The effect of exposed facets and oxygen vacancies on the catalytic activity of Pd_xCe_1−xO_2−δ nanorods for low-temperature CO oxidation has been investigated based on both experimental and theoretical methods. Pd_xCe_1−xO_2−δ nanorods with exposed {100} and {110} facets are more active than those with the {111} facet, and such superior active facets can become selectively accessible by modulating the calcination temperature. Moreover, a post H₂ reduction process further enhances the low temperature activity of Pd_xCe_1−xO_2−δ composites with a CO initial conversion temperature as low as 24 °C. It is suggested that the enhanced activity by the H₂ reduction process is mostly attributed to the promotion of oxygen vacancy concentration on the exposed facets. This is in reasonable agreement with the theoretical prediction that the CO oxidation proceeds via an oxygen vacancy-mediated Eley–Rideal mechanism on Pd_xCe_1−xO_2−δ nanorods. Our work highlights the importance of both exposed facets and oxygen vacancies on low temperature CO oxidation for Pd_xCe_1−xO_2−δ nanorod catalysts.

中文翻译：

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暴露面和氧空位对Pd _x Ce _{1− x} O _{2− δ}催化剂催化活性的影响：组合的实验和理论研究

基于实验和理论方法，研究了暴露面和氧空位对Pd _x Ce _{1− x} O ₂ − _δ纳米棒对低温CO氧化的催化活性的影响。暴露的{100}和{110}面的Pd _x Ce _{1- x} O _{2- δ}纳米棒比具有{111}面的Pd _x Ce _{1- x} O _{2- δ}纳米棒更具活性，并且可以通过调节煅烧温度来选择性地访问此类优越的活性面。而且，H _2后还原过程进一步增强了Pd _x Ce _{1- x} O _2-的低温活性。_δ复合材料的CO初始转化温度低至24°C。建议通过H ₂还原过程增强活性主要归因于暴露小平面上氧空​​位浓度的提高。这与理论上的预测是合理的一致，即CO氧化是通过氧空位介导的Eley-Rideal机理在Pd _x Ce _{1− x} O _{2− δ}纳米棒上进行的。我们的工作亮点暴露面和氧空位上低温CO氧化为钯两者的重要性_X的Ce _{1- X} ö _{2- δ}纳米棒催化剂。