Refinement of Nanoporous Copper: A Summary of Micro-Alloying of Au-Group and Pt-Group Elements

Abstract

The micro-alloying of 1 at% metals of Au-Group (Ag, Au) and the Pt-Group (Ni, Pd, Pt) with the Ti₆₀Cu₄₀ amorphous alloy resulted in the formation of fine nanoporous copper (NPC) in the order of 6–28 nm. The smallest characteristic pore size of open–cell nanoporous fcc Cu was 7 and 6 nm after dealloying the amorphous Ti₆₀Cu₃₉Pd₁ and Ti₆₀Cu₃₉Pt₁ precursor alloys for 43.2 ks in 0.03 M HF solution, while NPC had a pore size of 39 nm after dealloying the amorphous Ti₆₀Cu₄₀ precursor alloy. On the basis of TEM micrographs, the refining factor increased approximately from 4 for the Ti₆₀Cu₃₉Ag₁ precursor alloy to 1780 for the Ti₆₀Cu₃₉Pt₁ precursor alloy. The refinement was attributed to the dramatic decrease in the surface diffusivity during dealloying. The refinement efficiency of the micro-alloying of the Pt-group elements was higher than that of the Au-group elements. The homogeneous distribution of additives in both of the amorphous precursor alloys and the final stabilized NPCs played a key role in refining the NPCs. This strategy may contribute to the fabrication of cost-effective nanoporous metals with a nanoporosity comparable to that of nanoporous Au, Pd and Pt catalysts.