Unexpected Two-Dimensional Polarons Induced by Oxygen Vacancies in Layered Structure MoO<sub>3–<i>x</i></sub>
Xiaoxi Guan, Jiaheng Wang, Jiaheng Wang, Zheng He, Weiwei Meng, Renhui Jiang, Ligong Zhao, Tianlong Huang, Peili Zhao, Shuangfeng Jia, Jianbo Wang, Jianbo Wang
Abstract
Unveiling the effects of oxygen vacancies on the structural stability of layered α-MoO 3 is critical for optimizing its physical and chemical properties. Herein, we present experimental evidence regarding the phase stability of α-MoO 3 with ∼2% oxygen vacancy concentrations. Interestingly, we report a previously ignored oxygen-deficient orthorhombic MoO 3– x phase in space group Cmcm . Further density functional theory calculations reveal a detailed phase transition mechanism from α-MoO 3 to MoO 3– x . More importantly, we demonstrate that two-dimensional (2D) large polarons must exist to stabilize the MoO 3– x crystal structure. 2D large polarons are suspected to exist in numerous quasi-2D systems but have never been found in layered α-MoO 3 or other molybdenum oxides. Our work contributes to a basic understanding of the polaronic behavior in MoO 3– x and may broaden the application realm of molybdenum oxides.