1. Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, Key Laboratory of Cluster Science, Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, P. R. China
2. Research Institute of Petroleum Exploration and Development, China National Petroleum Corporation, No. 20 Xueyuan Road, Haidian District, Beijing 100083, P. R. China
3. Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China