Facile fabrication of ultrasmall and uniform copper nanoparticles

► Ultrasmall and uniform copper nanoparticle was synthesized through a trace-level EDTA-assisted wet chemical route. ► Copper nanoparticle has a narrow size distribution, a uniform shape, and the average diameter of ca. 4 nm. ► EDTA concentration directly influences the copper nanoparticle size and uniformity.