Flexible Cation Exchange Environment via Ligand-Free Metal Chalcogenide Thin Films

Abstract
Cation exchange (CE) has emerged as a premier postsynthetic method to carefully tune the chemical composition and properties of nanocrystals with excellent morphology retention. However, reaction conditions are typically dictated by the ubiquitous ligands bound to their surface, limiting their solubility and influencing the thermodynamics/kinetics of the reaction. To bypass these challenges, we report on CE reactions with Cu+, Ag+, Cu2+, Cd2+, Zn2+, and Mn2+ utilizing ligand-free CdS and CuxSey thin films as host templates. The exchange reactions could be performed sequentially or simultaneously (i.e., two guest cations) to access compositionally diverse products. The incorporation of cations on the host films was confirmed using SEM-EDS, XPS, and ICP-MS analyses, as well as tracking wavelength shifts in the UV–vis absorption spectra. The flexibility of this approach was demonstrated as reactions were carried out using an array of different guest precursor salts and solvents with a range of polarities. Moreover, the reactions were generalizable among selenide and sulfide films and proceeded under milder conditions in comparison with reported nanocrystal reactions. A ligand-free environment with flexible reaction conditions, as the work herein, could aid in deconvoluting the different factors involved in CE reactions and further expand its use for fundamental research and applications like photovoltaics, optoelectronics, and catalysis.
Description
This article was originally published in ACS Nanoscience Au. The version of record is available at: https://doi.org/10.1021/acsnanoscienceau.4c00023. © 2024 The Authors. Published by American Chemical Society. This publication is licensed under CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/) .
Keywords
cation exchange, chalcogenides, transition metals, thin films, ligands, HSAB
Citation
Lacey, Hannah R., Kevin D. Dobson, and Emil A. Hernández- Pagán. “Flexible Cation Exchange Environment via Ligand-Free Metal Chalcogenide Thin Films.” ACS Nanoscience Au, November 7, 2024. https://doi.org/10.1021/acsnanoscienceau.4c00023.