Two Unprecedented Germanoniobate Frameworks Based on High-Nuclearity Peanut-Shaped {Ge₁₂Nb₃₈} Clusters

Area of Science:

• Materials Science
• Inorganic Chemistry
• Nanotechnology

Background:

• Germanoniobates are advanced inorganic-organic hybrid materials with potential applications in catalysis and energy storage.
• Constructing novel frameworks with specific topologies and functionalities remains a key challenge in materials chemistry.

Purpose of the Study:

• To synthesize novel germanoniobate frameworks with diverse topologies by varying germanium dioxide (GeO2) content.
• To investigate the proton conduction properties and water vapor adsorption capacities of the newly synthesized materials.

Main Methods:

• Utilized solvothermal synthesis to construct germanoniobate frameworks from peanut-shaped {α-Ge12Nb38} and {β-Ge12Nb38} clusters.
• Characterized the crystal structures and determined the proton conductivity and water vapor adsorption capacities of the resulting compounds.

Main Results:

• Successfully synthesized two organic-inorganic hybrid germanoniobate frameworks with 6-connected pcu and 10-connected bct topologies.
• The {α-Ge12Nb38} and {β-Ge12Nb38} clusters represent the highest Ge content reported for germanoniobates.
• Achieved proton conductivities of 3.04 × 10^-4 S·cm^-3 for compound 1 and 1.62 × 10^-4 S·cm^-3 for compound 2 at 85 °C and 98% relative humidity.
• Observed water vapor adsorption capacities of 5.86 mmol·g^-1 for compound 1 and 4.40 mmol·g^-1 for compound 2.

Conclusions:

• The variation in GeO2 amount enables the construction of germanoniobate frameworks with distinct topologies and properties.
• The synthesized germanoniobates exhibit promising proton conductivity and water vapor adsorption, indicating potential for applications in proton exchange membranes and gas storage.