Achieving Superprotonic Conduction with a 2D Fluorinated Metal-Organic Framework.

Area of Science:

• Materials Science
• Electrochemistry
• Physical Chemistry

Background:

• Protonic conduction is crucial for energy applications like fuel cells.
• Current proton-exchange membranes, such as Nafion, face limitations in performance and stability.
• Metal-organic frameworks (MOFs) offer tunable properties for advanced material applications.

Purpose of the Study:

• To investigate the proton conductivity and stability of a novel MOF material, KAUST-7'.
• To explore the potential of KAUST-7' as a proton-exchange membrane and humidity sensor.
• To elucidate the mechanism of proton transport in KAUST-7'.

Main Methods:

• Synthesis of KAUST-7' via structural phase change of KAUST-7.
• Impedance spectroscopy to measure proton conductivity under varying conditions (363 K, 95% RH).
• Ab initio molecular dynamics simulations to study proton transport mechanisms.

Main Results:

• KAUST-7' demonstrated superprotonic conductivity of up to 2.0 × 10^-2 S cm^-1 at 363 K and 95% RH, stable for 7 days.
• Water-mediated proton transport mechanism involving fluorine moieties and guest water molecules was identified.
• KAUST-7' exhibited remarkable relative humidity (RH) sensitivity.

Conclusions:

• KAUST-7' is a hydrolytically stable MOF with high proton conductivity, positioning it as a potential alternative to Nafion.
• The material's significant RH sensitivity opens avenues for its use in humidity sensing applications.
• The findings highlight the potential of MOFs in developing next-generation proton-exchange materials.