MOF-Based Solid-State Proton Conductors Obtained by Intertwining Protic Ionic Liquid Polymers with MIL-101

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Metal-organic frameworks (MOFs) are explored for proton exchange membranes.
• Current proton conductors face limitations in performance and stability.
• Developing advanced solid-state proton conductors is crucial for energy technologies.

Purpose of the Study:

• To synthesize and characterize novel proton conductors based on MIL-101 and protic ionic liquid polymers (PILPs).
• To investigate the proton transport properties and mechanism in the new composite materials.
• To evaluate the potential of these materials as alternatives to existing proton exchange membranes.

Main Methods:

• In situ polymerization of protic ionic liquid (PIL) monomers within the MIL-101 MOF structure.
• Synthesis of PILP@MIL-101 composites with varying anions.
• Characterization of proton conductivity using electrochemical impedance spectroscopy.
• Structural analysis of PIL monomers via single crystal X-ray diffraction.

Main Results:

• PILP@MIL-101 composites retained the structural integrity and water stability of MIL-101.
• The composite with HSO4- anions demonstrated superprotonic conductivity of 6.3 × 10^-2 S cm^-1 at 85°C and 98% relative humidity.
• Strong hydrogen bonding interactions within PIL monomers were observed, facilitating proton transport.

Conclusions:

• PILP@MIL-101 composites represent a new class of highly efficient solid-state proton conductors.
• The enhanced proton transport is attributed to the intertwined PILPs within the MOF structure.
• These materials show significant promise for applications in fuel cells and other electrochemical devices.