Systems and methods for fabricating nanostructures using other nanostructures as templates. A method includes mixing a dispersion and a reagent solution. The dispersion includes nanostructures such as nanowires including a first element such as copper. The reagent solution includes a second element such as silver. The second element at least partially replaces the first element in the nanostructures. The nanostructures are optionally washed, filtered, and/or deoxidized.