Nano-friction behavior of phosphorene

Abstract

Nano-friction of phosphorene plays a significant role in affecting the controllability and efficiency of applying strain engineering to tune its properties. So far, the friction behavior of phosphorene has not been studied. This work studies the friction of single-layer and bilayer phosphorene on an amorphous silicon substrate by sliding a rigid tip. For the single-layer phosphorene, it is found that its friction is highly anisotropic, i.e. the friction is larger along the armchair direction than that along the zigzag direction. Moreover, pre-strain of the phosphorene also exhibits anisotropic effects. The friction increases with the pre-strain along the zigzag direction, but decreases with that along the armchair direction. Furthermore, the strong adhesion between the phosphorene and its substrate increases the friction between the phosphorene and the tip. For bilayer phosphorene, its friction highly depends on its stacking mode, which determines the contact interface with a commensurate or incommensurate pattern. This friction behavior is quite unique and greatly differs from that of graphene and molybdenum disulfide. Detailed analysis reveals that this behavior results from the combination effect of the friction contact area, the potential-energy profile of phosphorene, and its unique elongation.

Molecular Dynamics Study on the Tribological Properties of Phosphorene/Polyethylene Composites

“…Moreover, Bai et al evaluated the potential energy map of PS by scanning its surface in the x-y plane. The potential-profile period of the PS was consistent with its lattice periodicity, leading to the high friction behavior anisotropy of composites [17]. However, the interfacial energy slightly increased as the number of PS layers increased, whereas the friction force still decreased as the number of PS layers increased (Figure 7).…”

“…As discussed in previous studies [17], the PS exhibited high friction anisotropy arising from the unique shrinking structure of PS; hence, we the friction anisotropy of composites must be discussed. The effects of the friction angle on the friction force and abrasion rate of composites under 1 PS layer, L = 40 Å and V x = 10 Å/ps is presented in Figure 4.…”

“…Therefore, under a fixed normal load F n , the composites with a greater number of PS layers could restrict the tip from penetrating into the composites, thereby decreasing the contact area. Studies have reported that the interfacial adhesion strength is strongly influenced by the contact area [17]. When relative motion occurs between asperities, the temperature in the contact area rapidly increases.…”

“…To explore this relationship, Li et al investigated the enhancement of the tribological properties of polymer composites reinforced by functionalized graphene [39]. They revealed that the enhancement of functionalized graphene was stronger than that of pristine graphene because the functionalization process improved the adhesion Studies have reported that the interfacial adhesion strength is strongly influenced by the contact area [17]. When relative motion occurs between asperities, the temperature in the contact area rapidly increases.…”

“…Compared to other 2D materials, PS has attractive properties, such as high charge-carrier mobility, in-plane anisotropy, and adjustable bandgap depending on the number of layers [14][15][16]. These properties, especially the significant anisotropy along different directions, enable PS/polymer composites to have a broader range of potential applications as reinforcement materials than other 2D materials [17,18]. Moreover, most 2D materials can be added to polymers to enhance their tribological and mechanical behaviors.…”