Pd-incorporated polyoxometalate catalysts for electrochemical CO₂ reduction

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Polyoxometalates (POMs) are anionic metal-oxo clusters with tunable properties.
• POMs are promising candidates for electrochemical carbon dioxide reduction reaction (CO₂RR) catalysts.
• Countercations significantly influence POM properties and catalytic performance.

Purpose of the Study:

• To synthesize and evaluate POM-based catalysts with various countercations (TBA+, Cs+, Sr2+, Ba2+) for CO₂RR.
• To investigate the effect of countercations on the selectivity and stability of dipalladium-incorporated POMs (Pd2/C).
• To understand the structural transformations of POM catalysts during CO₂RR.

Main Methods:

• Synthesis of tetra-n-butylammonium (TBA+), Cs+, Sr2+, and Ba2+ salts of dipalladium-incorporated POM (Pd2).
• Immobilization of Pd2 on a carbon support (Pd2/C).
• Electrochemical evaluation of CO₂RR using gas-diffusion flow electrolysis cells.

Main Results:

• BaPd2/C exhibited high selectivity (>90%) towards carbon monoxide (CO) production.
• TBAPd2/C showed moderate selectivity for CO (approx. 40%) and hydrogen (approx. 60%).
• BaPd2/C maintained high CO selectivity over 12 hours, unlike palladium acetate precursor.

Conclusions:

• Countercations play a crucial role in modulating the CO₂RR performance of POM-based electrocatalysts.
• BaPd2/C demonstrates excellent selectivity and stability for CO production.
• POMs offer a versatile platform for designing efficient electrocatalysts for CO₂ conversion.