1. College of Chemistry and Pharmaceutical Sciences, Qingdao Agricultural University, Qingdao, Shandong, P. R. China
2. Shandong Laboratory of Advanced Materials and Green Manufacturing at Yantai, Yantai, Shandong, P. R. China
3. State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, P. R. China
4. Qingdao Key Laboratory of Lubrication Technology for Advanced Equipment, Qingdao Center of Resource Chemistry & New Materials, Qingdao, P. R. China