Nanoscale Insights into the Hydrogenation Process of Layered α-MoO3

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• 作者：Weiguang Xie ; Mingze Su ; Zebo Zheng ; Yu Wang ; Li Gong ; Fangyan Xie ; Weihong Zhang ; Zhi Luo ; Jianyi Luo ; Pengyi Liu ; Ningsheng Xu ; Shaozhi Deng ; Huanjun Chen ; Jian Chen
• 刊名：ACS Nano
• 出版年：2016
• 出版时间：January 26, 2016
• 年：2016
• 卷：10
• 期：1
• 页码：1662-1670
• 全文大小：502K
• ISSN：1936-086X

文摘

The hydrogenation process of the layered α-MoO<sub>3sub> crystal was investigated on a nanoscale. At low hydrogen concentration, the hydrogenation can lead to formation of H<sub>xsub>MoO<sub>3sub> without breaking the MoO<sub>3sub> atomic flat surface. For hydrogenation with high hydrogen concentration, hydrogen atoms accumulated along the <101> direction on the MoO<sub>3sub>, which induced the formation of oxygen vacancy line defects. The injected hydrogen atoms acted as electron donors to increase electrical conductivity of the MoO<sub>3sub>. Near-field optical measurements indicated that both of the H<sub>xsub>MoO<sub>3sub> and oxygen vacancies were responsible for the coloration of the hydrogenated MoO<sub>3sub>, with the latter contributing dominantly. On the other hand, diffusion of hydrogen atoms from the surface into the body of the MoO<sub>3sub> will encounter a surface diffusion energy barrier, which was for the first time measured to be around 80 meV. The energy barrier also sets an upper limit for the amount of hydrogen atoms that can be bound locally inside the MoO<sub>3sub> via hydrogenation. We believe that our findings has provided a clear picture of the hydrogenation mechanisms in layered transition-metal oxides, which will be helpful for control of their optoelectronic properties via hydrogenation.