[1] Chinese Acad Sci, Lanzhou Inst Chem Phys, State Key Lab Solid Lubricat, Lanzhou 730000, Peoples R China
[2] Univ Chinese Acad Sci, Beijing 100049, Peoples R China
[3] Lanzhou Univ, Sch Phys Sci & Technol, Inst Nanosci & Nanotechnol, Lanzhou 730000, Peoples R China