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)