Self-Standing Pd-Based Nanostructures for Electrocatalytic CO Oxidation: Do Nanocatalyst Shape and Electrolyte pH...

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Tailoring palladium (Pd) nanocrystal shape is crucial for catalytic activity.
• The influence of morphology and electrolyte pH on carbon monoxide oxidation (CO$_{Oxid}$) requires further investigation.

Purpose of the Study:

• To controllably synthesize Pd nanocrystals with distinct morphologies (nanosponge and nanocube).
• To evaluate the electrocatalytic CO$_{Oxid}$ activity and durability of these Pd nanocrystals across different electrolyte pHs.
• To elucidate the structure-property relationships governing CO$_{Oxid}$ performance.

Main Methods:

• Controlled synthesis of Pd nanosponge via ice-cooling reduction with NaBH$_{4}$.
• Controlled synthesis of Pd nanocube via ascorbic acid reduction at 25 °C.
• Electrochemical characterization including CO$_{Oxid}$ activity and electrochemical impedance spectroscopy (EIS) in acidic, neutral, and alkaline media.

Main Results:

• Pd nanocubes exhibited superior CO$_{Oxid}$ activity and durability in acidic media (H$_{2}$SO$_{4}$) compared to Pd nanosponge and commercial Pd/C.
• Pd nanosponge demonstrated enhanced CO$_{Oxid}$ activity and stability in alkaline (KOH) and neutral (NaHCO$_{3}$) electrolytes.
• Both Pd nanosponge and Pd nanocube showed higher activity than Pd/C in all tested electrolytes.
• CO$_{Oxid}$ current density for Pd nanocube was highest in acidic conditions, attributed to better charge mobility and electrolyte-electrode interaction.

Conclusions:

• Pd nanocrystal shape and electrolyte pH are critical factors for optimizing CO$_{Oxid}$ electrocatalysis.
• Pd nanocubes are highly effective in acidic electrolytes for CO$_{Oxid}$.
• Pd nanosponges show promise in neutral and alkaline environments.
• Findings suggest acidic electrolytes and Pd nanocubes are preferred for promoting CO$_{Oxid}$ and mitigating CO poisoning in alcohol-based fuel cells.