Low temperature preparation of hollow carbon nano-polyhedrons with uniform size, high yield and graphitization

► Hollow carbon nano-polyhedrons (HCNPHs) were prepared on large-scale at 250 °C ► The HCNPHs with uniform size exhibit a high degree of graphitization. ► The graphitization results in the contraction of carbon shell around Ni nanoparticle. ► Ni nanoparticle changing into polyhedron causes stress concentration at apexes. ► Squeezing Ni polyhedron out of carbon shell results in the creation of HCNPHs.