A thorough understanding of Bi2Se3 surface etching is crucial for elucidating mechanisms, precise surface function adjustment, and advancing optoelectronic/catalytic applications, as this typical topological insulator has unique surface-dependent properties. However, the dynamic etching mechanisms essential for functionality tuning remain poorly understood due to conventional technique limitations. Here, in situ transmission electron microscopy (TEM) and liquid cell electron microscopy techniques (LC-TEM/LC-SEM) were employed to track Bi2Se3 etching kinetics in vacuum and liquid environments. It was suggested that electron-beam irradiation effectively promotes the evolution of the inherent void defect within the Bi2Se3 material. In the liquid phase, a high electron dose rate (25 e/(Å2·s)) not only triggers the etching of Bi2Se3 nanosheets but also promotes the precipitation of bismuth(III) compounds. Both the chemical blocking effect of the potential surface oxide layer and the structural defect characteristics of the screw dislocations significantly influence etching site selection (>80% etching ratio at edges vs 2Se3 and analogous layered topological insulators, which is pivotal for optimizing the performance of next-generation optoelectronic devices and heterogeneous catalysts. This work further helps to elucidate the universal mechanisms of oxidative etching of layered nanomaterial surfaces.
Sheng et al. (2026) studied this question.