1. Department of Mechanical Engineering, University of California at Berkeley, Berkeley, California 94720, United States
2. Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
3. Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
4. Department of Chemistry and Biochemistry, University of California at Santa Cruz, Santa Cruz, California 95064, United States
5. Department of Physics, Tamkang University, Tamsui, Taiwan 250, Republic of China
6. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
7. Sandia National Laboratories, Livermore, California 94551, United States
8. International Center for Materials NanoArchitectonics, National Institute for Materials Science, Tsukuba 305-0044, Japan