1. State Key Laboratory of Chem/Bio-Sensing and Chemometrics Provincial Hunan Key Laboratory for Graphene Materials and Devices College of Chemistry and Chemical Engineering The National Supercomputer Centers in Changsha Hunan University Changsha 410082 P. R. China
2. College of Chemistry and Chemical Engineering Shaanxi Collaborative Innovation Center of Clean Utilization of Low Rank Coal Yan'an University Yan'an Shaanxi 716000 P. R. China