Phase diagrams of graphene-metal systems

Abstract

Abstract Graphene-metal composites have attracted tremendous interests due to their promising applications in electronics, optics, energy-storage devices and nano-electromechanical systems. However, seldomly have the phase diagrams of graphene-metal systems been depicted since graphene was first extracted from graphite in 2004. Here, we utilized ab initiocalculations and the CALPHAD (Calculation of Phase Diagrams) approach to obtain the graphene-metal phase diagrams. A total of thirty-four binary systems have been calculated in the present work, in which the existence or shapes of intermediate phases show significant differences. Accordingly, the phase diagrams of graphene-transition metal systems have been divided into three major types: no compound formed (Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, Ag, Re, Pt, and Au), linear compounds formed (Cr, Mn, Mo, and W), or secondary solid solutions formed (Ti, V, Y, Zr, Nb, Hf, and Ta). Thus, we propose a general formation rule for intermediate phase by analyzing the calculated the phase diagrams and formation enthalpy of carbides, indicating that elements with smaller ordinal numbers in the same period are more likely to form secondary solutions with graphene.