用于氧还原反应的高活性外延La(1-x)Sr(x)MnO3表面：电荷转移的作用
Highly Active Epitaxial La(1-x)Sr(x)MnO3 Surfaces for the Oxygen Reduction Reaction: Role of Charge Transfer.
作者信息
Stoerzinger Kelsey A, Lü Weiming, Li Changjian, Venkatesan T, Shao-Horn Yang
机构信息
∥NUSNNI-Nanocore, ⊥National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS), #Department of Physics, and ∇Department of Electrical and Computer Engineering, National University of Singapore, Singapore.
出版信息
J Phys Chem Lett. 2015 Apr 16;6(8):1435-40. doi: 10.1021/acs.jpclett.5b00439. Epub 2015 Apr 2.
Most studies of oxide catalysts for the oxygen reduction reaction (ORR) use oxide powder, where the heterogeneity of exposed surfaces and the composite nature of electrodes limit fundamental understanding of the reaction mechanism. We present the ORR activity of epitaxially oriented La(1-x)Sr(x)MnO3 surfaces and investigate, by varying Sr substitution, the relationship between the role of charge transfer and catalytic activity in an alkaline environment. The activity is greatest for La(1-x)Sr(x)MnO3 with 33% Sr, containing mixed Mn(3+/4+), and the (110) and (111) orientations display comparable activities to that of the (001). Electrochemical measurements using the facile redox couple Fe(CN)6 illustrate that increasing ORR activity trends with faster charge-transfer kinetics, indicating the importance of facile charge transfer at the oxide/water interface and mixed Mn valence in promoting ORR kinetics.
大多数关于氧还原反应（ORR）的氧化物催化剂研究使用氧化物粉末，其中暴露表面的不均匀性和电极的复合性质限制了对反应机理的基本理解。我们展示了外延取向的La(1-x)Sr(x)MnO3表面的ORR活性，并通过改变Sr取代量，研究了碱性环境中电荷转移作用与催化活性之间的关系。对于含33% Sr、具有混合Mn(3+/4+)的La(1-x)Sr(x)MnO3，其活性最高，且(110)和(111)取向的活性与(001)相当。使用简便的氧化还原对Fe(CN)6进行的电化学测量表明，ORR活性增加的趋势与更快的电荷转移动力学相关，这表明在促进ORR动力学方面，氧化物/水界面处的便捷电荷转移和混合Mn价态很重要。
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