Correlating interfacial binding strength with the nanofriction and wear behavior of monolayer MoSe2

The rapid development of micro/nano-electromechanical systems (M/NEMS) under extreme contact conditions require atomic-scale lubricants with ultrathin thickness (<1 nm), ultralow friction (coefficient of friction<0.01), and high wear resistance. Two-dimensional (2D) transition metal dichalcogenides (TMDs), such as MoSe 2 , are promising candidates. However, the role of substrates in governing the friction and wear behavior of monolayer TMDs remains unclear. Here, high-quality monolayer MoSe 2 films with a thickness of ~0.7 nm were synthesized by chemical vapor deposition on five representative substrates, including SiO 2 /Si, Si, quartz, a-plane sapphire, and c-plane sapphire. The study systematically investigated the role of interfacial bonding strength in regulating tribological properties. Significantly, MoSe 2 on quartz exhibited ultralow friction (COF=0.009) and exceptional wear resistance (40,000 cycles@3.02 GPa), significantly outperforming other substrates. Conversely, MoSe 2 on Al 2 O 3 showed inferior performance (COF=0.015; <5,000 cycles@3.02 GPa), which is attributed to a MoO 3 -related interfacial layer that reduces bonding strength. Density functional theory (DFT) simulations revealed a positive correlation between tribological performance and interfacial interaction strength. Stronger interfacial interactions provide enhanced anchoring of the monolayer, which can suppress out-of-plane deformation and delamination, thereby reducing energy dissipation. This work identifies interfacial bonding strength as the key factor governing ultrathin 2D material tribology, providing essential guidelines for designing durable, low-friction lubrication systems for future M/NEMS.