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Temperature reversible synergistic formation of cerium oxyhydride and Au hydride: a combined XAS and XPDF study

DOI: 10.1039/D0CP00455C DOI Help

Authors: Adam H. Clark (University College London (UCL)) , Nadia Acerbi (University of Oxford; Johnson Matthey Technology Centre) , Philip A. Chater (Diamond Light Source) , Paul Collier (Johnson Matthey Technology Centre) , 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: Physical Chemistry Chemical Physics

State: Published (Approved)
Published: April 2020
Diamond Proposal Number(s): 15696 , 16508

Open Access Open Access

Abstract: In situ studies on the physical and chemical properties of Au in inverse ceria alumina supported catalysts have been conducted between 295 and 623 K using high energy resolved fluorescence detection X-ray absorption near edge spectroscopy and X-ray total scattering. Precise structural information is extracted on the metallic Au phase present in a 0.85 wt% Au containing inverse ceria alumina catalyst (ceria/Au/alumina). Herein evidence for the formation of an Au hydride species at elevated temperature is presented. Through modelling of total scattering data to extract the thermal properties of Au using Gr√ľneisen theory of volumetric thermal expansion it proposed that the Au Hydride formation occurs synergistally with the formation of a cerium oxyhydride. The temperature reversible nature, whilst remaining in a reducing atmosphere, demonstatrates the activation of hydrogen without consumption of oxygen from the supporting ceria lattice.

Subject Areas: Chemistry

Instruments: I15-1-X-ray Pair Distribution Function (XPDF) , I20-Scanning-X-ray spectroscopy (XAS/XES)