title: Atomistic understanding of cation exchange in PbS nanocrystals using simulations with pseudoligands.
abstract: Cation exchange is a powerful tool for the synthesis of nanostructures such as core-shell nanocrystals, however, the underlying mechanism is poorly understood. Interactions of cations with ligands and solvent molecules are systematically ignored in simulations. Here, we introduce the concept of pseudoligands to incorporate cation-ligand-solvent interactions in molecular dynamics. This leads to excellent agreement with experimental data on cation exchange of PbS nanocrystals, whereby Pb ions are partially replaced by Cd ions from solution. The temperature and the ligand-type control the exchange rate and equilibrium composition of cations in the nanocrystal. Our simulations reveal that Pb ions are kicked out by exchanged Cd interstitials and migrate through interstitial sites, aided by local relaxations at core-shell interfaces and point defects. We also predict that high-pressure conditions facilitate strongly enhanced cation exchange reactions at elevated temperatures. Our approach is easily extendable to other semiconductor compounds and to other families of nanocrystals.
authors.affiliation: Process and Energy Department, Delft University of Technology, Leeghwaterstraat 39, 2628CB Delft, The Netherlands.
authors.forename: Zhaochuan
authors.identifier: http://orcid.org/0000-0002-2626-7411
authors.initials: Z
authors.lastname: Fan
authors.affiliation: Process and Energy Department, Delft University of Technology, Leeghwaterstraat 39, 2628CB Delft, The Netherlands.
authors.forename: Li-Chiang
authors.identifier: http://orcid.org/0000-0002-2821-9501
authors.initials: LC
authors.lastname: Lin
authors.affiliation: Process and Energy Department, Delft University of Technology, Leeghwaterstraat 39, 2628CB Delft, The Netherlands.
authors.forename: Wim
authors.initials: W
authors.lastname: Buijs
authors.affiliation: Process and Energy Department, Delft University of Technology, Leeghwaterstraat 39, 2628CB Delft, The Netherlands.
authors.forename: Thijs J H
authors.initials: TJH
authors.lastname: Vlugt
authors.affiliation: Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 5, 3584CC Utrecht, The Netherlands.
authors.forename: Marijn A
authors.initials: MA
authors.lastname: van Huis