title: Nanoscale Insights into the Hydrogenation Process of Layered α-MoO3.
abstract: The hydrogenation process of the layered α-MoO3 crystal was investigated on a nanoscale. At low hydrogen concentration, the hydrogenation can lead to formation of HxMoO3 without breaking the MoO3 atomic flat surface. For hydrogenation with high hydrogen concentration, hydrogen atoms accumulated along the <101> direction on the MoO3, which induced the formation of oxygen vacancy line defects. The injected hydrogen atoms acted as electron donors to increase electrical conductivity of the MoO3. Near-field optical measurements indicated that both of the HxMoO3 and oxygen vacancies were responsible for the coloration of the hydrogenated MoO3, with the latter contributing dominantly. On the other hand, diffusion of hydrogen atoms from the surface into the body of the MoO3 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 MoO3 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.
authors.forename: Weiguang
authors.initials: W
authors.lastname: Xie
authors.forename: Mingze
authors.initials: M
authors.lastname: Su
authors.forename: Zebo
authors.initials: Z
authors.lastname: Zheng
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.forename: Li
authors.initials: L
authors.lastname: Gong
authors.forename: Fangyan
authors.initials: F
authors.lastname: Xie
authors.forename: Weihong
authors.initials: W
authors.lastname: Zhang
authors.forename: Zhi
authors.initials: Z
authors.lastname: Luo
authors.affiliation: School of Applied Physics and Materials, Wuyi University , Jiangmen 529020, China.
authors.forename: Jianyi
authors.initials: J
authors.lastname: Luo
authors.forename: Pengyi
authors.initials: P
authors.lastname: Liu
authors.forename: Ningsheng
authors.initials: N
authors.lastname: Xu
authors.forename: Shaozhi
authors.initials: S
authors.lastname: Deng
authors.forename: Huanjun
authors.initials: H
authors.lastname: Chen
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
keywords: MoO3; hydrogen bronzes; hydrogenation; oxygen vacancies; transition metal oxides