Origin and Dynamics of Oxygen Storage/Release in a Pt/Ordered CeO₂–ZrO₂ Catalyst Studied by Time‐Resolved XAFS Analysis

Abstract

Electronic and structural dynamics of an industrially relevant Pt/CeO2–ZrO2 catalyst with an ordered arrangement of Ce and Zr ions during oxygen storage/release processes at 573–773 K were studied in real time by time‐resolved energy‐dispersive XAFS at the Zr K edge and Ce L3 edge (see experimental setup). On the basis of these results, the roles of Ce and Zr ions in the function of the mixed‐oxide catalyst were elucidated.

Maximizing the Localized Relaxation: The Origin of the Outstanding Oxygen Storage Capacity of κ‐Ce2Zr2O8

“…This is consistent with the experimental results [13] that k-Ce 2 Ze 2 O 8 phase possesses 89 % cerium efficiency, whereas t-Ce 2 Ze 2 O 8 has an efficiency of 52 %.…”

“…X-ray adsorption fine structure (XAFS) and X-ray diffraction (XRD) analyses showed that under the reducing conditions, the oxygen vacancy forms at O b (Figure 1 b). [13,19] This result appears to contradict chemical intuition: Herein, we investigate the oxygen vacancy formation in kCe 2 Zr 2 O 8 using density functional calculations to uncover the origin of the high OSC of k-Ce 2 Zr 2 O 8 . The calculations were performed with the GGA-PW91 functional using the VASP code.…”

In Situ Time-Resolved Energy-Dispersive XAFS Study on Reduction Behavior of Pt Supported on TiO2 and Al2O3

“…Recently, some groups reported the DXAFS studies on kinetics and dynamics of catalysis in several synchrotron radiation sources in the world [16]. Iwasawa et al [17] reported the kinetics and the dynamics studies using DXAFS analysis on the reduction processes of Cu cations in ZSM-5, the structural changes in metal clusters [18,19], the oxygen storage/release in a Pt/ordered CeO 2 -ZrO 2 catalyst [20], and the surface changes on the Pt/C cathode in a fuel cell [21]. Okumura et al [22,23] clarified the structural changes of Pd species in the Heck reaction over a zeolitesupported Pd cluster catalyst by the DXAFS analysis.…”

Key Factors Affecting the Performance and Durability of Cathode Electrocatalysts in Polymer Electrolyte Fuel Cells Characterized by In Situ Real Time and Spatially Resolved XAFS Techniques

“…In situ time-resolved XAFS technique in real-time processes enables to determine reaction sequences and structural changes at active metal sites/ensembles in dynamic catalytic processes involving adsorption, diffusion and reactions as reported by our groups in 2000-2011 [27][28][29][30][31][32][33][34][35]. We carried out the world's first successful quick-XAFS (QXAFS) observation and thorough analysis of structural changes of a PEFC Pt/C cathode electrocatalyst in voltage cycling processes (0.4 ¡ 1.0 V vs RHE) and succeeded in deciding six elementary reaction steps and their rate constants in 2007 [14].…”