U.S. Department of Energy Office of Scientific and Technical Information
Elucidating the Location of Cd2+ in Post-synthetically Treated InP Quantum Dots Using Dynamic Nuclear Polarization 31P and 113Cd Solid-State NMR Spectroscopy
Journal Article·· Journal of Physical Chemistry. C
Indium phosphide quantum dots (InP QD) are a promising alternative to traditional QD materials that contain toxic heavy elements such as lead and cadmium. However, InP QD obtained from colloidal synthesis are often plagued by poor photoluminescence quantum yields (PL-QYs). In order to improve the PL-QY of InP QD, a number of post-synthetic treatments have been devised. Recently, it has been shown that InP post-synthetically treated with Lewis acid metal divalent cations (M-InP) exhibit enhanced PL-QY; however, the molecular structure and mechanism behind the improved PL-QY are not fully understood. Here, to determine the surface structure of M-InP QD, dynamic nuclear polarization surface-enhanced nuclear magnetic resonance spectroscopy (DNP SENS) experiments were employed on a series of InP magic size clusters treated with Cd ions, InP QD, cadmium phosphide (Cd3P2) QD, and Cd-treated InP QD (Cd–InP QD). With the use of DNP SENS, we were able to obtain the 1D 31P and 113Cd NMR spectra, 113Cd{31P} rotational-echo double-resonance (REDOR) NMR spectra, and 31P{113Cd} dipolar heteronuclear multiple quantum correlation (D-HMQC) sequence. Changes in the phosphide 31P chemical shifts after Cd treatment provide indirect evidence that some Cd alloys into the sub-surface regions of the particle. DNP-enhanced 113Cd solid-state NMR spectra suggest that most Cd ions are coordinated by oxygen atoms from either carboxylate ligands or surface phosphate groups. 113Cd{31P} REDOR and 31P{113Cd} D-HMQC experiments confirm that a subset of Cd ions are located on the surface of Cd–InP QD and coordinated with phosphate groups.
Hanrahan, Michael P., et al. "Elucidating the Location of Cd<sup>2+</sup> in Post-synthetically Treated InP Quantum Dots Using Dynamic Nuclear Polarization <sup>31</sup>P and <sup>113</sup>Cd Solid-State NMR Spectroscopy." Journal of Physical Chemistry. C, vol. 125, no. 5, Jan. 2021. https://doi.org/10.1021/acs.jpcc.0c09601
Hanrahan, Michael P., Stein, Jennifer L., Park, Nayon, Cossairt, Brandi M., & Rossini, Aaron J. (2021). Elucidating the Location of Cd<sup>2+</sup> in Post-synthetically Treated InP Quantum Dots Using Dynamic Nuclear Polarization <sup>31</sup>P and <sup>113</sup>Cd Solid-State NMR Spectroscopy. Journal of Physical Chemistry. C, 125(5). https://doi.org/10.1021/acs.jpcc.0c09601
Hanrahan, Michael P., Stein, Jennifer L., Park, Nayon, et al., "Elucidating the Location of Cd<sup>2+</sup> in Post-synthetically Treated InP Quantum Dots Using Dynamic Nuclear Polarization <sup>31</sup>P and <sup>113</sup>Cd Solid-State NMR Spectroscopy," Journal of Physical Chemistry. C 125, no. 5 (2021), https://doi.org/10.1021/acs.jpcc.0c09601
@article{osti_1764374,
author = {Hanrahan, Michael P. and Stein, Jennifer L. and Park, Nayon and Cossairt, Brandi M. and Rossini, Aaron J.},
title = {Elucidating the Location of Cd<sup>2+</sup> in Post-synthetically Treated InP Quantum Dots Using Dynamic Nuclear Polarization <sup>31</sup>P and <sup>113</sup>Cd Solid-State NMR Spectroscopy},
annote = {Indium phosphide quantum dots (InP QD) are a promising alternative to traditional QD materials that contain toxic heavy elements such as lead and cadmium. However, InP QD obtained from colloidal synthesis are often plagued by poor photoluminescence quantum yields (PL-QYs). In order to improve the PL-QY of InP QD, a number of post-synthetic treatments have been devised. Recently, it has been shown that InP post-synthetically treated with Lewis acid metal divalent cations (M-InP) exhibit enhanced PL-QY; however, the molecular structure and mechanism behind the improved PL-QY are not fully understood. Here, to determine the surface structure of M-InP QD, dynamic nuclear polarization surface-enhanced nuclear magnetic resonance spectroscopy (DNP SENS) experiments were employed on a series of InP magic size clusters treated with Cd ions, InP QD, cadmium phosphide (Cd3P2) QD, and Cd-treated InP QD (Cd–InP QD). With the use of DNP SENS, we were able to obtain the 1D 31P and 113Cd NMR spectra, 113Cd{31P} rotational-echo double-resonance (REDOR) NMR spectra, and 31P{113Cd} dipolar heteronuclear multiple quantum correlation (D-HMQC) sequence. Changes in the phosphide 31P chemical shifts after Cd treatment provide indirect evidence that some Cd alloys into the sub-surface regions of the particle. DNP-enhanced 113Cd solid-state NMR spectra suggest that most Cd ions are coordinated by oxygen atoms from either carboxylate ligands or surface phosphate groups. 113Cd{31P} REDOR and 31P{113Cd} D-HMQC experiments confirm that a subset of Cd ions are located on the surface of Cd–InP QD and coordinated with phosphate groups.},
doi = {10.1021/acs.jpcc.0c09601},
url = {https://www.osti.gov/biblio/1764374},
journal = {Journal of Physical Chemistry. C},
issn = {ISSN 1932-7447},
number = {5},
volume = {125},
place = {United States},
publisher = {American Chemical Society},
year = {2021},
month = {01}}
USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division; Alfred P. Sloan Foundation; National Science Foundation (NSF)
Grant/Contract Number:
AC02-07CH11358
OSTI ID:
1764374
Report Number(s):
IS--J-10,405
Journal Information:
Journal of Physical Chemistry. C, Journal Name: Journal of Physical Chemistry. C Journal Issue: 5 Vol. 125; ISSN 1932-7447