Direct Visualization and Quantitative Insights into the Formation and Phase Evolution of Cu Nanoparticles via In Situ...

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Copper (Cu)-based nanomaterials are efficient heterogeneous electrocatalysts for CO2 reduction.
• Catalyst selectivity and stability depend heavily on morphology, crystal structure, and composition.
• Understanding dynamic evolution is crucial for optimizing Cu-based electrocatalysts and structure-property relationships.

Purpose of the Study:

• To demonstrate the integration of in situ liquid phase transmission electron microscopy (LP-TEM) with 4D scanning transmission electron microscopy (4D-STEM).
• To reveal the dynamic morphology and phase evolution of Cu nanoparticles during electrodeposition and electrooxidation in liquid.
• To gain quantitative insights into the evolution of defective nanocrystalline Cu nanoparticles.

Main Methods:

• In situ liquid phase transmission electron microscopy (LP-TEM).
• 4D scanning transmission electron microscopy (4D-STEM).
• Virtual imaging and selected area electron diffraction.
• Virtual off-axis dark field imaging.

Main Results:

• Dynamic morphology and phase evolution of Cu nanoparticles were observed in liquid during electrodeposition and electrooxidation.
• Novel insights into the evolution of defective nanocrystalline Cu nanoparticles were provided.
• Virtual off-axis dark field imaging successfully mapped the distribution of Cu2O and Cu in partially oxidized Cu nanoparticles.

Conclusions:

• The integration of LP-TEM and 4D-STEM enables quantitative probing of electrocatalysts under operando conditions.
• This approach offers new opportunities for understanding and developing advanced Cu-based electrocatalysts.
• Detailed insights into nanoparticle evolution facilitate the design of highly selective and stable catalysts for CO2 reduction.