Quantification of a PbClx Shell on the Surface of PbS Nanocrystals

Published

August 5, 2019

Author(s)

Samuel W. Winslow, Yun Liu, James W. Swan, William A. Tisdale

Abstract

Differences between the properties of PbS nanocrystals prepared using a large excess of PbCl₂ and those prepared using other Pb sources have led to speculation that a thin PbCl_x shell may be present on the surface of PbCl₂-derived PbS nanocrystals. However, characterization of this chloride layer has proved challenging due to the poor contrast provided by electron and X-ray scattering probes. Here, we show that small angle neutron scattering (SANS) provides the compositional sensitivity needed to unambiguously quantify the PbCl_x shell that is present on the surface of PbCl_x-derived PbS nanocrystals. Using a charge balanced, self-consistent model form factor, the scattering contribution of a 0.3nm thick surface PbCl_x layer is parsed separately from ligand carboxylate head groups and PbS in the core. Global fitting of the SANS data across a solvent deuteration series enabled unique determination of each material. These results were corroborated by quantitative nuclear magnetic resonance (NMR) and energy-dispersive X-ray spectroscopy (EDS). This work resolves a discrepancy in reported sizing curves for PbS nanocrystals prepared by different syntheses, and further demonstrates the power of SANS in resolving molecular structure in soft and hybrid nanomaterials.

Citation

ACS Materials Letters

Volume

1

Issue

2

Pub Type

Journals

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Keywords

nanocrystal, small angle neutron scattering

Citation

Winslow, S. , Liu, Y. , Swan, J. and Tisdale, W. (2019), Quantification of a PbCl_x Shell on the Surface of PbS Nanocrystals, ACS Materials Letters, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=928220 (Accessed October 7, 2024)