Evolution of the Atomic Structure of Ceria-Supported Platinum Nanocatalysts: Formation of Single Layer Platinum Oxide and Pt–O–Ce and Pt–Ce Linkages

• Published in: Journal of physical chemistry. C Vol. 120; no. 49; pp. 28057 - 28066
• Main Authors: Avakyan, Leon A, Kolpacheva, Natalia A, Paramonova, Ekaterina V, Singh, Jagdeep, Hartfelder, Urs, van Bokhoven, Jeroen A, Bugaev, Lusegen A
• Format: Journal Article
• Language: English
• Published: American Chemical Society 15-12-2016
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.6b09824

Depending on platinum loading and gas environment vastly different platinum structures in Pt/ceria were observed by Pt L3-edge extended X-ray absorption (EXAFS) and X-ray absorption near-edge (XANES) spectroscopies. Calcination of highly loaded platinum (4 wt %) yielded stacked layers of α-PtO2. The low platinum-loaded sample (2 wt %), obtained by leaching, consisted of a single layer of α-PtO2 bonded to the support by Pt–O–Ce linkages. Reduction of the platinum oxide by exposure to a carbon monoxide and hydrogen (PROX) gas mixture led to complete metal reduction at temperatures above 540 K. Under these conditions platinum–cerium bonds with a distance of 2.4 Å were detected and particles of 0.8 and 0.6 nm for the high-loaded and low-loaded Pt/ceria samples, respectively.