Dynamic Nuclear Polarization NMR Spectroscopy for Atomistic Understanding of Colloidal Nanocrystal Surfaces

Laura Piveteau^a^,^b, Ta-Chung Ong^a, Brennan J. Walder^c, Aaron J. Rossini^c, Dmitry Dirin^a, Lindon Emsley^c, Christophe Copéret^a, Maksym V. Kovalenko^a^,^b

^aETH Zürich, Department of Chemistry and Applied Biosciences, Switzerland, Switzerland

^bEMPA - Swiss Federal Laboratories for Materials Science and Technology, Überland Strasse, 129, Dübendorf, Switzerland

^cEPFL École Polytechnique Fédérale de Lausanne, Department of Chemical Sciences and Engineering, Switzerland, Switzerland

Materials for Sustainable Development Conference (MATSUS)
Proceedings of nanoGe September Meeting 2017 (NFM17)

SE1: Fundamental Processes in Semiconductor Nanocrystals

Barcelona, Spain, 2017 September 4th - 9th

Organizers: Arjan Houtepen and Zeger Hens

Poster, Laura Piveteau, 155
Publication date: 20th June 2016

Nuclear magnetic resonance (NMR) is an attractive non-invasive analytical method to study nanocrystals (NCs) since it can access the ligands of colloidal NCs (solution NMR) as well as the crystal surface and core in NC powders (solid-state NMR). However, NMR is suffering of inherently poor sensitivity, especially when it comes to isotopes other than ¹H, ¹³C, ¹⁹F and ³¹P, rendering most NC materials difficult or not accessible by NMR.

We have presented in earlier work that dynamic nuclear polarization (DNP) is an efficient enhancement technique for NMR signal from NCs, especially for surface-located species, which are particularly low abundant compared to the NC-core atoms.¹ We developed a novel, universally applicable, extremely simple and inexpensive methodology for sample preparation to overcome the low signal intensity.² Further, we found 2D-spectroscopy to be an elegant tool to tackle the difficulties of spectra interpretation, by visualizing interactions² or by increasing resolution through the isolation of line broadening effects.³

NMR therefore permits to selectively study NC-core, NC-surface or capping ligands, may they be of organic or inorganic nature. Additionally, atomistic-level insights into nature and distribution of species present in NCs can be obtained. Their composition, chemical dynamics and electronic structure can be studied, which are inaccessible through any other known single analytical technique.

1. Protesescu, L.; Rossini, A. J.; Kriegner, D.; Valla, M.; de Kergommeaux, A.; Walter, M.; Kravchyk, K. V.; Nachtegaal, M.; Stangl, J.; Malaman, B.; Reiss, P.; Lesage, A.; Emsley, L.; Copéret, C.; Kovalenko, M. V. ACS Nano 2014, 8, (3), 2639-2648.

2. Piveteau, L.; Ong, T.-C.; Rossini, A. J.; Emsley, L.; Copéret, C.; Kovalenko, M. V. Journal of the American Chemical Society 2015, 137, (43), 13964-13971.

3. Piveteau, L.; Ong, T.-C.; Walder, B. J.; Emsley, L.; Copéret, C.; Kovalenko, M.V. Manuscript in preparation.

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