Constructing Denser Hydrogen-Bonding Networks in Polyoxometalate-Based Coordination Polymers for Enhancing Proton...

Area of Science:

• Materials Science
• Chemistry
• Solid-State Chemistry

Background:

• Designing crystalline proton-conductive materials is crucial for energy applications.
• Understanding proton conduction mechanisms in these materials is essential for performance optimization.

Purpose of the Study:

• To synthesize and characterize novel polyoxometalate-based coordination polymers for proton conduction.
• To investigate the relationship between material structure and proton conductivity.
• To identify effective strategies for enhancing proton conductivity in crystalline materials.

Main Methods:

• Hydrothermal synthesis of polyoxometalate-based coordination polymers (CUST-963 and CUST-964) using Keggin-type H4SiW12O40 (SiW12), H2DTA ligand, and transition metal ions.
• X-ray diffraction analysis to determine crystal structures and identify uncoordinated nitrogen sites.
• Alternating current impedance spectroscopy to measure proton conductivity and activation energy.

Main Results:

• CUST-963 possesses more uncoordinated nitrogen sites, facilitating a denser hydrogen-bonding network with SiW12 and water molecules.
• CUST-963 demonstrated superior proton conductivity (1.88 × 10^-2 S cm^-1) and lower activation energy (0.14 eV) compared to CUST-964 at 95 °C and 98% relative humidity.
• The structural features of CUST-963 directly correlate with its enhanced proton conduction capabilities.

Conclusions:

• The study successfully designed and synthesized two novel polyoxometalate-based coordination polymers.
• CUST-963's unique structural characteristics, particularly its hydrogen-bonding network, lead to high proton conductivity.
• This work presents an effective strategy for developing high-performance proton-conductive materials for potential applications.