Uniaxially Oriented Electrically Conductive Metal-Organic Framework Nanosheets Assembled at Air/Liquid Interfaces

Area of Science:

• Materials Science
• Nanotechnology
• Electrochemistry

Background:

• Most metal-organic frameworks (MOFs) are electrically insulating, limiting their use in electronic devices.
• Electronically active MOFs are crucial for applications like sensors and supercapacitors, but require thin-film fabrication.
• Controlling thin-film morphology is essential for device performance but remains challenging.

Purpose of the Study:

• To develop a bottom-up synthesis for conductive MOF thin films with controlled morphology.
• To create a highly crystalline and uniaxially oriented MOF nanosheet.
• To achieve high electrical conductivity in a thin MOF film for electronic applications.

Main Methods:

• Air/liquid (A/L) interfacial bottom-up synthesis was employed to create MOF nanosheets.
• Synchrotron X-ray crystallography was used to characterize the crystallinity and orientation of the MOF.
• Electrical conductivity measurements were performed on the transferred MOF nanosheets.

Main Results:

• A conductive MOF nanosheet (HITP-Ni-NS) composed of hexaiminotriphenylene and nickel ions was successfully synthesized.
• The HITP-Ni-NS exhibited a multilayered structure with 14 nm thickness, high crystallinity, and uniaxial orientation.
• The material achieved an electrical conductivity of 0.6 S cm⁻¹, the highest reported for triphenylene-based MOF nanosheets under 100 nm thickness.

Conclusions:

• The A/L interfacial synthesis provides precise control over MOF thin-film morphology.
• HITP-Ni-NS demonstrates exceptional electrical conductivity and structural order, suitable for electronic devices.
• This work paves the way for utilizing conductive MOFs in various high-performance electronic applications.