skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Nanocrystals in Molten Salts and Ionic Liquids: Experimental Observation of Ionic Correlations Extending beyond the Debye Length

Abstract

The nature of the interface between the solute and the solvent in a colloidal solution has attracted attention for a long time. For example, the surface of colloidal nanocrystals (NCs) is specially created to impart colloidal stability in a variety of polar and nonpolar solvents. This work focuses on a special type of colloids where the solvent is a molten inorganic salt or organic ionic liquid. The stability of such colloids is difficult to rationalize because solvents with high density of mobile charges efficiently screen the electrostatic double-layer repulsion, and purely ionic molten salts represent an extreme case where the Debye length is only similar to 1 angstrom. We introduce a detailed investigation of NC dispersions in molten salts and ionic liquids using small-angle X-ray scattering (SAXS), atomic pair distribution function (PDF) analysis and molecular dynamics (MD) simulations. Our SAXS analysis confirms that a wide variety of NCs (Pt, CdSe/CdS, InP, InAs, ZrO2) can be uniformly dispersed in molten salts like AlCl3/NaCl/KCl (AlCl3/AlCl4-) and NaSCN/KSCN and in ionic liquids like 1-butyl-3-methylimidazolium halides (BMIM+X-, where X = Cl, Br, I). By using a combination of PDF analysis and molecular modeling, we demonstrate that the NC surface induces a solvent restructuring withmore » electrostatic correlations extending an order of magnitude beyond the Debye screening length. These strong oscillatory ion-ion correlations, which are not accounted by the traditional mechanisms of steric and electrostatic stabilization of colloids, offer additional insight into solvent-solute interactions and enable apparently "impossible" colloidal stabilization in highly ionized media.« less

Authors:
 [1];  [1]; ORCiD logo [1];  [2]; ORCiD logo [1];  [2]; ORCiD logo [2]; ORCiD logo [2];  [1]; ORCiD logo [3]
  1. Univ. of Chicago, IL (United States)
  2. Argonne National Lab. (ANL), Lemont, IL (United States)
  3. Univ. of Chicago, IL (United States); Argonne National Lab. (ANL), Lemont, IL (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF)
OSTI Identifier:
1558110
Grant/Contract Number:  
AC02-06CH11357; DMR-1420709; DMR-1611371
Resource Type:
Accepted Manuscript
Journal Name:
ACS Nano
Additional Journal Information:
Journal Volume: 13; Journal Issue: 5; Journal ID: ISSN 1936-0851
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; colloidal nanocrystals; ionic liquids; molecular dynamics simulations; molten salts; small angle x-ray scattering; solvent restructuring; x-ray pair distribution function

Citation Formats

Kamysbayev, Vladislav, Srivastava, Vishwas, Ludwig, Nicholas B., Borkiewicz, Olaf J., Zhang, Hao, Ilavsky, Jan, Lee, Byeongdu, Chapman, Karena W., Vaikuntanathan, Suriyanarayanan, and Talapin, Dmitri V. Nanocrystals in Molten Salts and Ionic Liquids: Experimental Observation of Ionic Correlations Extending beyond the Debye Length. United States: N. p., 2019. Web. https://doi.org/10.1021/acsnano.9b01292.
Kamysbayev, Vladislav, Srivastava, Vishwas, Ludwig, Nicholas B., Borkiewicz, Olaf J., Zhang, Hao, Ilavsky, Jan, Lee, Byeongdu, Chapman, Karena W., Vaikuntanathan, Suriyanarayanan, & Talapin, Dmitri V. Nanocrystals in Molten Salts and Ionic Liquids: Experimental Observation of Ionic Correlations Extending beyond the Debye Length. United States. https://doi.org/10.1021/acsnano.9b01292
Kamysbayev, Vladislav, Srivastava, Vishwas, Ludwig, Nicholas B., Borkiewicz, Olaf J., Zhang, Hao, Ilavsky, Jan, Lee, Byeongdu, Chapman, Karena W., Vaikuntanathan, Suriyanarayanan, and Talapin, Dmitri V. Tue . "Nanocrystals in Molten Salts and Ionic Liquids: Experimental Observation of Ionic Correlations Extending beyond the Debye Length". United States. https://doi.org/10.1021/acsnano.9b01292. https://www.osti.gov/servlets/purl/1558110.
@article{osti_1558110,
title = {Nanocrystals in Molten Salts and Ionic Liquids: Experimental Observation of Ionic Correlations Extending beyond the Debye Length},
author = {Kamysbayev, Vladislav and Srivastava, Vishwas and Ludwig, Nicholas B. and Borkiewicz, Olaf J. and Zhang, Hao and Ilavsky, Jan and Lee, Byeongdu and Chapman, Karena W. and Vaikuntanathan, Suriyanarayanan and Talapin, Dmitri V.},
abstractNote = {The nature of the interface between the solute and the solvent in a colloidal solution has attracted attention for a long time. For example, the surface of colloidal nanocrystals (NCs) is specially created to impart colloidal stability in a variety of polar and nonpolar solvents. This work focuses on a special type of colloids where the solvent is a molten inorganic salt or organic ionic liquid. The stability of such colloids is difficult to rationalize because solvents with high density of mobile charges efficiently screen the electrostatic double-layer repulsion, and purely ionic molten salts represent an extreme case where the Debye length is only similar to 1 angstrom. We introduce a detailed investigation of NC dispersions in molten salts and ionic liquids using small-angle X-ray scattering (SAXS), atomic pair distribution function (PDF) analysis and molecular dynamics (MD) simulations. Our SAXS analysis confirms that a wide variety of NCs (Pt, CdSe/CdS, InP, InAs, ZrO2) can be uniformly dispersed in molten salts like AlCl3/NaCl/KCl (AlCl3/AlCl4-) and NaSCN/KSCN and in ionic liquids like 1-butyl-3-methylimidazolium halides (BMIM+X-, where X = Cl, Br, I). By using a combination of PDF analysis and molecular modeling, we demonstrate that the NC surface induces a solvent restructuring with electrostatic correlations extending an order of magnitude beyond the Debye screening length. These strong oscillatory ion-ion correlations, which are not accounted by the traditional mechanisms of steric and electrostatic stabilization of colloids, offer additional insight into solvent-solute interactions and enable apparently "impossible" colloidal stabilization in highly ionized media.},
doi = {10.1021/acsnano.9b01292},
journal = {ACS Nano},
number = 5,
volume = 13,
place = {United States},
year = {2019},
month = {4}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 5 works
Citation information provided by
Web of Science

Save / Share:

Works referencing / citing this record:

Solvation of quantum dots in 1-alkyl-1-methylpyrrolidinium ionic liquids: toward stably luminescent composites
journal, January 2020

  • Nakashima, Takuya; Shigekawa, Kasumi; Katao, Shohei
  • Science and Technology of Advanced Materials, Vol. 21, Issue 1
  • DOI: 10.1080/14686996.2020.1735923