Zhi Yang1, Yaokun Pang1, Limin Zhang1, Cunxin Lu1, Jian Chen1, Tao Zhou1, Chi Zhang1, Zhong Lin Wang1,2
1Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy
of Sciences, and National Center for Nanoscience and Technology (NCNST), Beijing 100083, P. R. China
2School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States