Bifunctional 3D POM-based coordination polymers for improved pseudocapacitance and catalytic oxidation performance.

Area of Science:

• Materials Science
• Inorganic Chemistry
• Electrochemistry

Background:

• Developing efficient energy storage devices like supercapacitors is crucial for addressing the energy crisis.
• Designing active and selective oxidation catalysts for sulfides remains a significant challenge in chemistry.

Purpose of the Study:

• To synthesize novel polyoxometalate-based coordination polymers (POMCPs) for dual applications in supercapacitors and catalysis.
• To investigate the structure-property relationships of these POMCPs based on varying synthesis conditions and metal centers.

Main Methods:

• A one-step hydrothermal or solvothermal synthetic strategy was employed to prepare three novel POMCPs: [{Ag6(pytz)4}{SiMo12O40}] (1), [{Cu3(pytz)4}{SiMo12O40}]·5.5H2O (2), and [{Cu6(pytz)6}{SiMo12O40}]·2H2O (3).
• The structural characteristics of the POMCPs were determined, revealing different coordination modes of the {SiMo12} polyoxoanions and metal-organic frameworks.
• Electrochemical performance was evaluated using supercapacitor testing, and catalytic activity was assessed for the selective oxidation of sulfides.

Main Results:

• The synthesized POMCPs exhibited excellent specific capacitances: 261.76 F g⁻¹ for compound 1, 248.82 F g⁻¹ for compound 2, and 156.47 F g⁻¹ for compound 3 at 0.5 A g⁻¹.
• Compounds 1 and 2 feature 2D Ag/Cu-organic sheets incorporating 9-capped and 2-capped {SiMo12} polyoxoanions, forming 3D POMCPs.
• Compound 3 consists of 1D Cu-organic chains combined with 3-capped {SiMo12} polyoxoanions, forming 2D POMCPs.
• All three compounds demonstrated effective and selective catalytic activity in oxidizing various sulfides to sulfoxides.

Conclusions:

• The novel POMCPs show promising potential as electrode materials for high-performance supercapacitors.
• These POMCPs also function as effective catalysts for the selective oxidation of sulfides, highlighting their versatility.
• The study demonstrates a successful approach to designing multifunctional materials by integrating polyoxometalates with metal-organic frameworks.