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Title: Defect-induced anisotropic surface reactivity and ion transfer processes of anatase nanoparticles

Abstract

In this study, surface reactivity and ion transfer processes of anatase TiO2 nanocrystals were studied using Lithium bis(trifluoromethylsulfone)imide (LITFSI) as a probing molecule. The HRTEM analysis of synthesized anatase TiO2 reveals aggregated nanoparticles (average size ~8nm) with significant defects (holes and cracks). With the introduction of LiTFSI salt, the Li propensity towards defective surface along the anatase (100) plane is evident in XRD and HRTEM analysis. Ab initio molecular dynamics (AIMD) analysis corroborates the site-preferential interaction of Li+ cations with oxygen vacancies and the thermodynamically favourable transport through the (100) step edge plane. Using 7Li NMR chemical shift and relaxometry measurements, the Li+ cation near the TiO2 interface and the bulk LiTFSI phase were speciated, and subsequent diffusion properties were analyzed. The lower activation energy derived from NMR analysis reveals enhanced mobility of Li+ cations along the surface, in good agreement with AIMD calculations. On the other hand, the TFSI anion interaction with defect sites leads to CF3 bond dissociation and subsequent generation of carbonyl fluoride-type species. The multimodal spectroscopic analysis including NMR, EPR and XPS analysis confirms the decomposition of TFSI anions near the anatase surface. The reaction mechanism and electronic structure of interfacial constituents were simulated using AIMDmore » calculations. Ultimately, this work demonstrates the role of defects at the anatase nanoparticle surface on charge transfer and interfacial reaction processes.« less

Authors:
ORCiD logo; ; ; ; ; ; ORCiD logo; ORCiD logo; ORCiD logo
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1631805
Alternate Identifier(s):
OSTI ID: 1631198; OSTI ID: 1639158
Report Number(s):
PNNL-SA-150217
Journal ID: ISSN 2468-5194; S2468519420300501; 100290; PII: S2468519420300501
Grant/Contract Number:  
AC05-76RL01830
Resource Type:
Published Article
Journal Name:
Materials Today Chemistry
Additional Journal Information:
Journal Name: Materials Today Chemistry Journal Volume: 17 Journal Issue: C; Journal ID: ISSN 2468-5194
Publisher:
Elsevier
Country of Publication:
Country unknown/Code not available
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Surface radicals; solid state NMR; charge transfer; anion decomposition; molecular spectroscopy

Citation Formats

Lee, M. -S., Han, K. S., Lee, J., Shin, Y., Kaspar, T. C., Chen, Y., Engelhard, M. H., Mueller, K. T., and Murugesan, V.. Defect-induced anisotropic surface reactivity and ion transfer processes of anatase nanoparticles. Country unknown/Code not available: N. p., 2020. Web. https://doi.org/10.1016/j.mtchem.2020.100290.
Lee, M. -S., Han, K. S., Lee, J., Shin, Y., Kaspar, T. C., Chen, Y., Engelhard, M. H., Mueller, K. T., & Murugesan, V.. Defect-induced anisotropic surface reactivity and ion transfer processes of anatase nanoparticles. Country unknown/Code not available. https://doi.org/10.1016/j.mtchem.2020.100290
Lee, M. -S., Han, K. S., Lee, J., Shin, Y., Kaspar, T. C., Chen, Y., Engelhard, M. H., Mueller, K. T., and Murugesan, V.. Tue . "Defect-induced anisotropic surface reactivity and ion transfer processes of anatase nanoparticles". Country unknown/Code not available. https://doi.org/10.1016/j.mtchem.2020.100290.
@article{osti_1631805,
title = {Defect-induced anisotropic surface reactivity and ion transfer processes of anatase nanoparticles},
author = {Lee, M. -S. and Han, K. S. and Lee, J. and Shin, Y. and Kaspar, T. C. and Chen, Y. and Engelhard, M. H. and Mueller, K. T. and Murugesan, V.},
abstractNote = {In this study, surface reactivity and ion transfer processes of anatase TiO2 nanocrystals were studied using Lithium bis(trifluoromethylsulfone)imide (LITFSI) as a probing molecule. The HRTEM analysis of synthesized anatase TiO2 reveals aggregated nanoparticles (average size ~8nm) with significant defects (holes and cracks). With the introduction of LiTFSI salt, the Li propensity towards defective surface along the anatase (100) plane is evident in XRD and HRTEM analysis. Ab initio molecular dynamics (AIMD) analysis corroborates the site-preferential interaction of Li+ cations with oxygen vacancies and the thermodynamically favourable transport through the (100) step edge plane. Using 7Li NMR chemical shift and relaxometry measurements, the Li+ cation near the TiO2 interface and the bulk LiTFSI phase were speciated, and subsequent diffusion properties were analyzed. The lower activation energy derived from NMR analysis reveals enhanced mobility of Li+ cations along the surface, in good agreement with AIMD calculations. On the other hand, the TFSI anion interaction with defect sites leads to CF3 bond dissociation and subsequent generation of carbonyl fluoride-type species. The multimodal spectroscopic analysis including NMR, EPR and XPS analysis confirms the decomposition of TFSI anions near the anatase surface. The reaction mechanism and electronic structure of interfacial constituents were simulated using AIMD calculations. Ultimately, this work demonstrates the role of defects at the anatase nanoparticle surface on charge transfer and interfacial reaction processes.},
doi = {10.1016/j.mtchem.2020.100290},
journal = {Materials Today Chemistry},
number = C,
volume = 17,
place = {Country unknown/Code not available},
year = {2020},
month = {9}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
https://doi.org/10.1016/j.mtchem.2020.100290

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