[1] Natl Univ Singapore, Dept Chem, 3 Sci Dr 3, Singapore 117543, Singapore
[2] Peking Univ, Ctr Res Excellence & Technol Enterprise CREATE, Res Ctr, Singapore 138602, Singapore
[3] Natl Univ Singapore, Dept Phys, Singapore 117551, Singapore
[4] Peking Univ, Coll Chem & Mol Engn, BNLMS, SKLSCUSS, Beijing 100871, Peoples R China
[5] Natl Univ Singapore Suzhou, Res Inst, Suzhou 215123, Jiangsu, Peoples R China