Effects of moiré lattice distortion and π bond on the superlubricity of twist MoS₂/graphene and MoS₂/BN heterointerfaces

Superlubricity, a novel lubricity mode ascribing to moiré superlattice (MSL), has attracted attention in ultra-precise manufacture, microelectronic devices, and national defense areas. Based on incommensurate MSL, nearly zero friction can be achieved by eliminating sliding lock-in and offsetting lateral force in principle, and the theoretical foundations are still under extensive investigation. Here, the effects of MSL-induced lattice distortion on π bond and tribological performance in twist MoS₂/graphene and MoS₂/BN heterointerfaces were studied by first-principles calculations comprehensively. Various contributions of 2p_z orbital electron polarization among AA-, AB-, and AC-stacking symmetry areas in different MSL were reflected by band structures to explain the sensitivity of π bond to MSL. The π bond perpendicular to the atomic plane depended closely on interfacial distortion, which can not only influence the local distribution of intralayer bond strength but also determine the interlayer charge redistribution. Meanwhile, the interfacial potential energy was changed with the interlayer interaction fluctuation caused by twist angle and atomic stacking modes. Through evaluating the energy barriers and lateral force, MoS₂/BN with a twist angle of 20.79° exhibited superlubricity. Moreover, the connection among sliding energy barriers, twist angles, and specific electronic structures has been bridged paving a path to reveal the superlubricity mechanism of two-dimensional materials with π bond.