Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova, Italy.
Nano Lett. 2011 Nov 9;11(11):4964-70. doi: 10.1021/nl202927a. Epub 2011 Sep 30.
We demonstrate that it is possible to convert CdSe nanocrystals of a given size, shape (either spherical or rod shaped), and crystal structure (either hexagonal wurtzite, i.e., hexagonal close packed (hcp), or cubic sphalerite, i.e., face-centered cubic (fcc)), into ZnSe nanocrystals that preserve all these characteristics of the starting particles (i.e., size, shape, and crystal structure), via a sequence of two cation exchange reactions, namely, Cd(2+) ⇒Cu(+) ⇒Zn(2+). When starting from hexagonal wurtzite CdSe nanocrystals, the exchange of Cd(2+) with Cu(+) yields Cu(2)Se nanocrystals in a metastable hexagonal phase, of which we could follow the transformation to the more stable fcc phase for a single nanorod, under the electron microscope. Remarkably, these metastable hcp Cu(2)Se nanocrystals can be converted in solution into ZnSe nanocrystals, which yields ZnSe nanocrystals in a pure hcp phase.
我们证明，通过一系列的两步阳离子交换反应，即 Cd(2+) ⇒Cu(+) ⇒Zn(2+)，可以将具有特定尺寸、形状（球形或棒形）和晶体结构（六方纤锌矿，即六方密堆积（hcp），或闪锌矿，即面心立方（fcc））的 CdSe 纳米晶转化为 ZnSe 纳米晶，且保留起始颗粒的所有这些特性（即尺寸、形状和晶体结构）。当从六方纤锌矿 CdSe 纳米晶开始时，Cd(2+)与 Cu(+)的交换生成亚稳六方相的 Cu(2)Se 纳米晶，我们可以在电子显微镜下观察到其中单个纳米棒向更稳定的 fcc 相的转变。值得注意的是，这些亚稳的 hcp Cu(2)Se 纳米晶可以在溶液中转化为 ZnSe 纳米晶，从而得到纯 hcp 相的 ZnSe 纳米晶。
