Direct Fabrication of Atomically Defined Pores in MXenes Using Feedback-Driven STEM

Area of Science:

• Materials Science
• Nanotechnology
• Surface Science

Background:

• Controlled nanopore fabrication in 2D materials is essential for advanced membranes used in ion transport and nanofiltration.
• Existing methods like plasma etching and direct irradiation have limitations.
• Aberration-corrected scanning transmission electron microscopy (STEM) offers atomic precision for both fabrication and imaging.

Purpose of the Study:

• To develop an automated nanopore fabrication method using STEM with real-time atomic visualization.
• To investigate the mechanistic understanding of electron beam-induced transformations during nanopore creation.
• To explore the influence of temperature on nanopore fabrication in MXene Ti3C2Tx.

Main Methods:

• Utilized aberration-corrected scanning transmission electron microscopy (STEM) for automated nanopore fabrication and real-time atomic visualization.
• Developed Electron-Beam Simulator (E-BeamSim) to model atomic movements and interactions under electron beam irradiation.
• Investigated nanopore formation in MXene Ti3C2Tx at room and elevated temperatures.

Main Results:

• At room temperature, electron beam irradiation caused random atomic displacement and titanium pileups at nanopore edges, validated by E-BeamSim.
• At elevated temperatures, surface functional groups were removed, and increased atomic mobility led to selective, layer-by-layer atom removal.
• Distinct temperature-dependent atomic transformations were observed during nanopore fabrication.

Conclusions:

• Automated STEM fabrication with real-time visualization enhances understanding of beam-induced transformations.
• Temperature plays a critical role in controlling nanopore formation mechanisms in 2D materials.
• This work facilitates defect engineering in functionalized MXene layers and other 2D materials for tailored membrane properties.