Proton Conducting Membranes with Molecular Self Assemblies and Ionic Channels for Efficient Proton Conduction

Area of Science:

• Materials Science
• Electrochemistry
• Supramolecular Chemistry

Background:

• Supramolecular assemblies are crucial in biological systems and influence artificial material properties.
• Efficient proton conduction, especially in anhydrous conditions, is a significant challenge for fuel cell technologies.

Purpose of the Study:

• To fabricate highly efficient proton conducting molecular wires for fuel cell applications using a simple supramolecular assembly approach.
• To investigate proton conduction in molecular assemblies under anhydrous conditions.

Main Methods:

• Fabrication of small molecule-based molecular assemblies with a discotic columnar architecture.
• Incorporation of high boiling point proton facilitators into central ionic channels of the columns.
• Evaluation of proton conductivity in the anhydrous state.

Main Results:

• Achieved discotic columnar supramolecular assemblies capable of efficient proton conduction without water.
• Demonstrated that high boiling point proton facilitators significantly increased conduction.
• Observed a highest conductivity approaching 10^-2 S/cm in the anhydrous state due to a continuous hydrogen bond network.
• Found that larger and asymmetrical facilitators disrupted self-assembly and reduced efficiency.

Conclusions:

• The developed molecular wires exhibit high proton conductivity under anhydrous conditions, offering a potential alternative to conventional proton conductors.
• The self-assembled structures with ionic channels are promising for fuel cell applications operating at both low and high temperatures without water.
• The design principle highlights the importance of facilitator size and symmetry for efficient supramolecular assembly and proton transport.