Accelerating Hydrogen Absorption and Desorption Rates in Palladium Nanocubes with an Ultrathin Surface Modification

Area of Science:

• Materials Science
• Nanotechnology
• Electrochemistry

Background:

• Nanomaterials offer high surface-area-to-volume ratios for energy storage via electrochemical alloys.
• Nanoscale palladium hydride (PdHₓ) is a model system for studying nanoscale effects on energy storage.
• Hydrogen absorption/desorption in Pd nanostructures is limited to high-activity sites (corners/edges), hindering rates.

Purpose of the Study:

• To investigate methods for improving hydrogen absorption and desorption rates in palladium nanostructures.
• To understand how surface modification affects nanoscale energy storage mechanisms.
• To overcome limitations imposed by selective surface activity in palladium nanoparticles.

Main Methods:

• Fabrication of shape-controlled palladium (Pd) nanostructures.
• Surface modification of Pd nanostructures with an ultrathin platinum (Pt) shell.
• Measurement of hydrogen absorption/desorption kinetics and energy barriers.

Main Results:

• Hydrogen absorption/desorption in unmodified Pd nanostructures occurs non-uniformly at corners and edges.
• Platinum shell modification significantly reduced the hydrogen absorption barrier from 89 kJ/mol to 1.8 kJ/mol.
• The Pt shell enabled uniform hydrogen diffusion across the entire Pd/Pt nanoparticle surface.

Conclusions:

• Surface modification with platinum is a viable strategy to enhance hydrogen storage kinetics in palladium nanostructures.
• Overcoming selective surface activity through Pt coating unlocks the full potential of nanoscaled palladium for high-rate energy storage.
• This approach paves the way for more efficient electrochemical energy storage systems utilizing nanomaterials.