巨大的现场电子熵增强了二氧化铈用于水分解的性能。,Nature Communications

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巨大的现场电子熵增强了二氧化铈用于水分解的性能。
Nature Communications ( IF 14.7 ) Pub Date : 2017-08-18 , DOI: 10.1038/s41467-017-00381-2
S. Shahab Naghavi , Antoine A. Emery , Heine A. Hansen , Fei Zhou , Vidvuds Ozolins , Chris Wolverton

先前的研究表明，对于两步热化学水分解循环，大的固态还原熵会提高诸如二氧化铈之类的金属氧化物的热力学效率。在这种情况下，由氧化物中的非化学计量比引起的构型熵一直是大多数先前工作的重点。在这里，我们报告了一种不同的熵源，即现场电子构型熵，它是由镧系元素f轨道的轨道和自旋角动量之间的耦合引起的。我们发现，在所有镧系元素中，现场电子构型熵都相当大，对于Ce ⁴⁺ / Ce ^3+，每个氧空位的最大值达到≈4.7k _B减少。二氧化铈中独特而又大的正熵源说明了其在高温催化氧化还原反应（如水分解）中的优异性能。我们的计算还表明，二氧化ter具有很高的电子熵，因此也可能是太阳热化学反应的潜在候选者。还原的固态熵增加了二氧化铈对两步热化学水分解的热力学效率。在这里，作者报告了一个巨大而又不同的熵源，即现场电子构型熵是由f轨道的轨道和自旋角动量之间的耦合引起的。

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Giant onsite electronic entropy enhances the performance of ceria for water splitting.

Previous studies have shown that a large solid-state entropy of reduction increases the thermodynamic efficiency of metal oxides, such as ceria, for two-step thermochemical water splitting cycles. In this context, the configurational entropy arising from oxygen off-stoichiometry in the oxide, has been the focus of most previous work. Here we report a different source of entropy, the onsite electronic configurational entropy, arising from coupling between orbital and spin angular momenta in lanthanide f orbitals. We find that onsite electronic configurational entropy is sizable in all lanthanides, and reaches a maximum value of ≈4.7 k _B per oxygen vacancy for Ce⁴⁺/Ce³⁺ reduction. This unique and large positive entropy source in ceria explains its excellent performance for high-temperature catalytic redox reactions such as water splitting. Our calculations also show that terbium dioxide has a high electronic entropy and thus could also be a potential candidate for solar thermochemical reactions.Solid-state entropy of reduction increases the thermodynamic efficiency of ceria for two-step thermochemical water splitting. Here, the authors report a large and different source of entropy, the onsite electronic configurational entropy arising from coupling between orbital and spin angular momenta in f orbitals.

更新日期：2017-08-17

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