Atom hybridization of metallic elements: Emergence of subnano metallurgy for the post-nanotechnology

Miniaturizing metallic materials from the nanoscale to the atomic scale transforms the structures and physical properties. Among these sub-nanoscale materials, some catalysts exhibit activity superior to conventional nanoparticle catalysts. Furthermore, some subnanoparticles become superatoms that exhibit unusual physical properties that deviate from the properties of the original elements. However, conventional metallurgy and chemistry often do not apply to synthetic strategies, structural analysis, and functional design of materials because crystal structures disappear at the sub-nanoscale. This review focuses on the synthesis, structural analysis, and functionality at the sub-nanoscale, overviewing a series of materials research, so-called “atom hybridization,” in which atoms are hybridized to create desired materials for their applications.