Kang Zihan, Lin Enzhu, Qin Ni, Wu Jiang, Bao Dinghua
State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, China.
ACS Appl Mater Interfaces. 2022 Mar 9;14(9):11375-11387. doi: 10.1021/acsami.1c23282. Epub 2022 Feb 22.
Point defects in piezoelectric semiconductors play a significant role in regulating the piezocatalytic performance. However, the role of metal vacancies in piezocatalysis has been less explored than that of oxygen vacancies. Herein, BiWO (BWO) nanosheets with tunable Bi defects were synthesized using an ion exchange method. High-resolution transmission electron microscopy directly revealed the existence of Bi vacancies in the lattice of BWO nanosheets and the precipitation of Bi quasiparticles. The BWO nanosheets with the highest concentration of Bi vacancies exhibited an excellent decomposition efficiency (7.83 × 10 min) over rhodamine B under ultrasound. The phenomenon is mainly attributed to the increased charge carrier concentration as a consequence of defect energy levels. In addition, the significant enhancement of light absorption capacity caused by the surface plasmon resonance effect of quasiparticles indicates that Bi ions escape from the lattice and combine with free electrons around BWO to form Bi quantum dots, which function as electron traps to facilitate the separation of charge carriers during the piezocatalytic process. This work systematically reveals the essential affiliation of metal vacancies and surface metal clusters in piezocatalysts and verifies the significance of vacancy engineering in piezocatalytic application.
压电半导体中的点缺陷在调节压电催化性能方面起着重要作用。然而，金属空位在压电催化中的作用比氧空位的研究较少。在此，采用离子交换法合成了具有可调铋缺陷的BiWO（BWO）纳米片。高分辨率透射电子显微镜直接揭示了BWO纳米片晶格中铋空位的存在以及铋准粒子的析出。铋空位浓度最高的BWO纳米片在超声作用下对罗丹明B表现出优异的分解效率（7.83×10分钟）。该现象主要归因于缺陷能级导致的载流子浓度增加。此外，准粒子的表面等离子体共振效应引起的光吸收能力的显著增强表明，铋离子从晶格中逸出并与BWO周围的自由电子结合形成铋量子点，其作为电子陷阱，在压电催化过程中促进载流子的分离。这项工作系统地揭示了压电催化剂中金属空位与表面金属簇的本质联系，并验证了空位工程在压电催化应用中的重要性。
