title: Soluble, Exfoliated Two-Dimensional Nanosheets as Excellent Aqueous Lubricants.
abstract: Dispersion in water of two-dimensional (2D) nanosheets is conducive to their practical applications in fundamental science communities due to their abundance, low cost, and ecofriendliness. However, it is difficult to achieve stable aqueous 2D material suspensions because of the intrinsic hydrophobic properties of the layered materials. Here, we report an effective and economic way of producing various 2D nanosheets (h-BN, MoS2, MoSe2, WS2, and graphene) as aqueous dispersions using carbon quantum dots (CQDs) as exfoliation agents and stabilizers. The dispersion was prepared through a liquid phase exfoliation. The as-synthesized stable 2D nanosheets based dispersions were characterized by UV-vis, HRTEM, AFM, Raman, XPS, and XRD. The solutions based on CQD decorated 2D nanosheets were utilized as aqueous lubricants, which realized a friction coefficient as low as 0.02 and even achieved a superlubricity under certain working conditions. The excellent lubricating properties were attributed to the synergetic effects of the 2D nanosheets and CQDs, such as good dispersion stability and easy-sliding interlayer structure. This work thus proposes a novel strategy for the design and preparation of high-performance water based green lubricants.
authors.affiliation: College of Materials Science and Engineering, Laboratory of Fiber Materials and Modern Textile, The Growing Base for State Key Laboratory, Qingdao University , Qingdao 266071, China.
authors.forename: Wenling
authors.initials: W
authors.lastname: Zhang
authors.affiliation: College of Materials Science and Engineering, Laboratory of Fiber Materials and Modern Textile, The Growing Base for State Key Laboratory, Qingdao University , Qingdao 266071, China.
authors.forename: Yanlin
authors.initials: Y
authors.lastname: Cao
authors.affiliation: State Key Laboratory of Tribology, Tsinghua University , Beijing 100084, China.
authors.forename: Pengyi
authors.initials: P
authors.lastname: Tian
authors.affiliation: State Key Laboratory of Tribology, Tsinghua University , Beijing 100084, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Tribology, Tsinghua University , Beijing 100084, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Tian
authors.affiliation: College of Materials Science and Engineering, Laboratory of Fiber Materials and Modern Textile, The Growing Base for State Key Laboratory, Qingdao University , Qingdao 266071, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Zheng
authors.affiliation: College of Materials Science and Engineering, Laboratory of Fiber Materials and Modern Textile, The Growing Base for State Key Laboratory, Qingdao University , Qingdao 266071, China.
authors.forename: Xuqiang
authors.initials: X
authors.lastname: Ji
authors.affiliation: College of Materials Science and Engineering, Laboratory of Fiber Materials and Modern Textile, The Growing Base for State Key Laboratory, Qingdao University , Qingdao 266071, China.
authors.forename: Jingquan
authors.initials: J
authors.lastname: Liu
keywords: 2D nanosheets; carbon quantum dots; dispersion stability; friction coefficient; synergistic effect