[1] Peking Univ, Dept Adv Mat & Nanotechnol, Coll Engn, Beijing 100871, Peoples R China
[2] Peking Univ, Beijing Natl Lab Mol Sci, State Key Lab Rare Earth Mat Chem & Applicat, Coll Chem & Mol Engn, Beijing 100871, Peoples R China
[3] Brown Univ, Dept Chem, Providence, RI 02912 USA