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Fast MAS 1H NMR Study of Water Adsorption and Dissociation on the (100) Surface of Ceria Nanocubes: A Fully Hydroxylated, Hydrophobic Ceria Surface

Fast MAS 1H NMR Study of Water Adsorption and Dissociation on the (100) Surface of Ceria Nanocubes: A Fully Hydroxylated, Hydrophobic Ceria Surface

Authors :
Banghao Chen
Edward W. Hagaman
Lance W. Gill
Steven H. Overbury
Ariana Beste
Amanda K. P. Mann
Meijun Li
Source :
The Journal of Physical Chemistry C. 121:7450-7465
Publication Year :
2017
Publisher :
American Chemical Society (ACS), 2017.

Abstract

1H nuclear magnetic resonance (NMR) spectroscopy was used to study hydroxylic surface species on ceria nanocubes, a crystalline, high-surface-area CeO2 that presents mostly (100) facets. Water adsorption and desorption experiments in combination with fast magic angle spinning (MAS, 20–40 kHz) 1H NMR provide high-resolution 1H spectra that allow the observation of ten resonance bands (water or hydroxyl) on or under the (100) surface. Assignments were made using a combination of adsorption and temperature-programmed desorption, quantitative spin counting, deuterium exchange, spin–lattice (T1) and spin–spin (T2) relaxation, and DFT calculations. In air, the (100) surface exists as a fully hydroxylated surface. Water adsorption and dissociation on dry ceria surfaces occur first at oxygen vacancies, but Ce3+ centers are not required since water dissociation is barrier-less on the fully oxidized surface. Surface −OH functionality occurs in two resolved bands representing isolated −OH (1 ppm) and hydrogen-bonded...

Details

ISSN :
19327455 and 19327447
Volume :
121
Database :
OpenAIRE
Journal :
The Journal of Physical Chemistry C
Accession number :
edsair.doi...........0e9a387373b7deb71bfe994369241bf9
Full Text :
https://doi.org/10.1021/acs.jpcc.6b12375