1. Jiangxi Copper Technology Institute Co., Ltd., Nanchang 330096, P. R. China
2. Division of Nanomaterials and Jiangxi Key Lab of Carbonene Materials, Jiangxi Institute of Nanotechnology, Nanchang 330200, P. R. China
3. Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, P. R. China