Surface Defect Chemistry and Electronic Structure of Pr0.1Ce0.9O2−δ Revealed in Operando,Chemistry of Materials

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Surface Defect Chemistry and Electronic Structure of Pr0.1Ce0.9O2−δ Revealed in Operando
Chemistry of Materials ( IF 7.2 ) Pub Date : 2018-03-27 00:00:00 , DOI: 10.1021/acs.chemmater.7b05129
Qiyang Lu _{1,

2} , Gulin Vardar _{1,

3} , Maximilian Jansen _{1,

3} , Sean R. Bishop _{1,

2} , Iradwikanari Waluyo ₄ , Harry L. Tuller ₂ , Bilge Yildiz _{1,

2,

3}

Affiliation

Understanding the surface defect chemistry of oxides under functional operating conditions is important for providing guidelines for improving the kinetics of electrochemical reactions. Ceria-based oxides have applications in solid oxide fuel/electrolysis cells, thermo-chemical water splitting, catalytic convertors, and red-ox active memristive devices. The surface defect chemistry of doped ceria in the regime of high oxygen pressure, pO₂, approximating the operating conditions of fuel cell cathodes at elevated temperatures, has not yet been revealed. In this work, we investigated the Pr_0.1Ce_0.9O_2−δ (PCO) surface by in operando X-ray photoelectron and absorption spectroscopic methods. We quantified the concentration of reduced Pr³⁺, at the near-surface region of PCO as a function of electrochemical potential, corresponding to a wide range of effective pO₂. We found that the Pr³⁺ concentration at the surface was significantly higher than the values predicted from bulk defect chemistry. This finding indicates a lower effective defect formation energy at the surface region compared with that in the bulk. In addition, the Pr³⁺ concentration has a weaker dependence on pO₂ compared to that in the bulk.

中文翻译：

在操作中显示的Pr _0.1 Ce _0.9 O _2−δ的表面缺陷化学和电子结构

了解功能操作条件下氧化物的表面缺陷化学对于提供改善电化学反应动力学的指导方针很重要。基于二氧化铈的氧化物可用于固体氧化物燃料/电解池，热化学水分解，催化转化器和氧化还原活性忆阻装置。尚未揭示高氧压力下的掺杂二氧化铈的表面缺陷化学性质p O ₂，其近似于燃料电池阴极在高温下的工作条件。在这项工作中，我们调查了镨_0.1的Ce _0.9 ø _2-δ（PCO）表面通过在operandoX射线光电子和吸收光谱法。我们在PCO的近表面区域对还原的Pr ³⁺的浓度进行了定量，该浓度是电化学电位的函数，对应于宽范围的有效p O ₂。我们发现表面的Pr ³⁺浓度明显高于根据体缺陷化学预测的值。该发现表明，与本体相比，在表面区域的有效缺陷形成能量更低。另外，与本体中的相比，Pr ³⁺浓度对p O _2的依赖性更弱。

更新日期：2018-03-27

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