Surface structure and electrochemical signatures of copper nanocrystals with tunable facets

Understanding the surface structure of copper nanocrystals is critical for optimizing their catalytic performance in electrochemical reactions such as CO2 reduction, hydrogen evolution, and nitrate reduction. Copper nanowires (CuNWs) and nanoplates (CuNPls) exhibit distinct morphologies and facet distributions influenced by halide ion concentration during synthesis. Here we systematically modulated Br- and I- concentrations to direct the growth of CuNWs and CuNPls, characterized their structures via XRD, SEM, and TEM, and probed their surface facets using cyclic voltammetry and Pb underpotential deposition. CuNWs predominantly expose (100) facets with higher surface roughness, while CuNPls are dominated by (111) facets with smoother surfaces, each displaying unique electrochemical fingerprints. These insights into facet-controlled synthesis and surface characterization provide a foundation for rational design of copper-based electrocatalysts tailored for sustainable energy applications.