Oxidative etching and regrowth route to icosahedral gold nanocrystals with strain-enhanced electrocatalytic properties

Icosahedral metal nanocrystals, with their inherent strain, offer exceptional catalytic properties. However, synthesizing these nanocrystals with high morphological yield remains a significant challenge, limiting the potential of strain engineering for catalyst design. In this study, we introduce a robust oxidative etching and regrowth strategy to synthesize high-yield (~ 90%) icosahedral Au nanocrystals with tunable sizes (12–43 nm). By employing triiodide (I₃⁻) as an oxidative agent, we selectively enrich multiply twinned seeds—the required seed type for icosahedral formation—by removing impurity seeds. Additionally, sulfite ions (SO₃²⁻) selectively cap the Au {111} facet, directing crystal growth toward the desired icosahedral shape. The resulting Au nanocrystals demonstrate strain-enhanced electrocatalytic performance in CO₂ reduction, achieving a Faradaic efficiency of 97.5% for CO production, significantly higher than their non-strained counterparts. This strategy offers a promising pathway for creating well-defined metal nanocrystals, opening new possibilities for both fundamental catalysis research and practical applications.