Probing the Surface Structure of Semiconductor Nanoparticles by DNP SENS with Dielectric Support Materials

Nathan Neale, Gregory Pach, Michael Hanrahan, Yunhua Chen, Rafael Blome-Fernandez, Jennifer Stein, Marquix Adamson, Brandi Cossairt, Javier Vela, Aaron Rossini

Research output: Contribution to journalArticlepeer-review

39 Scopus Citations


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 1-2 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 in comparison to standard protocols with mesoporous silica. Alternatively, precipitating the NPs as powders, mixing them with h-BN, and then impregnating the powdered mixture with radical solution leads to further 4-fold sensitivity enhancements by increasing the concentration of NPs in the final sample. This modified procedure provides a factor of 9 improvement in NMR sensitivity in comparison 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, subsurface, and core sites to be observed and assigned. For example, we demonstrate the acquisition of DNP-enhanced 2D 113Cd-113Cd correlation NMR experiments on CdS NPs and natural isotropic abundance 2D 13C-29Si HETCOR of functionalized Si NPs. These experiments provide a critical understanding of NP surface structures.

Original languageAmerican English
Pages (from-to)15532-15546
Number of pages15
JournalJournal of the American Chemical Society
Issue number39
StatePublished - 2 Oct 2019

Bibliographical note

Publisher Copyright:
© 2019 American Chemical Society.

NREL Publication Number

  • NREL/JA-5900-73949


  • nanoparticles
  • quantum dots
  • solar-photochemistry
  • solid-state NMR spectroscopy
  • surface characterization


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