Theoretical study on the electronic properties and stabilities of low-index surfaces of WC polymorphs

► This paper investigates the low-index surfaces of WC polymorphs by using DFT. ► The electronic structures, chemical stabilities and thermodynamic properties are studied. ► There are large relaxations within the top three layers for all termination surfaces, and charge density falls greatly toward the vacuum. ► The surface energies for all low-index surfaces are large, which indicate the reactive features. ► The most stable surfaces correspond to the (0 0 1) surface with W termination for α-WC, and the (0 0 1) non-polar surface for β-WC.