Shape-controlled hydrogen evolution reaction of single Pd nanocrystals.

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Hydrogen evolution reaction (HER) is crucial for clean energy technologies.
• Understanding nanocatalyst structure-activity relationships is key to improving efficiency.
• Single-particle analysis offers unparalleled insight into catalytic mechanisms.

Purpose of the Study:

• To quantitatively investigate facet-dependent HER activity on palladium (Pd) nanocrystals.
• To establish a definitive structure-activity relationship at the single-entity level.
• To demonstrate a novel approach for probing intrinsic nanocatalyst activities.

Main Methods:

• Utilizing scanning electrochemical cell microscopy (SECCM) for single-particle analysis.
• Synthesizing Pd nanocrystals with controlled facets (octahedra and cubes).
• Quantitatively measuring the hydrogen evolution reaction kinetics on individual nanocrystals.

Main Results:

• Pd octahedra, exposing {111} facets, exhibited significantly higher intrinsic HER activity.
• Pd cubes, exposing {100} facets, showed lower HER activity.
• Clear correlation between facet type and catalytic performance was established.

Conclusions:

• The {111} facet of Pd is intrinsically more active for the hydrogen evolution reaction.
• Single-particle electrocatalysis studies are vital for understanding and optimizing nanocatalyst performance.
• This work provides a foundation for designing highly efficient Pd-based electrocatalysts.