Quantification of a PbClx Shell on the Surface of PbS Nanocrystals
Samuel W. Winslow, Yun Liu, James W. Swan, William A. Tisdale
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 PbClx 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 PbClx shell that is present on the surface of PbClx-derived PbS nanocrystals. Using a charge balanced, self-consistent model form factor, the scattering contribution of a 0.3nm thick surface PbClx 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.
, Liu, Y.
, Swan, J.
and Tisdale, W.
Quantification of a PbCl<sub>x</sub> Shell on the Surface of PbS Nanocrystals, ACS Materials Letters, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=928220
(Accessed December 6, 2023)