Self-Aligned BiFeO <sub>3</sub> Polarization Vector Induced by MnO <sub>6</sub> Octahedral Jahn–Teller Distortion for Enhanced Photocatalytic CO <sub>2</sub> Reduction
Na Liang, Qian Jiang Zhu, Mengpei Jiang, Xianglin Hou, Zhiyu Shao, Shao-Hua Wang, Yuzhou He, Wanyu Zhang, Renlian Huang, Yaowen Zhang, Huijuan Yue, Xiaofeng Wu, Jun Chen, Keke Huang, Shouhua Feng
Abstract
High Resolution Image Download MS PowerPoint Slide Precise modulation of polarization vector alignment through chemical synthesis strategies remains challenging for designing high-performance ferroelectric photocatalysts. Herein, the proposed Jahn–Teller distortion-mediated mechanism resolves the polarization disorder by elongating MnO 6 octahedra to drive the coordinated displacement of neighboring atoms along a uniform direction without an external electric field. Specifically, the localized charge of Mn is modulated via redistribution with oxygen ligands, thereby achieving an optimal electronic configuration (Mn t 2g 3 e g 1 ) that induces a maximal Jahn–Teller distortion, as confirmed by X-ray absorption and Raman spectroscopies. Notably, atomic pair distribution functions demonstrate that the structural evolution of the Jahn–Teller unit directly propels displacement of Fe and O atoms along the [001̅] crystallographic direction, which intensifies the asymmetric deformation of FeO 6 octahedra, forming an oriented polarization. Consequently, the rapid separation of carriers driven by the depolarization electric field motivates the conversion from CO 2 to CO with a yield of 30.51 μmol g –1 h –1 under pure water conditions, which is almost five times that of the original BiFeO 3 . This study proposes an innovative strategy to modulate the polarization vector via Jahn–Teller distortion, offering insights into the development of ferroelectric photocatalysts from the perspective of the electronic structure.