A facile one-pot route to fabricate nanoporous copper with controlled hierarchical pore size distributions through chemical dealloying of Al–Cu alloy in an alkaline solution

We present a facile and effective one-pot strategy to synthesize nanoporous copper (NPC) with controlled hierarchical pore size distributions which can be fabricated through chemical dealloying of the melt-spun Al-35Cu alloy in a 10 wt.% sodium hydroxide (NaOH) solution at an elevated temperature. These NPC ribbons are composed of large-sized ligament–pore structures (several hundred nanometers) at outer layers coupled with small-sized those (several ten nanometers) at inner layers. Both large- and small-sized pores are 3D, open and bicontinuous. The formation of the novel NPC ribbons can be well explained based upon the synergetic action between diffusion mechanism and pore size effect. According to the ligament sizes, the surface diffusivities at inner and outer layers of Cu adatoms can be evaluated as 3.80 × 10−20, 1.63 × 10−18, 3.54 × 10−18, 6.83 × 10−18 and 7.88 × 10−20, 5.41 × 10−17, 4.36 × 10−16, 4.27 × 10−15 m2 s−1 for the dealloying at 298, 333, 348 and 363 K, respectively. The activation energies and diffusion constants at inner and outer layers are also measured as 47.7 kJ mol−1, 1.41 × 10−17 m2 s−1 and 145.3 kJ mol−1, 4.21 × 10−14 m2 s−1, suggesting the existence of a complicated dealloying mechanism. Additionally, the length scales of ligaments/pores at inner and outer layers can be modulated by simply changing the dealloying temperature or duration at a fixed elevated temperature.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights►We present a one-pot route to fabricate NPC with controlled hierarchical pore size distributions. ►The length scales of ligaments/pores at inner and outer layers of NPC can be easily modulated. ►The surface diffusivities and activation energies at inner and outer layers can be evaluated. ►Some lattice defects during dealloying at an elevated temperature can be formed. ►Superfine single-crystal nanoparticles on the ligament surfaces of NPC can be obtained by dealloying at 90 °C.