Less Is More. Cation Exchange and the Chemistry of the Nanocrystal Surface
详细信息 查看全文
- 作者：Yolanda Justo ; Laxmi Kishore Sagar ; Stijn Flamee ; Qiang Zhao ; Andr茅 Vantomme ; Zeger Hens
- 刊名：ACS Nano
- 出版年：2014
- 出版时间：August 26, 2014
- 年：2014
- 卷：8
- 期：8
- 页码：7948-7957
- 全文大小：846K
- ISSN：1936-086X
文摘
We link the extent of Pb for Cd cation exchange reactions in PbS colloidal quantum dots (QDs) to their surface chemistry. Using PbS QDs with either a full or a partial surface coverage by excess Pb, we demonstrate the central role played by vacant cation sites on the QD surface. They facilitate the adsorption of cations from solution, and they act as a source of vacancies needed for the transport of cations through the crystal lattice. This model explains our finding that the cation exchange reaction runs to completion when using a low Cd excess in the exchange bath, while it is impeded by a high Cd excess. Whereas in the latter case, the QD surface is poisoned by surface Cd, the former conditions provide the mixture of surface Cd and vacant surface sites the exchange reaction needs to proceed. This understanding provides a missing link needed to build a unifying mechanistic picture of cation exchange reactions at nanocrystals.