Atomic-scale friction of MoS2/Fe and MoO3/Fe interfaces: A first-principles investigation

Although it is a common phenomenon that MoS2 is oxidized during the service process, the role of its oxidation product MoO3 in the friction interface is rarely reported. Here, the adhesive work, sliding potential energy, and friction force of MoS2(001)/Fe(110) and MoO3(001)/Fe(110) interfaces were calculated via first-principles method. Furthermore, the relationship between charge density difference, potential barrier, and friction force was analyzed. The results show that the interfacial sliding potential barrier and friction force increased when MoS2 was oxidized to MoO3, but the adhesion with Fe substrate improved. The greater charge density difference may be responsible for the bigger friction force and adhesion between MoO3(001)/Fe(110) interface, which provides an explanation for the oxidation effect on tribological behaviors of MoS2 from an atomic-scale view.