Persistence of Ce3+ Species on the Surface of Ceria during Redox Cycling: A Modulated Chemical Excitation Investigation

IF 2.9 3区化学 Q3 CHEMISTRY, PHYSICAL

Physical Chemistry Chemical Physics Pub Date : 2025-05-16 DOI:10.1039/d5cp01283j

Cyril Hachemi, Hadi Dib, Mourad Debbichi, Michael Badawi, Calley Eads, Maya Ibrahim, Stéphane Loridant, Jan Knudsen, Helena Kaper, Luis Cardenas

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引用次数: 0

Abstract

Operando Resonant Photoelectron Spectroscopy (RPES) combined with Modulated Chemical Excitation revealed the dynamic evolution of Ce³⁺ and Ce⁴⁺ redox states at the surface of CeO₂ during the CO oxidation reaction. Using alternating CO and O₂ pulses as chemically modulated signals, we monitored the surface states in the valence band region, unveiling the evolution of electronic structure during the catalytic process. The analysis with different gas flow ratios revealed that under CO-rich conditions (CO:O₂ ≥ 1), only partial conversion from Ce³⁺ to Ce⁴⁺ occurred. In contrast, complete Ce³⁺ to Ce⁴⁺ conversion was achieved when pulsing O₂ into O₂-rich environments. Furthermore, we find that intermediate oxygen species, such as peroxo and OH, impact the conversion of Ce³⁺ and Ce⁴⁺. These oxygenated species coexist between 330 °C and 360 °C in pure O₂, while above 390 °C only OH groups remain stable on the ceria surface.

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氧化还原循环过程中Ce3+在铈表面的持久性：一种调制化学激发研究

Operando谐振光电子能谱（RPES）结合调制化学激发揭示了CO氧化反应过程中CeO2表面Ce3+和Ce4+氧化还原态的动态演变。利用CO和O2交替脉冲作为化学调制信号，我们监测了价带区的表面状态，揭示了催化过程中电子结构的演变。不同气体流量比的分析表明，在CO-富条件下（CO:O2≥1），Ce3+仅部分转化为Ce4+。相比之下，当脉冲O2进入富O2环境时，Ce3+完全转化为Ce4+。此外，我们发现中间氧，如过氧和OH，会影响Ce3+和Ce4+的转化。在纯O2中，在330°C到360°C之间，这些氧化基团共存，而在390°C以上，只有OH基团在氧化铈表面保持稳定。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Physical Chemistry Chemical Physics 化学-物理：原子、分子和化学物理

CiteScore

5.50

自引率

9.10%

发文量

2675

审稿时长

2.0 months

期刊介绍： Physical Chemistry Chemical Physics (PCCP) is an international journal co-owned by 19 physical chemistry and physics societies from around the world. This journal publishes original, cutting-edge research in physical chemistry, chemical physics and biophysical chemistry. To be suitable for publication in PCCP, articles must include significant innovation and/or insight into physical chemistry; this is the most important criterion that reviewers and Editors will judge against when evaluating submissions. The journal has a broad scope and welcomes contributions spanning experiment, theory, computation and data science. Topical coverage includes spectroscopy, dynamics, kinetics, statistical mechanics, thermodynamics, electrochemistry, catalysis, surface science, quantum mechanics, quantum computing and machine learning. Interdisciplinary research areas such as polymers and soft matter, materials, nanoscience, energy, surfaces/interfaces, and biophysical chemistry are welcomed if they demonstrate significant innovation and/or insight into physical chemistry. Joined experimental/theoretical studies are particularly appreciated when complementary and based on up-to-date approaches.