Preyssler-Type POM-Based CPs Incorporating V-Type N-Heterocyclic Ligands as Proton Conductors

Area of Science:

• Materials Science
• Inorganic Chemistry
• Nanotechnology

Background:

• Polyoxometalate-based coordination polymers (POM-based CPs) are attractive proton-conducting materials.
• Preyssler anions, with their oxygen-rich surfaces, offer unique structural and functional advantages for proton conduction.
• Developing efficient proton conductors is crucial for energy applications like fuel cells.

Purpose of the Study:

• To synthesize and characterize novel POM-based CPs incorporating Preyssler anions and a V-type N-heterocyclic ligand (btp).
• To investigate the proton conductivity of these new materials.
• To evaluate the potential of these CPs in composite membranes for enhanced proton conduction.

Main Methods:

• Synthesis of three coordination polymers: {[Zn4(H2O)8(H7P5W30O110)(btp)4]·6H2O}n (1), {[Ni4(H2O)8(H7P5W30O110)(btp)4]·14H2O}n (2), and {[Cd5(μ2-H2O)(H2O)14(H5P5W30O110)(btp)4]·8H2O}n (3).
• Structural analysis of the synthesized compounds to determine their framework architectures (2D layers and 3D framework).
• Proton conductivity measurements under varying humidity and temperature conditions, and in composite membranes with Nafion.

Main Results:

• Compounds 1 and 2 form 2D layer structures with sql topology, while compound 3 exhibits a 3D framework.
• The synthesized POM-based CPs demonstrate good intrinsic proton conductivity, reaching up to 2.92 × 10⁻³ S cm⁻¹ at 85 °C and 98% RH.
• Incorporation into Nafion composite membranes significantly enhances proton conductivity to 10⁻² S cm⁻¹ under the same conditions.

Conclusions:

• The synthesized Preyssler-type POM-based CPs exhibit promising proton conductivity.
• The structural diversity (2D vs. 3D) influences material properties.
• Composite membranes with Nafion show significantly improved proton conductivity, highlighting their potential for advanced energy applications.