Deciphering Site-Specific Kinetics on Shaped Pd Nanocrystals via Single-Particle Electrocatalysis.

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Catalytic activity and selectivity are heavily influenced by particle size and surface site characteristics.
• Directly measuring the electrocatalytic activity of specific surface sites at the atomic level is experimentally difficult.

Purpose of the Study:

• To precisely analyze the intrinsic electrocatalytic activities of specific surface atoms (edge vs. plane) on individual palladium nanocubes.
• To utilize a correlated scanning electrochemical cell microscopy-transmission electron microscopy (SECCM-TEM) approach for site-specific analysis.

Main Methods:

• Correlated scanning electrochemical cell microscopy-transmission electron microscopy (SECCM-TEM) was used on individual palladium nanocubes (down to 8 nm).
• The hydrogen evolution reaction (HER) served as the model electrocatalytic process.
• Density functional theory (DFT) calculations and studies on Pd-Au nanocubes were performed for validation.

Main Results:

• Edge sites on palladium nanocubes demonstrated a HER turnover frequency approximately four times higher than that of (100) plane sites.
• SECCM-TEM provided unambiguous insights into the distinct catalytic properties of edge and plane sites.
• DFT calculations and Pd-Au nanocube studies corroborated the crucial role of edge atoms in catalysis.

Conclusions:

• Specific surface atomic arrangements, particularly edge sites, play a pivotal role in electrocatalysis.
• The developed SECCM-TEM methodology offers a powerful tool for deciphering active sites in complex electrocatalysts.
• Understanding site-specific activity is crucial for designing more efficient and selective electrocatalysts.