Atomic-scale observation of pressure-dependent reduction dynamics of W18O49 nanowires using environmental TEM

Zhengfei Zhang; Liping Sheng; Lu Chen; Ze Zhang; Yong Wang

doi:10.1039/c7cp03071a

Atomic-scale observation of pressure-dependent reduction dynamics of W₁₈O₄₉ nanowires using environmental TEM

Phys Chem Chem Phys. 2017 Jun 28;19(25):16307-16311. doi: 10.1039/c7cp03071a.

Authors

Zhengfei Zhang¹, Liping Sheng, Lu Chen, Ze Zhang, Yong Wang

Affiliation

¹ Center of Electron Microscopy and State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, P. R. China. [email protected].

PMID: 28608883
DOI: 10.1039/c7cp03071a

Abstract

The real-time observation of structural evolution of materials can provide critical information for understanding their reduction mechanisms under different environments. Herein, we report the atomic-scale observation of the reduction dynamics of W₁₈O₄₉ nanowires (NWs) using environmental transmission electron microscopy. Intriguingly, the reduction pathway is found to be affected by oxygen pressure. Under high oxygen pressure (∼0.095 Pa), a W₁₈O₄₉ NW epitaxially transforms into a WO₂ NW via mass transport across the interface between (010)_{W₁₈O₄₉} and (101)_WO₂. While under low oxygen pressure (∼0.0004 Pa), the transformation follows the sequence of W₁₈O₄₉(NW) → WO₂(NW) → β-W(nanoparticles), which is identified as a new reduction pathway. These findings reveal the pressure-dependent reduction and a new transformation pathway, and extend our current understanding of the reduction dynamics of metal oxides.