1. Key Laboratory of Hubei Province for Coal Conversion and New Carbon Materials School of Chemistry and Chemical Engineering Wuhan University of Science and Technology 947 Heping Avenue Qingshan District Wuhan 430081 Hubei Province P. R. China
2. Key Laboratory of Hubei Province for Plasma Chemistry and Advanced Materials School of Materials Science and Engineering Wuhan Institute of Technology 206 Donghu New Technology Development Zone Road Wuhan 430073 Hubei Province P. R. China
3. School of Materials and Energy University of Electronic Science and Technology of China 2006 Xiyuan Avenue High-tech zone (West district) Chengdu 611731 Sichuan Province P. R. China
4. School of Materials Science and Engineering National University of Singapore 21 Lower Kent Ridge Road Singapore 117579 Singapore