Identical Grain Atomic Force Microscopy Elucidates Facet-Dependent Restructuring of Copper for CO₂ Electroreduction

Area of Science:

• Materials Science
• Electrochemistry
• Surface Science

Background:

• Electrochemical CO2 reduction (eCO2RR) catalyst restructuring is understudied, with limited focus on Cu single crystals.
• A comprehensive understanding of dynamic restructuring across different Cu facets is lacking.

Purpose of the Study:

• To investigate facet-dependent restructuring of polycrystalline copper electrodes during eCO2RR.
• To reveal the influence of crystal facet asymmetry on surface evolution and restructuring behavior.

Main Methods:

• Utilized electron backscatter diffraction (EBSD) to analyze crystal domain evolution.
• Employed identical grain atomic force microscopy (AFM) to map surface topography changes.
• Applied statistic slope distribution function to quantify restructuring asymmetry.

Main Results:

• Cu (001) facets restructured into square morphologies with 4-fold asymmetry.
• Cu (111) facets showed triangular features with 3-fold asymmetry.
• Stepped facets (Cu (114), (212), (124)) displayed 2-fold asymmetry, forming elongated structures.

Conclusions:

• Surface restructuring during eCO2RR is dictated by the inherent lattice asymmetry of copper facets (planar vs. atom-stepped).
• Combining EBSD and AFM provides multi-scale insights into catalyst restructuring mechanisms.