Fabrication of ultrafine nanoporous copper by the minor addition of gold

Ultrafine nanoporous Cu was successfully fabricated through the dealloying of amorphous Ti ₆₀Cu _40-xAu _x (x = 0, 1, 2 at%) ribbon alloys in 0.65M HF solution under free immersion conditions. A bicontinuous nanoporous structure of Cu formed on Ti ₆₀Cu ₄₀, Ti ₆₀Cu ₃₉Au ₁ and Ti ₆₀Cu ₃₈Au ₂ ribbons with pore sizes of 134, 8.9 and 7.4 nm, respectively. The pore size of the nanoporous Cu dealloyed from Au-added alloys was more than one order smaller than that of the TiCu alloy, which resulted from the 5-order decrease in the surface diffusivity through alloying of Au into Ti ₆₀Cu ₄₀ ribbons. The Au content increased rapidly during the dealloying process and eventually formed binary CuAu solid solution and Au nanoparticles. Modifying the surface diffusivity by adding Au made it possible for the formation of the ultrafine nanoporous Cu structure.