[1] Northeast Agr Univ, Coll Engn, Harbin 150030, Heilongjiang, Peoples R China
[2] Chinese Acad Sci, Beijing Inst Nanoenergy & Nanosyst, Beijing 101400, Peoples R China
[3] Univ Chinese Acad Sci, Sch Nanosci & Technol, Beijing 100049, Peoples R China
[4] Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA