Preparation of Flaky Hexagonal Nanoporous Au-Cu and Au Particles via Dealloying

Nanoporous metals have attracted significant attention owing to their excellent physical, chemical, and biological properties. However, preparing ultrafine nanoporous metal particles (1–5 μm) with specific geometries remains challenging. Herein, we report a simple strategy to prepare ultrafine flaky hexagonal nanoporous Au-Cu and Au particles via dealloying. Mg-based alloy ribbons with ultrafine flaky hexagonal Mg-Au(Cu)-Gd particles dispersed in a Mg-Cu(Au)-Gd metallic glassy matrix were prepared. The size and morphology of the precipitated flaky hexagonal Mg-Au(Cu)-Gd particles were controlled by the solidification process of a Mg61Cu21Au7Gd11 alloy melt. Ultrafine flaky hexagonal nanoporous Au-Cu particles (diagonal diameter 2.58 ± 0.44 μm, ligament size ~ 28 nm), Au-1 particles (diagonal diameter 2.38 ± 0.35 μm, ligament size ~ 83 nm) and Au-2 particles (diagonal diameter 2.39 ± 0.44 μm, ligament size ~ 66 nm) were prepared via ultrasonic-assisted dealloying of Mg61Cu21Au7Gd11 alloy ribbons in 0.25 M HCl/ethanol, 1 M HCl/ethanol and 0.25 M HNO3/ethanol solutions, respectively. The ultrafine flaky hexagonal nanoporous Au-Cu and Au particles with a large specific surface area have a uniform particle size and shape, implying that they possess adequate powder fluidity and excellent catalytic properties. Moreover, the formation mechanism of the MgAu(Cu)Gd phase in solidified Mg-Cu-Au-Gd alloys was discussed. This study provides a novel approach for synthesizing nanoporous metal particles with a specific geometry.