Skip to main content
Article
Probing the Surface Structure of Semiconductor Nanoparticles by DNP SENS with Dielectric Support Materials
Journal of the American Chemical Society
  • Michael P. Hanrahan, Iowa State University and Ames Laboratory
  • Yunhua Chen, Iowa State University and Ames Laboratory
  • Rafael Blome-Fernández, Iowa State University
  • Jennifer L. Stein, University of Washington
  • Gregory F. Pach, National Renewable Energy Laboratory
  • Marquix A. S. Adamson, Iowa State University
  • Nathan R. Neale, National Renewable Energy Laboratory
  • Brandi M. Cossairt, University of Washington
  • Javier Vela, Iowa State University and Ames Laboratory
  • Aaron J. Rossini, Iowa State University and Ames Laboratory
Document Type
Article
Disciplines
Publication Version
Submitted Manuscript
Publication Date
8-28-2019
DOI
10.1021/jacs.9b05509
Abstract

Surface characterization is crucial for understanding how the atomic-level structure affects the chemical and photophysical properties of semiconducting nanoparticles (NPs). Solid-state nuclear magnetic resonance spectroscopy (NMR) is potentially a powerful technique for the characterization of the surface of NPs, but it is hindered by poor sensitivity. Dynamic nuclear polarization surface enhanced NMR spectroscopy (DNP SENS) has previously been demonstrated to enhance the sensitivity of surface-selective solid-state NMR experiments by one to two orders of magnitude. Established sample preparations for DNP SENS experiments on NPs require the dilution of the NPs on mesoporous silica. Using hexagonal boron nitride (h-BN) to disperse the NPs doubles DNP enhancements and absolute sensitivity as compared to standard protocols with mesoporous silica. Alternatively, precipitating the NPs as powders, mixing them with h-BN, then impregnating the powdered mixture with radical solution leads to further four-fold sensitivity enhancements by increasing the concentration of NPs in the final sample. This modified procedure provides a factor 9 improvement in NMR sensitivity as compared to previously established DNP SENS procedures, enabling challenging homonuclear and heteronuclear 2D NMR experiments on CdS, Si and Cd3P2 NPs. These experiments allow NMR signals from the surface, sub-surface and core sites to be observed and assigned. For example, we demonstrate that the acquisition of DNP-enhanced 2D 113Cd113Cd correlation NMR experiments on CdS NPs and natural isotropic abundance 2D 13C29Si HETCOR of functionalized Si NPs. These experiments provide a critical understanding of NP surface structures.

Comments

This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in Journal of the American Chemical Society, copyright © American Chemical Society after peer review. To access the final edited and published work see DOI: 10.1021/jacs.9b05509. Posted with permission.

Copyright Owner
American Chemical Society
Language
en
File Format
application/pdf
Citation Information
Michael P. Hanrahan, Yunhua Chen, Rafael Blome-Fernández, Jennifer L. Stein, et al.. "Probing the Surface Structure of Semiconductor Nanoparticles by DNP SENS with Dielectric Support Materials" Journal of the American Chemical Society Vol. 141 Iss. 39 (2019) p. 15532 - 15546
Available at: http://works.bepress.com/aaron-rossini/64/