a
Key Laboratory of Rare Earth Chemistry and Physics, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, China
E-mail: lulehui87@yahoo.com.cn
;
Fax: +86-431-5685653
b
State Key Lab. for Physical Chemistry of Solid Surface Department of Chemistry, Xiamen University, Xiamen, China
c
ECE Department, University of Texas at Austin, Austin, USA