Structural evolution of reduced GeOx nanoparticles
Structural evolution of reduced GeOx nanoparticles
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还原GeOx纳米粒子的结构演化
DOI：
10.1039/c6cp07354a
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发表时间：
2017
影响因子：
3.3
通讯作者：
Liu Lijia
中科院分区：
文献类型：
--
作者：
McLeod John A.;Zhao Jia;Yang Linju;Liu Yi;Liu Lijia
GeOx纳米颗粒（NPs）在锂存储和光电子领域的应用日益受到关注。本文利用软x射线光谱学研究了化学还原法制备的GeOx纳米粒子，暴露于空气中或在N2下保留，然后在H2下在不同温度下退火。我们发现新鲜和空气暴露的GeOx NPs在退火下的演化有很大的不同。新生成的GeOx NPs开始时是一种非常无定形的GeOx和Ge的非均质混合物，在退火过程中，价带和导带边缘都发生演化。相比之下，暴露在空气中的GeOx NPs最初含有石英相的GeO2，在退火过程中，由于氧空位增加形成未占据的缺陷态，只有导带边缘发生变化（价带直到高温退火时才发生变化，此时几乎所有的GeO2都被去除）。这些发现提出了一种制备和退火策略，可用于定制GeOx NPs，以用于锂存储或光电应用。
GeOx nanoparticles (NPs) are of growing interest in lithium storage and optoelectronics. GeOx NPs prepared by chemical reduction, exposed to air or retained under N2, then annealed under H2 at various temperatures are studied herein using soft X-ray spectroscopy. We find that fresh and air-exposed GeOx NPs evolve rather differently under annealing. The fresh GeOx NPs start as a very amorphous heterogeneous mixture of GeOx and Ge, and during annealing both the valence band and conduction band edges evolve. In contrast, the air-exposed GeOx NPs initially contain quartz-phase GeO2, and during annealing only the conduction band edge evolves due to increased oxygen vacancies forming unoccupied defect states (the valence band does not change until annealing at high temperture, at which point almost all of the GeO2 is removed). These findings suggest a preparation and annealing strategy that could be used to tailor GeOx NPs for their intended use in lithium storage or optoelectronic applications.