1. School of Physics and ElectronicsState Key Laboratory of Advanced Design and Manufacturing for Vehicle BodyHunan Provincial Key Laboratory of Multi‐Electron Based Energy Storage DevicesHunan University Changsha 410082 P. R. China
2. Physics and Electronic Engineering DepartmentXinxiang University Xinxiang 453003 P. R. China
3. College of Chemistry and Chemical EngineeringCentral South University Changsha 410083 P. R. China
4. Fujian Strait Research Institute of Industrial Graphene Technologies Quanzhou 362000 P. R. China