Sandwich-Structured Covalent Organic Framework as a Proton Exchange Membrane

Area of Science:

• Materials Science
• Electrochemistry
• Chemical Engineering

Background:

• Developing proton exchange membranes (PEMs) for fuel cells that perform well at high temperatures and low humidity is crucial.
• Current PEMs often suffer from decreased proton conductivity and stability under these demanding conditions.

Purpose of the Study:

• To synthesize and characterize a novel sandwich-type layered covalent organic framework (COF) membrane, termed BD/SB/BD, for improved fuel cell performance.
• To evaluate the proton conductivity and stability of the BD/SB/BD membrane, particularly under elevated temperatures and reduced humidity.

Main Methods:

• Synthesis of a composite membrane with a TpSB-(SO3H)2 layer sandwiched between TpBD-(SO3H)2 layers.
• Characterization of the membrane's structure and properties.
• Measurement of proton conductivity at various temperatures and humidity levels.

Main Results:

• The BD/SB/BD composite membrane achieved high proton conductivity (158 mS cm⁻¹ at 90°C, 100% RH).
• The composite membrane demonstrated superior performance compared to single-component membranes under intermediate-to-low humidity at 100°C.
• Enhanced water retention and dimensional stability were observed due to the synergistic effect of the COF components.

Conclusions:

• The BD/SB/BD membrane offers a promising solution for high-temperature, low-humidity fuel cell applications.
• The unique layered structure and combination of COF components contribute to improved proton conductivity and membrane stability.
• This work advances the development of next-generation proton exchange membranes for efficient energy conversion.