Anisotropic Cation Exchange in PbSe/CdSe Core/Shell Nanocrystals of Different Geometry

被引：145

作者：

Casavola, Marianna ^{[1
]}

van Huis, Marijn A. ^{[2
,3
]}

Bals, Sara ^{[2
]}

Lambert, Karel ^{[4
]}

Hens, Zeger ^{[4
]}

Vanmaekelbergh, Daniel ^{[1
]}

机构：

[1] Univ Utrecht, Debye Inst Nanomat Sci, NL-3508 TA Utrecht, Netherlands

[2] Univ Antwerp, EMAT, B-2020 Antwerp, Belgium

[3] Delft Univ Technol, Kavli Inst Nanosci, NL-2628 CJ Delft, Netherlands

[4] Univ Ghent, B-9000 Ghent, Belgium

来源：

CHEMISTRY OF MATERIALS | 2012年 / 24卷 / 02期

关键词：

core/shell nanocrystals; cation exchange; near-infrared-active nanocrystals; HAADF-STEM; PbSe/CdSe; COLLOIDAL NANOCRYSTALS; NANORODS; CDSE;

D O I：

10.1021/cm202796s

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

We present a study of Cd2+-for-Pb2+ exchange in PbSe nanocrystals (NCs) with cube, star, and rod shapes. Prolonged temperature-activated cation exchange results in PbSe/CdSe heterostructured nanocrystals (HNCs) that preserve their specific overall shape, whereas the PbSe core is strongly faceted with dominance of {111} facets. Hence, cation exchange proceeds while the Se anion lattice is preserved, and well-defined {111}/{111} PbSe/CdSe interfaces develop. Interestingly, by quenching the reaction at different stages of the cation exchange new structures have been isolated, such as core-shell nanorods, CdSe rods that contain one or two separated PbSe dots and fully zinc blende CdSe nanorods. The crystallographically anisotropic cation exchange has been characterized by a combined HRTEM/HAADF-STEM study of heterointerface evolution over reaction time and temperature. Strikingly, Pb and Cd are only intermixed at the PbSe/CdSe interface. We propose a plausible model for the cation exchange based on a layer-by-layer replacement of Pb2+ by Cd2+ enabled by a vacancy-assisted cation migration mechanism.

引用

页码：294 / 302

页数：9