Construct Ordered Proton Channels in Polyoxometalate-Based Metal-Organic Frameworks for Enhancing Proton Conduction

Area of Science:

• Materials Science
• Chemistry
• Solid-State Chemistry

Background:

• Proton conduction is crucial for energy applications.
• Ordered proton channels enhance proton conductivity.
• Polyoxometalate-based metal-organic frameworks (POMOFs) are promising materials.

Purpose of the Study:

• Synthesize novel POMOFs with ordered proton channels.
• Investigate the proton conductivity and stability of these materials.
• Understand the relationship between framework structure and proton transport.

Main Methods:

• Hydrothermal synthesis of POMOFs (CUST-973 and CUST-974).
• Thermogravimetric analysis (TGA) and powder X-ray diffraction (PXRD) for stability assessment.
• Alternating current (AC) impedance measurements for proton conductivity.
• Water vapor adsorption-desorption experiments for water uptake analysis.

Main Results:

• CUST-973 and CUST-974 exhibited excellent thermal and water stability.
• CUST-974 demonstrated a proton conductivity of 4.72 × 10⁻³ S cm⁻¹ at 90 °C and 98% relative humidity (RH), two orders of magnitude higher than CUST-973.
• CUST-974 possesses precisely aligned channels facilitating efficient proton transport via water molecules.
• CUST-974 showed higher water uptake capacity compared to CUST-973.

Conclusions:

• The ordered proton channels in CUST-974 are key to its superior proton conductivity.
• POMOFs with well-defined structures are effective for crystalline solid-state proton conductors.
• This research offers insights for designing advanced POMOFs for energy applications.