Protein-induced ultrathin molybdenum disulfide (MoS₂) flakes for a water-based lubricating system

Abstract

Monolayer or ultrathin transition metal dichalcogenides cover a wide range of atomically thin twodimensional (2D) materials, whose fascinating properties have made them promising candidates for many applications. In this work, ultrathin MoS 2 flakes were successfully exfoliated, induced by bovine serum albumin (BSA) or hemoglobin (HB), under vigorous ultra-sonication. They were used as additives for water-based lubricating systems and related investigations indicated that they could improve the friction performance and anti-wear abilities at a relatively low concentration: 0.10 wt% of additive contents can make the average friction coefficient stabilize in the range between 0.06 and 0.08, which results from the formation of a dynamic protective film on the friction surfaces. The protein-induced ultrathin MoS 2 flakes are also expected to be useful for other hydrophilic lubrication systems, which possess great scientific value and promising application prospects compared with bulk or microscale lubricating additives.

Functionalized Hybridization of 2D Nanomaterials

“…[98] As reported, the WSe 2 -BSA nanosheets were employed as efficient photothermal moieties and photosensitizing agent carrier for photodynamic therapy (Figure 7). [101] Besides BSA, other proteins such as Adv. [100] Additionally, MoS 2 -BSA sheets were also used as promising lubricating additive to improve friction-reducing and anti-wearing performance at a relatively low concentration.…”

Composites of Proteins and 2D Nanomaterials

“…However, unlike graphene‐based nanomaterials, TMDC sheets do not commonly utilize hydrogen bonding . Moreover, pristine TMDC nanosheets do not possess hydrophilic functional groups like graphene derivatives, which can form hydrogen bonds with proteins, but, it is possible to generate these hydrophilic groups by introducing edge defects to the TMDC sheets . Similar to graphene, hydrophobic interactions occur between the hexagonal lattice of TMDCs and the hydrophobic/aromatic functional groups of specific amino acids (alanine, valine, isoleucine, leucine, methionine, phenylalanine, tyrosine tryptophan) ( Figure a) .…”

“…Protein based exfoliation of TMDCs are frequently performed using BSA, which can facilitate both hydrophobic interactions through amino acids with aromatic side chains, and disulfide bonds (e.g., with MoS 2 ) through amino acids of phenylalanine and cysteine, respectively . The exfoliated sheets of MoS 2 with BSA molecules attached to their surface were used in lubrication systems, and tumor therapy as photothermal drug release agents .…”

Controllable synthesis of different morphologies of CuO nanostructures for tribological evaluation as water-based lubricant additives

“…Many nanomaterials are beneficial for improving tribological properties of water-based lubricants [6][7][8]. Graphene and graphene oxide [9][10][11], carbon dots [12], hard carbon spheres [13], carbon nanotubes [14], ionic liquids [15], sulfides [16][17][18], oxides [2,7,19], and metal nanocopper [20,21] have been designed and synthesized to improve the performance of water. Furthermore, a number of lubrication mechanisms have been proposed to explain the improvement of tribological performance, including: (a) formation of physical or/and chemical tribofilms.…”