ae9b01747_si_001.pdf (1.45 MB)
Probing the Crystal and Electronic Structures of Molybdenum Oxide in Redox Process: Implications for Energy Applications
journal contribution
posted on 2019-10-16, 22:44 authored by Huayu Peng, Weiwei Meng, He Zheng, Yanjie Wei, Huaping Sheng, Huihui Liu, Lei Li, Guangyu Wen, Shuangfeng Jia, Luying Li, Jianbo WangKnowledge
regarding the phase and valence state evolution of molybdenum
(Mo) and its oxides during the redox reaction is essential for advancing
their energy applications (e.g., electrocatalysis), which unfortunately
remains largely unexplored. Herein, the effects of atomic and electronic
structures on the electrocatalytic performance of Mo/oxides core–shell
structures are investigated on the basis of the combination of ex situ and in situ experiments. First,
a two-step reaction pathway is revealed during the oxidation of nanoscale
Mo: the formation of amorphous MoO3 (A-MoO3)
shells followed by the nucleation of crystalline α-MoO3. It is shown that the electrocatalytic performance of A-MoO3 is superior to that of α-MoO3, mainly due
to more catalytically active sites in the former material. Furthermore,
in situ transmission electron microscopy observations show that the
A-MoO3 shell can be rapidly reduced into metallic MoO2 under reductive environment, which is likely to occur during
the hydrogen evolution reaction measurement. Our in-depth characterization
may contribute to the thorough and comprehensive understanding of
the structural transition in Mo and its oxides during oxidative and
reductive environments and thus serves as a reference for understanding
the structure–property interplay for real energy applications.