Yu Linghao, Li Hao, Shang Huan, Xing Pan, Zhou Biao, Chen Ziyue, Liu Xupeng, Zhang Hao, Shi Yanbiao, Zhang Lizhi
Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, Institute of Environmental & Applied Chemistry, College of Chemistry, Central China Normal University, Wuhan 430079, P. R. China.
School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
ACS Nano. 2023 Aug 8;17(15):15077-15084. doi: 10.1021/acsnano.3c04268. Epub 2023 Jul 25.
Two-dimensional (2D) layered photocatalysts with highly ordered out-of-plane symmetry usually display robust excitonic effects, thus being ineffective in driving catalytic reactions that necessitate unchained charge carriers. Herein, taking 2D BiOBr as a prototype model, we implement a superficial asymmetric [Br-Bi-O-Bi] stacking in the out-of-plane direction by selectively stripping off the top-layer Br of BiOBr. This local asymmetry disrupts the diagnostic confinement configuration of BiOBr to urge energetic exciton dissociation into charge carriers and further contributes to the emergence of a surface dipole field that powers the subsequent separation of transient electron-hole pairs. Distinct from the symmetric BiOBr, which activates O into O via an exciton-mediated energy transfer, surface asymmetric BiOBr favors selective O activation into ·O for a broad range of amine-to-imine conversions. Our work here not only presents a paradigm for asymmetric photocatalyst design but also expands the toolkit available for regulating exciton behaviors in semiconductor photocatalytic systems.
具有高度有序的面外对称性的二维（2D）层状光催化剂通常表现出强大的激子效应，因此在驱动需要非束缚电荷载流子的催化反应方面效率低下。在此，以二维BiOBr作为原型模型，我们通过选择性地剥离BiOBr的顶层Br，在面外方向实现了表面不对称的[Br-Bi-O-Bi]堆叠。这种局部不对称破坏了BiOBr的诊断性限制构型，促使高能激子解离为电荷载流子，并进一步促成了表面偶极场的出现，该场为随后瞬态电子-空穴对的分离提供动力。与通过激子介导的能量转移将O激活为O的对称BiOBr不同，表面不对称的BiOBr有利于在广泛的胺到亚胺转化中选择性地将O激活为·O。我们在此的工作不仅为不对称光催化剂设计提供了一个范例，还扩展了可用于调节半导体光催化系统中激子行为的工具集。
