Surface Reduced Manganese States as a Source of Oxygen Reduction Activity in BaMnO3,Advanced Functional Materials

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Surface Reduced Manganese States as a Source of Oxygen Reduction Activity in BaMnO3
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2023-03-15 , DOI: 10.1002/adfm.202214883
Lucia Hughes _{1,

2,

3} , Ahin Roy _{1,

2,

3,

4} , Clive Downing ₁ , Michelle P. Browne _{2,

5} , Ainur Zhussupbekova _{3,

6} , Igor V. Shvets _{3,

6} , Valeria Nicolosi _{1,

2,

3}

Affiliation

In relation to perovskites, tweaking the oxidation state of the B-site cation is fundamental to controlling the catalytic activity of these materials, thus necessitating a complete characterization of surface oxidation states. Herein, using a combination of atomic-scale imaging and spectroscopic techniques, structure-property correlation in barium manganese oxide (BaMnO₃) is established for the oxygen reduction reaction (ORR). Electron energy loss spectroscopy (EELS) on the synthesized BaMnO₃ find the rods to contain an amorphous surface layer with reduced Mn³⁺ states compared to Mn⁴⁺ states in the bulk. Consequently, the BaMnO₃ rods show electrocatalytic activity for the ORR, which originates from the presence of Mn³⁺ at the rod surface. Furthermore, heating of the samples in air at 300 and 800 °C results in a decrease in the number of Mn³⁺ states, and thus lowering of the ORR activity. This study represents a step-stone study in understanding the mechanism of ORR activity and its association to the Mn³⁺ state at the perovskite's surface, opening up possibilities for further surface engineering and tuning catalytic properties.

中文翻译：

表面还原锰态作为 BaMnO3 中氧还原活性的来源

关于钙钛矿，调整 B 位阳离子的氧化态是控制这些材料催化活性的基础，因此需要对表面氧化态进行完整表征。在此，结合使用原子级成像和光谱技术，建立了氧化钡 (BaMnO _{3 ) 中氧还原反应 (ORR) 的结构-性质相关性。}对合成的 BaMnO ₃进行的电子能量损失光谱 (EELS) 发现，与块体中的Mn ⁴⁺态相比，棒包含 Mn ^{3+态减少的非晶表面层。}因此，BaMnO ₃棒显示出对 ORR 的电催化活性，这源于棒表面存在 Mn ^{3+ 。}^{此外，在 300 和 800 °C 的空气中加热样品会导致 Mn 3+}态数量减少，从而降低 ORR 活性。这项研究代表了了解 ORR 活性机制及其与钙钛矿表面Mn ³⁺态关联的阶梯式研究，为进一步的表面工程和调节催化性能开辟了可能性。

更新日期：2023-03-15

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