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Atomistic Observation of Temperature-Dependent Defect Evolution within Sub-stoichiometric WO 3- x Catalysts.

Xiaoyuan YeChanggeng WeiSikang XueWandong XingXiaocong LiangHongbo NieMin ShenYong DuJinshui ZhangXinchen WangWei LinZhiyang Yu
Published in: ACS applied materials & interfaces (2021)
Tunable crystalline defects endow WO 3- x catalysts with extended functionalities for a broad range of photo- and electric-related applications. However, direct visualization of the defect structures and their evolution mechanism is lacking. Herein, aberration-corrected and in situ transmission electron microscopy was complemented by theoretical calculations to investigate the effect of temperature on the defect evolution behavior during hydrogenation treatment. Low processing temperature (100-300 °C) leads to the occurrence of randomly distributed oxygen vacancies within WO 3- x nanosheets. At higher temperatures, oxygen vacancies become highly mobile and aggregate into stacking faults. Planar defects are prone to nucleate at the surface and develop in a zigzag form at 400 °C, while treating at 500 °C promotes the growth of {200}-type stacking faults. Our work clearly establishes that the atomic configuration of the defects in WO 3- x samples could be manipulated by regulating the hydrogenation temperature. This study not only expands our understanding of the structure-function relationships of sub-stoichiometric tungsten oxides but also unlocks their full potential as advanced catalysts by tuning stoichiometry in a controlled manner.
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