Onion-shell nuclei on monolayer MoS2 facilitate friction reduction
Haowen Luo,
Shenghong Liu,
Zhihuan Li,
Yuan Li,
Alain Dubois,
Yadong Xu,
Nan Kang,
Mohamed El Mansori,
Feng Zhou,
Jianxi Liu
Affiliations
Haowen Luo
State Key Laboratory of Solidification Processing, Center of Advanced Lubrication and Seal Materials, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China
Shenghong Liu
State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
Zhihuan Li
State Key Laboratory of Solidification Processing, Center of Advanced Lubrication and Seal Materials, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China
Yuan Li
State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
Alain Dubois
Laboratory of Physical Chemistry – Matter and Radiation, Sorbonne Université, CNRS, Paris 75005, France
Yadong Xu
State Key Laboratory of Solidification Processing, Center of Advanced Lubrication and Seal Materials, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China
Nan Kang
Arts et Metiers Institute of Technology, MSMP, HESAM Université, Châlons-en-Champagne F-51006, France
Mohamed El Mansori
Arts et Metiers Institute of Technology, MSMP, HESAM Université, Châlons-en-Champagne F-51006, France
Feng Zhou
State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
Jianxi Liu
State Key Laboratory of Solidification Processing, Center of Advanced Lubrication and Seal Materials, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China
Monolayer MoS2 has garnered significant interest because of its exceptional optoelectronic and tribological properties and potential application as a lubrication layer in micro- and nanoelectromechanical systems. Although the nanotribological performance of chemical vapor deposition (CVD)-grown MoS2 and the characteristics associated with CVD growth have been extensively studied, challenges remain in designing specific regions on the monolayer MoS2 surface with reduced friction. Here, we develop nuclei with an onion-shell structure on CVD-grown monolayer MoS2 to achieve remarkable friction and adhesion reduction. These nuclei, dispersed on high-quality and crystalline MoS2, consist of an oxi-sulfide core surrounded by a multilayer MoS2 shell. Lateral force microscopy results indicate that onion-shell nuclei create an ensemble effect that decreases friction and adhesion by up to 45% and 20%, respectively, compared with those of MoS2 because of the multilayer structure and in-plane tensile strain, both of which minimize out-of-plane deformation. Derjaguin–Müller–Toporov (DMT) model calculations and step-down load‒friction correlations illustrate that the work of adhesion, shear strength, and coefficient of friction on the nucleus decrease by more than 22%, 19%, and 34%, respectively, compared with those on MoS2. The onion-shell nucleus presents a novel lubrication strategy to mitigate friction and adhesion in CVD-grown two-dimensional (2D) materials, with potential applications in lubricating nanoscale friction pairs.
