Title: Does H 2 Temperature‐Programmed Reduction Always Probe Solid‐State Redox Chemistry? The Case of Pt/CeO 2

Journal Article · · Angewandte Chemie
ORCiD logo [1];  [2]
  1. Department of Chemical Engineering University of California, Santa Barbara Santa Barbara CA 93106-5080 United States, Department of Applied Chemistry Kyungpook National University Daegu 41566 Republic of Korea
  2. Department of Chemical Engineering University of California, Santa Barbara Santa Barbara CA 93106-5080 United States

Abstract Redox reactions on the surface of transition metal oxides are of broad interest in thermo, photo, and electrocatalysis. H 2 temperature‐programmed reduction (H 2 ‐TPR) is commonly used to probe oxide reducibility by measuring the rate of H 2 consumption during temperature ramps, assuming that this rate is controlled by oxide reduction. However, oxide reduction involves several elementary steps, such as H 2 dissociation and H‐spillover, before surface reduction and H 2 O formation occur. In this study, we evaluated the kinetics of H 2 consumption over CeO 2 and Pt/CeO 2 with varying Pt loadings and structures to identify the elementary steps probed by H 2 ‐TPR. Literature often attributes changes in H 2 ‐TPR characteristics with Pt addition to increased CeO 2 reducibility. However, our analysis revealed that the H 2 consumption rate is measurement of the rate of H‐spillover at Pt‐CeO 2 interfaces and is determined by the concentration of Pt species on Pt nanoclusters that dissociate H 2 . Therefore, lower temperature H 2 consumption observed with Pt addition does not indicate higher CeO 2 reducibility. Measurements on samples with mixtures of Pt single‐atoms and nanoclusters demonstrated that H 2 ‐TPR can effectively quantify dilute Pt nanocluster concentrations, suggesting caution in directly linking H 2 ‐TPR characteristics to oxide reducibility while highlighting alternative material insights that can be gleaned.

Sponsoring Organization:
USDOE
Grant/Contract Number:
SC0021124
OSTI ID:
2524091
Journal Information:
Angewandte Chemie, Journal Name: Angewandte Chemie Journal Issue: 2 Vol. 137; ISSN 0044-8249
Publisher:
Wiley Blackwell (John Wiley & Sons)Copyright Statement
Country of Publication:
Germany
Language:
English

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