Oxygen vacancy formation and reduction properties of β-MnO2 grain boundaries and the potential for high electrochemical performance.
Oxygen vacancy formation and reduction properties of β-MnO2 grain boundaries and the potential for high electrochemical performance.
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DOI：
10.1021/am504351p
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发表时间：
2014-10
影响因子：
9.5
通讯作者：
J. Dawson;I. Tanaka
中科院分区：
文献类型：
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作者：
J. Dawson;I. Tanaka
近年来，金红石型（β-）MnO 2的纳米结构已被证明在许多技术应用中大大改善了其性质和性能。纳米结构材料的强电化学性质与显示有限的Li嵌入和电化学电容的本体材料之间的对比尚未完全理解。本文采用原子间相互作用势方法研究了β-MnO 2中四种倾斜晶界的结构、稳定性和催化性能。通过考虑每个晶界的γ-表面，我们能够找到每个晶界结构的最低能量配置。对于每个晶界，我们观察到的氧空位的能量显着降低和周围的晶界相比，散装β-MnO 2和散装状结构的晶界细胞。还考虑了Mn（4+）还原为Mn（3+），并且再次显示在边界处是优选的。这些能量表明在β-MnO 2的晶界处具有潜在的更高的催化活性。结果也被放置到最近的β-MnO 2表面的计算的背景下，以产生更详细的了解到这一重要的现象。
In recent years, the nanostructuring of rutile (β-)MnO2 has been shown to vastly improve its properties and performance in a number of technological applications. The contrast between the strong electrochemical properties of the nanostructured material and the bulk material that shows limited Li intercalation and electrochemical capacitance is not yet fully understood. In this work, we investigate the structure, stability and catalytic properties of four tilt grain boundaries in β-MnO2 using interatomic potential methods. By considering the γ-surfaces of each of the grain boundaries, we are able to find the lowest energy configurations for each grain boundary structure. For each grain boundary, we observe a significant decrease in the oxygen vacancy energies in and around the grain boundaries compared to bulk β-MnO2 and also the bulk-like structures in the grain boundary cells. The reduction of Mn(4+) to Mn(3+) is also considered and again is shown to be preferable at the boundaries. These energies suggest a potentially higher catalytic activity at the grain boundaries of β-MnO2. The results are also placed into context with recent calculations of β-MnO2 surfaces to produce a more detailed understanding into this important phenomenon.