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The unusual redox behaviour of ceria and its interaction with hydrogen
DOI:
10.1021/acs.chemmater.9b02854
Authors:
Adam H.
Clark
(University College London (UCL))
,
Kevin A.
Beyer
(Advanced Photon Source)
,
Shusaku
Hayama
(Diamond Light Source)
,
Timothy I.
Hyde
(Johnson Matthey Technology Centre)
,
Gopinathan
Sankar
(University College London)
Co-authored by industrial partner:
Yes
Type:
Journal Paper
Journal:
Chemistry Of Materials
State:
Published (Approved)
Published:
August 2019
Diamond Proposal Number(s):
16508
Abstract: The reaction between ceria and hydrogen has been subject to numerous theoretical and experimental studies due to its importance as a catalytic material. Here we present dynamic and reversible evolution of the cerium oxidation states observed through X-ray Absorption Spectroscopy experiments in addition to the investigation of associated lattice expansion and contraction through X-ray diffraction and PDF methods. Employing a novel calculation of the temperature dependence of the Gibbs free energy through consideration of the relationship between the instantaneous thermal lattice expansion and the rate of change of the cerium oxidation state, the unusual redox chemistry is reported here. This unusual behaviour is interpreted as due to the formation of a metastable cerium oxyhydride as suggested.
Subject Areas:
Chemistry
Instruments:
I20-Scanning-X-ray spectroscopy (XAS/XES)