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.
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