A new application area using a very simple alkali metal chalcogenide, disodium diselenide (Na₂Se₂), has been developed. The prepared alkali metal chalcogenide (disodium diselenide, Na₂Se₂) acts as an anionic exchange precursor (PbS to PbS–PbSe), a Se precursor for metal selenide nanoparticles (Ag to Ag₂Se), and a MCC (FeO–MCC) depending on the type of colloidal nanoparticles.