Ze Yang1,2,†, Yiyong Yang2,†, Hao Wang1, Fan Liu1,3, Yijia Lu1, Linhong Ji1,* Zhong Lin Wang4,5,* and Jia Cheng1,*
1 State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing, 100084 P. R. China
2 School of Engineering and Technology, China University of Geosciences (Beijing), Beijing, 100083 P. R. China
3 Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139 USA
4 Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, 100083 P. R. China
5 School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA, 30332 USA
† Z.Y. and Y.Y. contributed equally to this work.