An array of out-of-plane, nanowires may be formed spontaneously when a material is deposited over a freshly sputter-deposited porous film under high vacuum. The nanowires may be formed without an apparent catalyst. It is the nanoporous structure of the sputter-deposited porous film that confines the size of permeated material domains during its vapor deposition, which may cause a certain surface-to-volume ratio and subsequent melting point reduction, rendering the domains of the material molten or partially molten at room temperature. The release of surface energy provides a force for the domains to diffuse and to eventually erupt from the porous thin film and may form nanowires. Due to the universality of higher surface energy for nanoparticles, the present nanowires may be applicable for scalable growth of one-dimensional nanostructures of various other materials with moderate melting points. Furthermore, the absence of a catalyst in this method may eliminate the unwanted but inevitable diffusion of catalyst atoms into the nanostructures, thus allowing a route for the growth of nanostructure of higher purity and better controlled properties.
 The present application was made with government support under contract number DE-AC02-98CH 10886 and DE-SC0012704 awarded by the U.S. Department of Energy. The United States government has certain rights in the invention(s).