1. Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian, China 116024
2. School of Physics, Dalian University of Technology, Dalian, China 116024
3. Marine Engineering College, Dalian Maritime University, Dalian, Liaoning, China 116026
4. Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, China 100083
5. School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States