Figure 2: The Pb→Cd CE process in a 4.7-nm-sized PbS NC using different PSLs at different temperatures.
From: Atomistic understanding of cation exchange in PbS nanocrystals using simulations with pseudoligands
(a) Number of in-going Cd ions (red diamonds), remaining Pb ions (blue squares) and S ions (grey circles) in the parent PbS NCs as a function of time. MD simulations were performed at 500 K with non-preferential PSLs. (b,c) Time evolution of exchange ratio ρCd (the ratio of in-going Cd ions over the total number of cations in the NC). (b) Simulations performed at 500 K with different PSLs. A constant value of ρCd (∼0.2) for simulation with Cd-preferred PSLs indicates that CE did not take place. The low fraction of Cd ions corresponds to those Cd ions adsorbed at the NC surface. (c) Simulation performed using non-preferential PSLs at different temperatures. (d–i) Snapshots of the RS-(110) sections of the NCs in 100-ns MD simulations: (d) initial configuration; (e–i) final configurations of 100-ns simulations at 500 K with non-preferential PSLs (e), Cd-preferred PSLs (f), and Pb-preferred PSLs (g) and those with non-preferential PSLs at 400 K (h) and 600 K (i). The white, blue and red spheres represent S, Pb and Cd, respectively. (j–l) HRTEM images of PbE/CdE core/shell HNCs achieved by experimental CE, in a [110] projection. (j) A 9-nm-sized PbS/CdS core/shell HNC, image adapted with permission from (ref. 25) (copyright 2014 American Chemical Society). (k) A 5.6-nm-sized PbSe/CdSe core/shell HNC, image adapted with permission from (ref. 26) (copyright The Royal Society of Chemistry 2011). (l) A 6.6-nm-sized PbTe/CdTe core/shell HNC, image adapted with permission from (ref. 17) (copyright 2009 American Chemical Society).
