[1] Xi An Jiao Tong Univ, Sch Chem, Xian 710049, Peoples R China
[2] Xi An Jiao Tong Univ, State Key Lab Elect Insulat & Power Equipments, Xian 710049, Peoples R China
[3] Xi An Jiao Tong Univ, MOE Key Lab Nonequilibrium Synth & Modulat Condens, Xian 710049, Peoples R China
[4] North Carolina Agr & Tech State Univ, Joint Sch Nanosci & Nanoengn, Greensboro, NC 27401 USA