1. Department of Electrical Engineering; The State University of New York at Buffalo; Buffalo NY 14260 USA
2. Department of Materials Science; Fudan University; Shanghai 200433 China
3. Department of Environmental Science and Engineering; Fudan University; Shanghai 200433 China
4. Department of Chemistry; The State University of New York at Buffalo; Buffalo NY 14260 USA
5. Department of Electrical and Computer Engineering; University of Wisconsin; Madison WI 53705 USA