Ultrahigh Proton Conduction in Two Highly Stable Ferrocenyl Carboxylate Frameworks

Area of Science:

• Materials Science
• Electrochemistry
• Solid-state Chemistry

Background:

• Research in proton conductive materials has expanded beyond sulfonated polymers to crystalline solids like MOFs, COFs, and HOFs.
• Crystalline ferrocene-based carboxylate materials remain under-explored despite their potential.

Purpose of the Study:

• To investigate water-mediated proton conduction in two novel ferrocenyl carboxylate frameworks (FCFs).
• To evaluate the stability and performance of these FCFs for potential electrochemical applications.

Main Methods:

• Synthesis and characterization of two ferrocenyl carboxylate frameworks (FCFs) using hydrogen-bonded and π-π interactions.
• Assessment of thermal, water, and chemical stability via thermogravimetric analyses, PXRD, and SEM.
• Measurement of temperature- and humidity-dependent proton conductivity.

Main Results:

• FCFs 1 and 2 demonstrated excellent thermal, water, and chemical stability.
• Ultrahigh proton conductivities of 1.17 × 10⁻¹ S/cm (FCF 1) and 1.01 × 10⁻² S/cm (FCF 2) were achieved at 100 °C and 98% RH.
• Performance comparable to commercial Nafion membranes and among the highest reported for MOFs, HOFs, and COFs.

Conclusions:

• The FCFs exhibit outstanding proton conducting properties, driven by water-mediated mechanisms.
• These materials represent a novel class of high-performance proton conductors with significant potential for fuel cells and electrochemical devices.