to a growth solution, particle sizes of the octahedral gold nanocrystals can be tuned with average opposite corner-to-corner distances of 42, 48, 54, 60, 68, 93, 107, and 125 nm. In the presence of HAuCl(4), iodide may act as a reducing agent. Variation of its volume in the solution may slightly modulate the reduction rate and affect the final crystal morphology. Intermediate structures collected during crystal growth reveal the presence of many twisted structures that surround a developing nanocrystal core. This nanocrystal growth mechanism and the less important role of surfactant in directing the polyhedral nanocrystal morphology is discussed.
我们报告了一种种子介导和碘化物辅助的方法，用于合成具有从菱形十二面体到八面体结构的系统形态演变的单分散金纳米晶体。在室温下，15 分钟内完成颗粒生长，因此该过程快速且节能。通过在生长溶液中逐渐增加 KI 的体积，同时保持添加的抗坏血酸的量不变，可以合成形貌从菱形十二面体到菱面体八面体、棱边和角截断的八面体、角截断的八面体和八面体的纳米晶体。纳米晶体尺寸均匀，易于在基底上自组装形成结构。通过简单地调整添加到生长溶液中的金种子溶液的体积，可以调节八面体金纳米晶体的粒径，平均对角到对角距离为 42、48、54、60、68、93、107 和 125nm。在 HAuCl(4)存在下，碘化物可能充当还原剂。其在溶液中的体积变化可能会略微调节还原速率并影响最终晶体形态。在晶体生长过程中收集的中间结构显示出许多扭曲结构的存在，这些结构围绕着一个正在发育的纳米晶核。讨论了这种纳米晶体生长机制和表面活性剂在指导多面体纳米晶体形态方面的次要作用。
