1. Department of Energy Conversion and Storage Technical University of Denmark (DTU) Fysikvej, 310 Kgs. Lyngby 2800 Denmark
2. Hubei Province Key Laboratory of Systems Science in Metallurgical Process Faculty of Science Wuhan University of Science and Technology Wuhan 430081 P. R. China
3. Department of Physics Centre for Nanostructured Graphene (CNG) Technical University of Denmark (DTU) Fysikvej, 309 Kgs. Lyngby 2800 Denmark
4. DTU Nanolab Technical University of Denmark (DTU) Fysikvej, 307 Kgs. Lyngby 2800 Denmark